Introduction of Mandatory Meps For Distribution Transformers in Australia

Chapter Six: Introduction of Mandatory MEPS for Distribution Transformers in Australia
6. INTRODUCTION OF MANDATORY MEPS FOR DISTRIBUTION

TRANSFORMERS IN AUSTRALIA
6.1. Background
6.1.1. Regulatory Framework for MEPS
Energy consumed by various equipment and appliances is a major source of greenhouse
emissions. The most effective (and widely used) measure to reduce greenhouse emissions
attributable to equipment and appliances is application of Codes and performance
standards. Under the 1998 National Greenhouse Strategy, responsibility for the Australian
Appliance and Equipment Energy Efficiency Program resides with Australian and New
Zealand Minerals and Energy Council (ANZMEC). ANZMEC comprises the Minister of
State from each Australian jurisdiction and New Zealand responsible for energy matters.
This program provides “an important stimulus for the development of world-class energy
efficient products. Benefits can flow through to the general community in the form of
monetary savings from lower operating costs and increased employment levels resulting
from Australian industry’s ability to exploit potential export markets”, (NAEEP, 2001a).
Minimum Energy Performance Standards (MEPS) is a government regulatory program
included in the state and territory laws that excludes from the market products, which do
not meet the minimum energy performance levels. The National Appliance and
Equipment Energy Efficiency Committee (NAEEEC) is a regulatory body that includes
energy efficiency officials and regulators that implement the MEPS program and range of
supporting measures in Australia and New Zealand. This body is also responsible for
provision of relevant information for consideration by the ANZMEC. ANZMEC has
A New Approach to Assessment and Utilisation of Distribution Power Transformers – S. Corhodzic PhD Thesis 93
authorised NAEEEC to develop and publish plans for MEPS for any industrial or
commercial equipment identified as a significant contributor to the growth in energy
demand or greenhouse gas emissions. These plans represent “a transparent way for
government agencies to explore community and stakeholder support (for both mandatory
and voluntary measures) to reduce greenhouse gas emissions produced by these types of
equipment” (NAEEP, 2001a). The MEPS development process includes feasibility
assessment (technical, economic cost-benefit analyses and available supervisory measures)
and wide public consultations before any final decision is made.
6.1.2. Why Are Distribution Transformers Being Considered For MEPS
Distribution Transformers are being considered for MEPS due to the following:
• there is a large number of distribution transformers and due to the fact that
almost all power generated in Australia passes through distribution transformers
means even small improvements in transformer efficiency can result in
significant savings of energy and in greenhouse gases reduction;
• electricity distribution transformers have a very long life (estimates range from
average of 25 years to as much as 50 years for lightly loaded distribution
transformers);
• the cost of transmission and distribution losses are passed on to consumers and
the electricity utilities who are responsible for purchasing most of the
transformers are not motivated to invest in more efficient distribution
transformers;
• there is no market incentive for private purchasers of distribution transformers
(around 15% of the market) to purchase efficient distribution transformers as
they easily include increased energy cost of inefficient distribution transformers
into their total operating expenses (these costs are included into final cost of
their products and services);
• “cumulative savings by 2015 resulting from the introduction of MEPS in 2005
are estimated to be at least 346,000 tons of carbon dioxide equivalent (CO2-e)
and could be as high as 950,000 tons CO2-e” NAEEP (2001a).
6.1.3. The Original MEPS Program
In 1994 NAEEEC commenced investigations about potential benefits of mandating
MEPS for distribution transformers. In 2000 a Steering Group including representatives
from the industry and the Government was established with aims to advance the
investigations.
The original program proposed to regulate liquid type distribution transformers with
power ratings from 10 - 2,500 kVA and an input voltage of more than 5 kV and dry type
transformers from 15 - 2,500 kVA. The NAEEEC developed a multi-staged public
consultation process aiming to introduce nationally consistent standards for distribution
transformers around July 2003. The aim was to increase the energy efficiency of
distribution transformers by:
• mandating MEPS within relevant state and territory legislation commencing in July
2003 that match the relevant Canadian standards for distribution transformers
(CAN/CSA-C802.1 and CAN/CSA-C802.2, 2001);
• exploring stakeholder support for developing higher energy performance standards
for products to be marketed as “high efficiency” distribution transformers,
possibly at a level that matches US standards for distribution transformers, which
were to come into force by July 2003;
• helping stakeholders to promote high efficiency products to the Australian
marketplace.
6.2. Development of MEPS Methodology for Australian Distribution

Transformers.
Development of MEPS for distribution transformers requires appropriate test procedures
for measuring energy consumption as well as data on the efficiency and other relevant
market intelligence. GWA (2002) provided a brief analysis of two main approaches to
develop MEPS methodology and to establish appropriate MEPS levels:
• the statistical approach;
• the engineering approach.
The statistical approach is focused on a specific market at a specific time. It includes
setting a standard efficiency levels based on available statistical energy efficiency data and
energy costs. “The results of such an analysis are both time dependent and country-
dependent, and reflect the particular costs and energy efficiency characteristics of the range
of models available at a specific time in a particular market” GWA (2002).
The engineering analysis approach involves selection of a representative model. Such a
“baseline” model normally incorporates the characteristics and technological features
typical of a group of products under investigation. Alternative design options and
combinations of options are then assessed, using the “baseline” model as a starting point.
A variation of this approach is used in this research, as this method has a number of
advantages over the statistical approach and its variants GWA (2002):
• “it explicitly analyses the relationships between energy consumption, product price
and capacity or level of energy service, and so allows estimates to be made on the
effects of changing those relationships. In the statistical approach the existing
relationships are considered to hold;
• there is no need to consider the number of existing models which meet the criteria
found to be most cost-effective. This is not important provided the industry has a
capacity to produce complying models within a specified time, without
unacceptable adjustment costs (which are separately analysed);
• the approach is less sensitive to time and place, since it concentrates on product
design and manufacture rather than market structure. However, it is still market
dependent to the extent that the “baseline” models selected for analysis are typical
of the market in question”.
It should be noted, however, that this engineering method is time-consuming, resource-
intensive and data-intensive and requires access to proprietary design information from
manufacturers and/or detailed knowledge of design and manufacturing principles).
Development of Australian MEPS levels for distribution transformers is based on global
Australian strategy for development of MEPS, which is endorsed by ANZMEC in 1999.
This strategy relies heavily on MEPS methodologies developed in other markets (based on
engineering and/or statistical approaches). This strategy is outlined in “National Appliance
and Equipment Energy Efficiency Program: Future Directions 2002-04” NAEEEP
(2001):
“In 1999 ANZMEC agreed that Australia would match the best MEPS levels of our
trading partners after taking account of test method differences and other differences (eg
climate, marketing and consumer preference variations). This new policy represented a
radical change of direction from the previous Australian practice of debating the technical
possibilities of MEPS levels with all stakeholders. The new policy covered any product
regulated by mandatory labelling or MEPS programs in other developed countries.”
In summary, this strategy defines the following steps in considering new MEPS, or
revisions to existing MEPS, for any given product GWA (2002):
• “establish what MEPS levels, if any, apply in the countries with which there is
significant Australian trade;
• take account of test method differences and other differences (eg climate,
marketing and consumer preference variations), and adjust MEPS levels
accordingly;
• subject the adjusted MEPS levels to cost-benefit, greenhouse reduction and other
appropriate analyses (working with key stakeholder representatives);
• formally consult with stakeholders;
• if the adjusted MEPS levels pass the appropriate tests, adopt them”.
It should be noted, however, that ANZMEC approach does not limit application of
MEPS only to products, which were assessed in the other markets and it does not exclude
application of cost-effectiveness criteria GWA (2002).
6.3. Regulatory Impact Statement GWA (2002)
The Council of Australian Governments (COAG) requires that the proposal such as
MEPS for distribution transformers must be subject to a Regulatory Impact Statement
(RIS). The RIS estimates the benefits, costs and other impacts of the proposal. It also
assesses the likelihood of the proposal meeting its major objectives: “The purpose of
preparing a Regulatory Impact Statement is to draw conclusions on whether regulation is
necessary, and if so, on what would be the most efficient regulatory approach. Completion
of a RIS should ensure that new or amended regulatory proposals are subject to proper
analysis and scrutiny as to their necessity, efficiency and net impact on community welfare.
Governments should then be able to make well-based decisions. The process emphasises
the importance of identifying the effects on groups who will be affected by changes in the
regulatory environment, and consideration of alternatives to the proposed regulation.
Impact assessment is a two step process: first, identifying the need for regulation; and
second, quantifying the potential benefits and costs of different methods of regulation. In
demonstrating the need for the regulation, the RIS should show that an economic or social
problem exists, define an objective for regulatory intervention, and show that alternative
mechanisms for achieving the stated objective are not practicable or more efficient”
COAG (1997).
The RIS for MEPS for distribution transformers GWA (2002) has considered the
following options:
• “status quo - business as usual (BAU);
• the proposed regulation (mandatory MEPS) which adopts all the requirements
contained in Draft Australia Standard 2374;
• an alternative regulation which only adopts those parts of the Standard that are
essential to satisfy regulatory energy objectives (targeted regulatory MEPS);
• voluntary MEPS, where minimum energy efficiency levels for distribution
transformers would be made publicly available, and industry is encouraged, but not
compelled to adhere to the proposed levels;
• another regulatory option involving a levy imposed upon inefficient equipment to
fund programs to redress the greenhouse impact of equipment energy use;
• a levy on electricity reflecting the impact it has on greenhouse gas emissions”
GWA (2002).
6.3.1. Estimated Greenhouse Gas Reductions
According to GWA (2000): “Distribution transformers in the Australian electricity
system account for around 25% of transmission and distribution losses, equivalent to
5,450 GWh or approximately 5,400,000 tons CO2-e (based on data for 1998). Electricity
consumption is predicted to grow steadily and distribution losses may slightly increase as
a result of the change to lower nominal voltage of 230 V as proposed by AS 60038–
2000. These factors are likely to outweigh the estimated decrease in the greenhouse
intensity of electricity, so that by 2015 losses due to distribution transformers are
estimated to be at least 6,000,000 tons CO2-e. Discussions with the industry suggest that
the large majority of pre MEPS distribution transformers complied with the proposed
MEPS. The area where most benefits have arisen was the private ownership market
where the least efficient products are typically installed. This tends to be the largest
market for dry-type transformers where lower efficiency levels are found.
Based on available information concerning the stock and performance of Australian
distribution transformers, the proposed MEPS level in 2005 would reduce greenhouse
emissions by approximately 32,000 tons CO2-e per annum, with a successively larger
impact in subsequent years. Cumulative savings from MEPS in the years to 2010 and to
2015 are estimated to be 185,000 tons CO2-e and 346,000 tons CO2-e, respectively. If
the trend continues towards the purchase of lower efficiency transformers in Australia,
greenhouse savings as a result of MEPS in 2015 would be between 650,000 tons CO2-e
to 950,000 tons CO2-e.”
6.3.2. Estimated Economic Implications - Original MEPS Program
“Since Australian manufacturers can supply a wide range of high efficiency transformers,
MEPS should not unjustifiably disadvantage any single supplier. The MEPS itself is not a
trade barrier. There is, however, a capital cost premium for efficiency in transformers
reflecting increased material costs and, in some cases, handling costs. For example,
industry claim that the approximate cost difference between the “low loss” transformers
and the “industrial” range is in the region of 10 - 20%.
Without regulation, the increasing pressure on purchasers to reduce capital costs is likely
to result in a growth of inefficient transformers sold on a “first-cost” basis by importers.
This would have ramifications for Australian manufacturers as well as broader economic
and greenhouse impacts” GWA (2002).
6.3.3. Cost-Benefit Analysis for MEPS Program
The benefits from the MEPS for distribution transformers are calculated as the Net
Present Value (NPV) at 10% discount rate of the projected reduction in electricity losses.
Greenhouse gas emission savings have not been valued.
The cost arising from MEPS for distribution transformers is the NPV of the projected
increase in the price of transformers due to increased efficiency. The RIS states that
introduction of MEPS would not introduce any additional program costs, “since
transformer energy efficiency testing is already common and the administrative
infrastructure for MEPS already exists” GWA (2002).
In addition, the RIS concludes that “the benefit/cost ratios range from 1.0 to 1.2 for
utility-owned transformers, where the value of losses is related to the wholesale price of
energy, and 3.3 to 4.0 for privately owned transformers, which face much higher marginal
electricity prices and for which the value of electricity saved is consequently higher. The
projections represent a price/efficiency ratio of 0.5. For private transformers, MEPS
remain cost effective up to ratios of 1.8”, GWA (2002).
6.3.4. Other RIS Considerations GWA (2002)
The RIS also considered the following issues:
• supplier and trade issues - distribution transformers are manufactured and freely
traded in all developed countries in the Asia Pacific region. Introduction of MEPS
levels is not likely to significantly change the number of suppliers, nor the price
competition between them;
• market failure - introduction of mandatory “MEPS option would address market
failure in the private transformer market, and the increasing risk of market failure
in the utility transformer market, by enforcing investment in more efficient
products so that the total life cycle cost of transformers to users would be lower
than otherwise”;
• information failure - “mandatory MEPS option would be to introduce consistency
in declarations of transformer energy efficiency and in the designation of “high
efficiency” models. The introduction of MEPS would put reliable data on the
energy efficiency of every transformer model in the public domain for the first
time;
• product quality - MEPS are not expected to have any negative effect on product
quality or function. Actually, increase in transformer efficiency “should lead to
lower heat gain in operation, and hence lower failure rates and higher overall
network reliability”;
• world’s best practice - “Canada and Mexico have MEPS for transformers, and the
European Union and the USA are considering implementing them. The proposed
MEPS levels are based on and equivalent to, the most stringent currently in place
(those for Canada, which took effect in January 2002) and so are consistent with
the principle adopted by ANZMEC - matching but not exceeding the most
stringent MEPS levels in force elsewhere. The proposed criteria for designating
transformers as “high efficiency” are roughly equivalent to the MEPS levels under
consideration for the EU and the USA, and as such are an indicator of the likely
direction of world’s best practice”.
6.4. Proposed MEPS Levels for Distribution Transformers
6.4.1. Summary of MEPS for Distribution Transformers
From 1 October 2004, most distribution transformers rated between 10 and 2,500 kVA
that are designed for 11 and 22 kV networks are required to meet minimum energy
performance standards (MEPS) in order to be sold in Australia. Mandatory energy
performance levels are contained in the Australian Standard AS2374.1.2:2003 Power
Transformers - Minimum Energy Performance Standard (MEPS) Requirements For
Distribution Transformers, and apply to single and three phase, dry type and oil immersed
transformers. After 1 October 2004, distribution transformers that meet more stringent
performance levels than MEPS (also specified in AS2374.1.2) are allowed to be promoted
as “High Efficiency Power Transformers”. Appendix 2 provides more details about the
Australian Standard AS2374.1.2 and lists special distribution transformers, which are not
subject to MEPS. The values for MEPS are given in Appendix 3. These MEPS are
expressed as efficiency levels at 50% of nominal load. The test methods which should be
used to determine compliance with MEPS for distribution transformers are defined in
AS2374.1-1997 Power Transformers and AS2735-1984 Dry Type Power Transformers.
Distribution transformers, as regulated products, offered for sale after 1 October 2004
must be registered with a State regulator. The distribution transformers, which were
registered with Australian Greenhouse Office (Energy Efficiency) by January 2005, are
presented in Appendix 1.
The Australian program and regulation for energy efficiency in distribution transformers is
being followed by New Zealand regulators.
6.4.2. Summary of RIS Conclusions
The RIS concluded that the mandatory MEPS option is “likely to be effective in meeting
its stated objectives:
• the mandatory MEPS option can deliver a better rate of improvement for energy
efficiency of transformers in Australia than market forces. MEPS can
demonstrably improve the energy efficiency of appliances and equipment,
particularly where the purchaser is able to pass on inefficient running costs to
third parties;
• none of the alternatives examined appear as effective in meeting all objectives,
some would be completely ineffective with regard to some of the objectives, and
some options appear to be far more difficult or costly to implement;
• the projected monetary benefits of the mandatory MEPS option appear to exceed
the projected costs by a ratio of about 1.4 to 1, without assigning monetary value
to the reductions in CO2 emissions that are likely to occur (possibly as high as
870,000 tones CO2-e per annum by 2010);
• the benefit/cost ratio for privately-owned transformers is significantly higher than
for utility-owned transformers”.
6.5. Comparison of Australian and US cost benefit approaches to MEPS
McMahon (2004) compared US and Australian approaches to analysis of costs and
benefits of minimum energy performance standards (MEPS). In his report, prepared for
the Australian Greenhouse Office and the Collaborative Labelling and Appliance
Standards Program (CLASP), McMahon analysed some other appliances in the presented
case studies, however, the findings are also relevant for distribution transformers MEPS.
The report also suggests improvements for the approach taken in Australia
The MEPS in Australia and USA are subject to distinctive and specific constraints as the
overall purposes of the programs are different:
• the purpose of the Australian program is to reduce greenhouse gas emissions;
• the purpose of the US program is to increase energy efficiency.
The market structures are different:
• Australia imports significantly large share of its distribution transformers
(especially dry-types);
• most of the USA distribution transformers are produced locally.
The policy contexts are again different:
• Australia adopts the MEPS already in place elsewhere (i.e. Canadian Standards for
distribution transformers);
• the US regulatory bodies are “conducting pioneering engineering-economic studies
to identify maximum energy efficiency levels that are technologically feasible and
economically justified”.
The approaches to determining the relationship of price to energy efficiency also differ:
• the Australian approach is based on the current market data;
• the US approach uses prospective estimates.
The report recommends that both approaches be refined by including “retrospective
analysis of impacts of MEPS on appliance and equipment prices”.
The capitalisation of losses (Total Operating Costs and Life-Cycle Cost) methods are
similar (more details about these two methods are given in Chapter 5):
• Australia uses average values, and this method could be improved if more data
were available.
• the US approach uses statistical surveys that permit a more detailed analysis, based
on full distributions (rather than average values).
The methods for the national cost - benefits analyses methods are very similar, however
the methods would benefit by introduction of additional sensitivity analyses.
In addition, consideration should be given to lower discount rates, which “could lead to
more stringent MEPS in some cases”.
The technology and market assessments are similar and no changes are recommended for
either approach.
Both the Australian and the US analyses impacts on industry, competition, and trade are
quite detailed and the report does not recommend any changes.
In conclusion, “Australia’s analysis approach could be expected to have less analytical
detail and still result in MEPS levels that are appropriate for their policy and market
context. In practice, the analysis required to meet these different objectives is quite similar.
To date, Australia’s cost-benefit analysis has served the goals and philosophies of the
program well and been highly effective in successfully identifying MEPS that are
significantly reducing greenhouse gas emissions while providing economic benefits to
consumers. In some cases, however, the experience of the USA - using more extensive
data sets and more detailed analysis - suggests possible improvements to Australia’s cost-
benefit analysis”.
It seems that recommended changes “would increase the depth of analysis, require
additional data collection and analysis, and incur associated costs and time. The
recommended changes are likely to have incremental rather than dramatic impacts on the
substance and implications of the analysis as currently conducted” McMahon (2004).
6.6. International Energy Efficiency Standards and Programs for Distribution

Transformers
6.6.1. Liberalisation of the Electricity Market
LE (2005) analyses main barriers (and recommends possible remedial measures) for
electrical utilities’ investments into high efficiency equipment in a liberalized electricity
market:
• “most regulatory models rely on a partial redistribution of savings to consumers.
This discourages companies from making investments for efficiency
improvements, since cost reduction from the investment are shared with the
consumers. It would be advisable to allow some carryover of measurable
efficiency gains, so that investing in energy efficiency becomes more attractive for
the network companies;
• capital-intensive investments are very sensitive to future changes in the regulatory
regime. This discourages investments in efficiency improvements. Special
incentives should be given to promote capital-intensive energy efficiency measures
(in a stable regulatory system);
• the regulatory framework tends to concentrate on cost savings in the short term.
Such an approach does not encourage companies to take the life cycle costs of
equipment into account. There should be incentive for network operators to take
LCC into account;
• energy losses are calculated without consideration of external costs. The true cost
of network losses should be taken into account”.
The following summary of efficiency standards and status of MEPS programs and
activities in different countries to address the tendency of both utilities and non-utilities to
purchase distribution transformers of lower efficiency than is cost-effective from a
lifecycle perspective is compiled from Ellis (2001) and LE (2005).
6.6.2. China
The mandatory minimum efficiency standards for power transformers (the “S9” standard)
were introduced in 1999. This standard, approved by the State Bureau of Quality and
Technology Supervision, covers both distribution and power transformers. It limits the
maximum load losses and no-load losses for oil immersed types ranging from 30 to 31,500
kVA as well as for dry types in the range from 30to 10,000 kVA. Introduction of the S9
standard has significantly improved efficiency of power transformers in this market.
6.6.3. Europe
Distribution transformers in the European Union are covered by: world-wide standards
(e.g. ISO, IEC), European standards and regulations (e.g. EN, Harmonization
Documents) and various national standards (e.g. BSI, DIN, UNE, OTEL, etc).
CELEC has defined efficiency standards for three phase distribution transformers in the
range from 50 to 2,500 kVA, 50Hz and up to 36 kV. The standard HD428 defines three
categories for load losses (C, A and B - value of losses in ascending order) and no-load
losses (C’, B’ and A’ - value of losses in ascending order). A similar standard (HD538)
stipulates the load losses and no-load losses of dry type transformers. Distribution
transformers built to HD428 and HD538 have a limited number of preferred values for
rated power (50, 100, 160, 250, 400, 630, 1,000, 1,600 and 2,500 kVA), however, the
intermediate values are also allowed. A separate HD is under consideration for pole-
mounted transformers. Loss values for transformers are usually declared as maximum
values with a specified tolerance. Higher losses may incur a financial compensation for
exceeding the loss limit and the losses lower than the guaranteed may be subject to a
bonus awarded to the manufacturer (this would normally apply for larger transformers).
HD428 therefore allows customers to choose between three levels of no-load losses and
three levels of load losses. In principle, there are 9 possible combinations, ranging from
the lowest efficiency, (BA’) to the highest, (CC’). These efficiency ranges are extremely
wide. The minimum efficiency in the highest category (CC’) is still far below the efficiency
of the best in class and far below the 5-star transformer defined by the Indian standards.
CENELEC is currently defining new efficiency categories with lower losses. In 1999, a
Thermie project of the European Union assessed the total energy losses in distribution
transformers. The savings potential in the 15 countries of the EU was estimated to be 22
TWh. The standards are not as yet mandatory, and a mandatory minimum efficiency
standard for distribution transformers is not expected to be introduced in the near
future. “This is very disappointing, given the availability of world-class transformer
technology in Europe” LE (2005).
6.6.4. Taiwan
“Since 1992, an eco-label program called GreenMark has been run by the Environmental
Protection Administration (EPA) and currently covers over 50 products. For
conforming products, the GreenMark logo label may be used on product packaging,
brochures or on the products themselves. It is intended that distribution transformers
will be covered by this program although the energy performance criteria have not yet
been determined” Ellis (2001).
6.6.5. India
“In India, the Bureau of Energy Efficiency (BEE) has developed a “5-star” classification
scheme for distribution transformers in the range from 25 to 200 kVA. The scheme is a
co-operative venture between public and private organizations that issues rules and
recommendations under the statutory powers vested with it.
The 5-star program stipulates a lower and a higher limit for the total losses in
transformers, at 50% load. The scheme recommends replacing transformers with higher
star rated units. The 5-star unit represents world-class technology, while 3-star is
recommended as a minimum, and already followed by many utilities. India historically
has a rather poor performance in transformer energy efficiency, but this 5-star program
could become an important driver for change” LE (2005).
6.6.6. Japan
“In Japan, transformers are a part of the Toprunner Program, which either defines the
efficiency for various categories of a product type, or uses a formula to calculate
minimum efficiency. This program, which covers 18 different categories of appliances,
has some major differences compared to other Minimum Energy Performance
programs. The minimum standard is not based on the average efficiency level of
products currently available, but on the highest efficiency level achievable. However, the
program does not impose this level immediately, but sets a target date by which this
efficiency level must be reached. A manufacturer’s product range must, on average, meet
the requirement. It is not applied to individual products. Labelling of the products is
mandatory. A green label signifies a product that meets the minimum standard, while
other products receive an orange label” LE (2005).
6.6.7. Mexico
As in Australia, the Mexican standard includes voluntary and mandatory elements. The
Mexican standard, NOM-002-SEDE-1999 defines minimum energy performance
standards and maximum load losses and no-load losses for transformers in the range from
5 to 500 kVA. The standard also defines the compulsory test procedure for determining
efficiency performance. The efficiency levels are less stringent than those proposed for
Canada and the US. The regulation makes allowances for smaller manufacturers, who
may appeal for an exception during transitionary period before meeting the
requirements.
6.6.8. USA
“The energy savings potential in the USA from switching to high efficient transformers
is high. In 1997, the National Laboratory of Oak Ridge estimated it to be 141 TWh.
Utilities purchase over 1 million new units each year, and it is estimated that if the average
efficiency of utility transformers was improved by one-tenth of one percent, greenhouse
emissions reductions of 1,800,000 tones CO2-e per annum would be achieved over a 30
year period. The US has currently has a number of voluntary initiatives designed to
increase the efficiency of distribution transformers USEPA (1998b).
• the National Electrical Manufacturers Association (NEMA) created the TP1
standard - Guide for Determining Energy Efficiency for Distribution
Transformers (TP-1-1996), and a standard test method for the measurement of
energy consumption in transformers (TP-2). The TP1 standard defines a
minimum efficiency for dry and oil-filled type transformers in the range from 10
to 2,500 kVA and it is likely to become the mandatory minimum efficiency level
in the near future;
• secondly, distribution transformers also are part of the broader EnergyStar
labelling program. EnergyStar is a voluntary program that encourages the
participating utilities to calculate the total cost of ownership of their transformers
and to buy the type if it is cost-effective to do. EnergyStar is based on TP1
because EPA was looking to set an easy standard that did not cause protracted
arguments, so it may be tightened in the future;
• the third program in the US, set up by the Consortium for Energy Efficiency
(CEE), aims to increase the awareness of the potential of efficient transformers
in industry. It consists of a campaign to measure the efficiency of industrial
transformers and to stimulate year period. As a result, in the Energy Star
transformer program, participating utilities agree to perform an analysis of total
transformer operating costs, using a standard methodology, and to buy
transformers that meet EnergyStar guidelines when it is cost-effective to do so.
The program provides technical assistance to partners to ensure that
transformers are not oversized, and has developed a Distribution Transformer
Cost Evaluation Model (DTCEM) to provide a standard methodology for the
evaluation of multiple transformer bids. To compliment this tool, the program
also labels transformers, which conform to its targets USEPA (1998a).
The US Department of Energy (DOE) Federal Energy Management Program
encourages government procurement of energy efficient distribution transformers. The
DOE is currently proceeding with industry-wide consultation and the development of
test procedures with a view to the adoption of Minimum Energy Performance
Standards (MEPS) for transformers. No firm implementation commitment has been
made as yet, however test standards under consideration include the ANSI/IEEE
standards (C57.12.90-1993 and C57.12.91-1995) and the NEMA standard (TP-2
1998)” LE (2005) and Ellis (2001).
6.6.9. Canada
“In Canada the Office of Energy Efficiency (OEE) of Natural Resources Canada (NR-
Can) has amended Canada’s Energy Efficiency Regulations (the Regulations) to require
Canadian dealers to comply with minimum energy performance standards for dry-type
transformers imported or shipped across state borders for sale or lease in Canada.
The standards are harmonized with NEMA TP-1 and TP-2 standards. Amendment 6 to
Canada’s Energy Efficiency Regulations was published in 2003. The regulation of dry-
type transformers is included in this amendment with a completion date of January 1,
2005. This requires all dry-type transformers manufactured after this date to meet the
minimum energy performance standards.
As far as oil transformers are concerned Canada has conducted analysis of MEPS
implementation potential and found that the great majority of Canadian oil distribution
transformers already comply with NEMA TP-1 so the standard would almost have no
influence on the market. The yearly MEPS standard impact would only be 0.98 GWh for
liquid filled transformers compared to saving potential at 132 GWh expected for dry-
type transformers. Also EnergyStar products are very actively promoted in Canada” LE
(2005).
6.7. Critical Review of MEPS for Distribution Transformers
It should be highlighted that under the incentive of the National Greenhouse Strategy
(NGS) and due to the strong support from all of the parties involved, the establishment of
the MEPS for Australian distribution transformers passed relatively smoothly. However,
there were some issues of concern which are listed below:
• the MEPS development processes are relatively long and once the performance
levels are established (in a consultative environment) it will be very difficult to
review and change them. Carrying out a new consultation process requires
significant resources. Because of that, minimum efficiency standards are rarely
adjusted to the economics of the market or to new technology developments. This
inflexibility of MEPS regulation should be taken into account through
introduction of much more rigorous assessment methodologies;
• “mandatory Minimum Energy Performance Standards (MEPS) have the advantage
that they achieve immediate effect. Experience from MEPS for other products
shows that from the moment of adopting such standards, the efficiency of the
average new products increases. MEPS success has also been proven
internationally, with China as the most striking example. However, minimum
standards will in most cases be set as a compromise between the requirements of
all parties involved. As a consequence, standards are normally not set high enough
to achieve the full economic and environmental benefits” LE ( 2005).
• although the Regulatory Impact Statement (RIS) prepared by GWA (2002)
concluded that introduction of MEPS does not favour any particular supplier, it
should be noted that this is true only in a short time-frame. New entrants into the
market will have better opportunities to invest into improved high efficiency
designs (e.g. investment into better technology, more attractive long term contracts
with suppliers of high quality components, etc.). If the MEPS levels were raised in
near future it may be more difficult to comply with such higher standard, as this
would require substantial redesign and as a consequence greater capital cost and
there would need to apply a more strict cost benefit analysis than has been done to
date EEA (2003).
• there have been some arguments EEA (2003) that “singling out of one small part
of a network’s total asset base for an alternative regulatory energy performance
standard seems inconsistent and of very limited value given the level of savings
that could be achieved”. According to EEA (2003) the electrical utilities take into
account all equipment performance efficiencies as part of their long-term
investment considerations. Consequently, the need for the implementation of
MEPS needs to be clearly fitted into an electricity regulatory framework, rather
than being solely driven by concerns over reduction of greenhouse gasses. EEA’s
refusal to adopt such an implementation of MEPS was due to their concerns about
apparent “piecemeal coverage of electricity industry assets outside of the
economic / performance regulatory structure”;
• discussions with some of key utilities in New Zealand indicate that the industry
already has higher efficiency levels for distribution transformers (through voluntary
self-regulation) than those proposed by the MEPS and to mandate a lesser
standard than what is being used would be a retrograde step;
• the reports used as a basis for development of MEPS for distribution transformers
in Australia do not discuss rigorously data about the efficiency of the pre-MEPS
models. It seems that for a large part of distribution transformer population the
improvement in efficiency is measured in points of a percent. As the whole
concept is based on 50% loading (and not the actual load, which the distribution
transformer will experience), it is suggested that “a substantial expansion of this
work would be required to rigorously demonstrate that the MEPS standard would
be appropriate” EEA (2003);
• the MEPS alternatives (presented in GWA (2002) and LE (2005)) include labelling
and voluntary schemes. “Labelling is an effective way of bringing transparency to
the market. A clear definition of efficiency, a transparent measurement procedure
and a labelling system should be the start of every mandatory or voluntary
program to increase transformer efficiency. Voluntary schemes do not have the
disadvantages of a mandatory minimum standard. The targets can often be set at a
more ambitious level and reviewing them is less difficult and time consuming.
Consequently, it is a much more flexible system. The main difficulty to overcome
in voluntary programs is reaching a reasonable degree of participation often taking
few years. The goal of a voluntary program should be to make the incentives and
the image so important that it becomes difficult for companies to ignore. High
image value, a meaningful brand presence, and a strong policy context for instance
make the Japanese Toprunner program a good example of an effective scheme”, LE
(2005);
• it seems that the Australian market is generally comfortable with MEPS levels,
however, there were strong views (expressed during the consultation process) that
the method of calculating Australian MEPS was somewhat deficient. In particular,
strong reliance on Canadian MEPS and simple increase of Canadian MEPS to take
account of the different system frequency between North America (60 Hz) and
Australia (50 Hz) was too simplistic. In addition, it is not clear if the applied
methodology considered difference in definition of kVA rating between the two
standards. As the North American and Australian electrical distribution systems
are quite different (e.g. predominantly single phase supply and a large number of
smaller less efficient distribution transformers in North America versus mostly
three phase supply through larger more efficient distribution transformers in
Australia), the percentage of the lost energy due to distribution transformer
inefficiencies is much smaller in Australia;
• the MEPS as mandatory “minimum” standards do not allow for tolerances in
transformer losses. This has introduced additional commercial risks for
manufacturers;
• the MEPS does not take into account fact that some utilities require kiosk
transformers to be fully rated in the enclosure. Such units have much higher rating
outside of enclosure (and would be subject to higher efficiency requirements).
• MEPS requires much more extensive testing regime. The cost of these additional
tests will have to be borne by the manufacturers who will no doubt pass it on in
the final product costs. The RIS GWA (2002) does not include these costs into
cost-benefit analysis. The costs for additional tests are estimated to be $2,000 -
3,000 per unit/model, and the customized small series product lines might be
significantly affected by these additional costs.
In conclusion, it is recommended that the MEPS for distribution transformers are refined
by including:
• more rigorous analysis of MEPS levels;
• retrospective analysis of impacts of MEPS on distribution transformer prices. This
analysis should consider two separate components leading to price impact: changes
in manufacturing costs and commercial margin used to convert from
manufacturing costs to final price.
Chapter Seven: Performances of Distribution Transformers Installed in metallic enclosures – an Australian experience
7. PERFORMANCES OF DISTRIBUTION TRANSFORMERS INSTALLED

IN METALLIC ENCLOSURES – AN AUSTRALIAN EXPERIENCE
7.1. Introduction
In the last 20 years the Australian market is showing an increasing demand for packaged
substations with three phase distribution power transformers. Unfortunately, the standards
and regulations do not cover this area very well and in the last few decades the electrical
supply authorities and transformer manufacturers have developed different designs based
on unique specifications and distinctive combination of construction features. Most
factory assembled packaged substations currently used in Australia utilize metallic
enclosures, which include various types of ventilation systems. Those products evolved
over the last 30-35 years from the transformer substations developed by electrical utilities
in Victoria and New South Wales. The recently developed substations were designed
around modern, compact Medium Voltage switchgear (11 - 36 kV), fully enclosed Low
Voltage switchboards and largely customized, purpose-built, unique Australian distribution
transformers. Highly restrictive local environmental and urban planning regulations have
resulted in development of very compact packaged substations with extremely arduous
service conditions for built-in distribution transformers. The limited footprints and ever
increasing transformer ratings have resulted in reducing the ratio between the physical
dimensions of the installed distribution transformer and its rated power. This research is
focused on Australian oil-immersed, ONAN cooled and hermetically sealed distribution
transformers rated 150 to 2,500 kVA, highlighting their distinctive features: unique design,
superior loading capability, high reliability performances and safety features. The
assessment techniques discussed in previous chapters are developed for distribution
transformers operating “in free air” and no allowance is made for built-in distribution
transformers. This chapter provides information necessary for better understanding of
physical phenomena of thermal processes taking place during the operation of distribution
transformers installed in metallic enclosures, without being heavily involved in design
investigations.
7.2. Development of kiosk substations
IEC 61330 defines prefabricated substations as “type-tested equipment comprising
transformer, low-voltage and High-Voltage switchgear, connections and auxiliary
equipment in an enclosure to supply low-voltage energy from a high-voltage system”. The
packaged substations in Australia are better known as pad-mounted or kiosk substations.
They include MV switchgear (11 or 22 kV), a 22(11) kV/0.4 kV transformer (750 - 2,000
kVA) and an LV switchboard; all installed in a compact metallic enclosure. Some modern
substations also include communication, control and metering equipment. Design of kiosk
substations is a multifaceted process, which in addition to assessment of numerous
technical requirements (such as selection of equipment and consideration of requirements
for high availability of electrical power) also includes appraisal of safety aspects (for the
operators and the general public) as well as a variety of rigorous environmental and local
planning issues.
The new manufacturing methods developed around such a composite product and
implemented in Europe over the last few decades, are an evident example of a successful
concept of industrial dependability. In Europe, distribution power transformers and MV
and LV switchgear are fully standardized and type-tested “off-shelf” products and
development of uniform designs for kiosk substations based on such products is a logical
improvement path. The first IEC standard for pre-fabricated HV/LV substations was
published in 1995 (IEC 61330 Ed. 1.0 B, 1995). It specifies the service conditions, rated
characteristics, general structural requirements and test methods for “High-voltage/low
voltage prefabricated substations”, which include HV cable connections (up to 52 kV) and
distribution transformers up to 1,600 kVA.
Although the above standard has not become an Australian Standard yet, a number of
Australian electrical distribution companies have been discretely using this standard since
1997. Unfortunately, a strict application of the IEC recommendations for pre-fabricated
kiosk substations in Australia is not a straightforward exercise. The most complications are
due to highly customized Australian distribution transformers, which are designed for
specific users and conditions, resulting in extremely nonflexible solutions. In addition,
there is a range of differing requirements for loading of transformers installed in kiosk
substations. Most packaged kiosk substations are manufactured in very limited volumes,
they are not type-tested and very little technical data is publicly available.
7.3. Applicable Standards
In addition to IEC 61330 and other standards and technical regulations which
independently deal with all major parts of kiosk substations, there are Wiring Rules (2000),
an Australian standard, which covers the general aspects of electrical installations at all
voltage levels and as such also includes some requirements for MV/LV substations.
The Australian standard Loading guide for oil-immersed power transformers AS 2374.7-
1997, which is reproduced from an equivalent IEC standard - IEC 60354 Ed. 2.0 B (1991)
provides some recommendations for loading of distribution transformers when installed in
enclosures and buildings. Unfortunately, the data given in IEC 60354 is an excerpt from
the previous version of the Australian standard published in 1984 (Australian Standard AS
1078-1984) and does not include distribution transformers above 1,000 kVA.
7.4. Performance of Kiosk Transformers
7.4.1. Factors Affecting Life of Distribution Transformers
Distribution transformer life expectancy is a function of its design and components,
manufacturing techniques, operating conditions (including loading patterns, ambient
temperatures and network events) and maintenance policies. It is also a complex function
of many other more or less influential factors, which are usually an estimate only and
cannot be expressed explicitly and accurately (e.g. exact performances of the insulation
system). Although most Australian electrical utilities expect that an average design life for a
modern oil-immersed distribution transformer should be in excess of 20 - 30 years, this
fact does not constitute any expressed or implied warranty by manufacturers.
Climatic conditions other than exposure to higher temperatures (lightning, wind and air
pollution), uninterrupted system faults and physical damage by various external influences
are considered to be by far the greatest concern regarding the expected life of distribution
transformers in Australia. As distribution transformers are relatively inexpensive, very
reliable and easy to replace, they are expediently considered to be of much less critical
importance than larger power transformers and other parts of the power system. A
commonly applied methodology to install a slightly larger distribution transformer than
necessary and rely on its low load factor has resulted in acceptance of an unofficial policy
where distribution transformers require a reduced level of attention. It has been widely
accepted that the loading evaluation, although necessary, has no factual relevance to the
expected service lifetime of a distribution transformer. Consequently, there is very limited
information on the loading of distribution transformers in Australia.
Although the above principles are somewhat valid for smaller pole-mounted distribution
transformers (up to 500 kVA), the larger distribution transformers, as well as those
installed in kiosk substations require much more rigorous analysis of their service
conditions and respective loading capabilities. Firstly, there is a very emaciated possibility
of using non-optimal (increased) rating of those transformers due to material limits
imposed by the enclosure. Secondly, degradation of insulating materials caused by
increased ambient temperature due to restricted air flow around the transformer is
considered to be much more critical for its lifetime than the external influences. Finally,
the large distribution transformers in most cases supply loads which request very high
reliability of supply (e.g. hospitals, large residential blocks, commercial and industrial sites).
Reliability analysis of such transformers is much more complex than simply relying on a
quick replacement of a failed transformer.
7.4.2. Loading of Distribution Transformers
The maximum intermittent loading of distribution transformers for normal cycling, long-
term and short-term loading is vaguely defined in Australian Standard AS 2374.7-1997 as
1.5, 1.8 and 2.0 p.u. of the rated current respectively. Although, it is well known that
smaller transformers have generally better overloading capabilities, there is no
confirmation of that fact in Australian Standard AS 2374.7-1997, which recommends the
same loading limits for all power transformers below 2,500 kVA (defined as “distribution
transformers”).
The author of this thesis has tested a large number of distribution transformers and the
tests have shown that relative differences in thermal performances of distribution
transformers are due to designation to operate in “free air” or “enclosed” and due to
transformer size. The tests suggested that in addition to “free air” or “enclosed”
classification, distribution transformers should be further classified into four categories:
• small distribution transformers: below 500 kVA;
• medium distribution transformers: 750 - 1,000 kVA;
• large distribution transformers: 1,250 - 2,000 kVA.;
• very large distribution transformers: 2,500 kVA and above.
7.4.3. Design Features
Both standards’ series, Australian Standards 2374 and IEC Standards 60076, deal with oil-
immersed power transformers, which are installed in “free air”. If different service
conditions apply, such as restricted airflow around transformer’s cooling system when
transformer is “enclosed”, then transformer rating (and respective continuous and
intermittent loading limits) should be reduced to allow for departure from the prescribed
service conditions. The requirements in Australia are somewhat different, as the full name-
plate rating for distribution transformers is required for each application (in free air and in
an enclosure), forcing manufacturers to develop two completely different electrical designs
for the same nominal transformer rating.
In addition, the constructional features of Australian distribution transformers for kiosk
application are unique. Contrary to their European counterparts, distribution transformers
in Australia have bushings mounted on the side tank walls.
Due to size limits imposed on enclosures, the kiosk transformers are extremely compact
and usually very narrow and tall. Kiosk transformers have very low electrical losses and
they employ very efficient cooling systems (almost exclusively based on natural
ventilation). Modern Australian distribution transformers installed in kiosk substations are
very reliable, safe to operate and require very little maintenance. Most of them include an
oil containment, which prevents leakage of insulating oil outside of the enclosure.
Unfortunately, introduction of this “environmentally friendly” feature has further
burdened transformers as the oil containment in most cases restricts airflow inside the
enclosure.
7.4.4. Ambient Temperature
The thermal deterioration of the transformer insulation (as the most important factor for
loading considerations) is the function of the hot spot temperature and the top oil
temperature, which are dependant on ambient temperature.
The actual ambient temperature varies as function of the climate, the season, the time of
the day, etc. Table 13 from AS 2374.1 shows the maximum ambient temperatures defined
for standard oil-immersed distribution transformers in free-air operation:
TABLE 13 - NORMAL SERVICE CONDITIONS FOR TRANSFORMER OPERATING IN FREE AIR
Maximum ambient temperature 400C

Average daily ambient temperature 300C
Average yearly ambient temperature 200C
Australian kiosks employ both, the hermetically sealed and the free-breathing distribution
transformers. However, the users have given preferences to hermetically sealed
transformers due to their superior performances and very low maintenance requirements.
Those transformers are designed for top-oil temperature rise 60K (Kelvin) and average
winding temperature rise 65K.
Temperature limits for sealed distribution transformers with “A” thermal class of the
insulation system, assuming normal cyclic loading are presented in Table 14.
TABLE 14 - TEMPERATURE LIMITS FOR OIL-IMMERSED DISTRIBUTION TRANSFORMERS
Insulation system (top-oil temperature) 1050C

Rated hot-spot winding temperature 980C
Maximum permissible hot spot temperature 1400C
The above values do apply even if ambient temperatures are different to those in Table 13
(in Australian conditions demands for the maximum ambient temperature of 450C are not
rare) or if an operation inside the kiosk substation or building is required.
7.5. Impact of the Enclosure on Transformer Temperature Rises
The IEC standard IEC 61330 compares transformer top-oil temperature rise in an
enclosure and in free-air (for the same load) and the difference between those two values is
defined as “the temperature class of the enclosure“. It recommends three temperature
classes for the enclosure: 10K, 20K and 30K. In addition to its temperature class, the
enclosure is defined by its rated maximum power, i.e. the free-air rating of the largest
transformer, which fits into that enclosure. It is clearly stated that the maximum power,
expected to be delivered from the kiosk, is lower than the free-air rating of the
transformer. The correlation of the temperature class of the enclosure and the ambient
temperature is given in this example: a 20K class enclosure could release the full rating of
the transformer only at an ambient temperature of 00C (i.e. average yearly ambient
temperature 200C – 20K=00C). The Australian Standard AS 2374.7 recommends two
methods in assessing the impact of the enclosure on the transformer hot spot temperature
and the top oil temperature. The preferred (but not always feasible) method is to conduct
the factory temperature rise tests on the transformer installed in the enclosures. The
alternative method assesses the additional temperature rises experienced by the
transformer operating in the enclosure by measuring the temperature rise of air inside the
enclosure. It is suggested that half of the temperature rise of air inside the enclosure should
be added to the transformer top-oil temperature rise obtained by testing in free-air
operation. For example, an extra air-temperature rise in the kiosk-substation of 200C will
increase top oil temperature rise of the transformer by 100C. A variation of this method is
to correct transformer temperature rise by applying values for the temperature rise of air
inside the enclosure recommended in AS 2374.7.
Some of those recommended corrections are presented in Table 15.
TABLE 15 - CORRECTIONS FOR INCREASE IN AMBIENT TEMPERATURE DUE TO KIOSK

ENCLOSURE
Temperature increase in Transformer size (kVA)

ambient due to enclosure 250 500 750 1,000
0 0 0
10 C 15 C 20 C -
The author has thoroughly investigated both variations of the second method and it
appears that Table 3 in AS 2374.7, which provides recommendations for correction for
increase in ambient temperature due to the enclosure, should be extended by considering
the following:
• constructional features of enclosure, including equipment arrangement, ventilation
system and protection (IP) level (IEC 60529); for example, the tests have shown
that enclosures with a level of protection above IP24D (effective protection
against ingress of solid foreign objects with diameter larger than 12.5 mm, against
ingress of splashing water and against access to hazardous parts with a wire) cause
very high restrictions on airflow and uneven distribution of temperatures of
internal air;
• losses in transformer and switchgear; with a large number of transformer-
switchgear arrangements the range of losses released in the kiosk-substation could
be very wide. For example, a kiosk with a non-standard “high-loss” 750 kVA
transformer (AS 2374.1.2-2003) and a fully enclosed LV switchboard could have
higher total losses than a kiosk with an efficient “low-loss” 1,000 kVA transformer
and a “low-loss” switchgear;
• external conditions (solar radiation, wind, slope sites);
• larger distribution transformers (1,000 kVA-2,500 kVA);
• provision for enclosures manufactured from alternative materials.
Application of the second method by assessing impact of the enclosure on the extra
transformer top-oil temperature as 50% of the air temperature rise inside the enclosure is
very difficult, simply because it is not clear how and where to measure temperature inside
the enclosure. The analysis has also shown that the thermal classes for enclosures 10K,
20K and 30K, as recommended in IEC 61330 would not be the best solution for
Australian conditions. 30K class substations, where the top-oil temperature rise inside
enclosure is 300C higher than the top-oil temperature rise in free-air, would require very
expensive distribution transformers.
The authors suggest that the thermal classes for Australian conditions should be limited to
10K, 15K and 20K as the same output could be achieved more efficiently with an effective
ventilation system than with an over-designed transformer (AS 4388-1996). It seems that
most Australian users prefer the 15K temperature class enclosure. Incidentally, designs for
kiosk transformer for this type of enclosure appear to be the most economical under the
current set of technical specifications in Australia (AS 4388-1996).
7.6. Case Study
The author has thoroughly investigated features of a range of kiosk substations (300 kVA -
2,000 kVA) locally developed and installed in Australia.
7.6.1. Enclosure
Most Australian manufacturers claim that their prototype enclosures have been
successfully subjected to the full set of normal type tests. Some manufacturers offer a
special type test to assess the effects of arcing due to an internal fault. The constructions
features related to internal-arc tests have not been taken into account when assessing
thermal performances of distribution transformers, as at present time, there is no big
interest in the Australian market for kiosks with internal-arc containment features.
The kiosk-substations installed in Australia are very compact and fully outdoor-operated.
The kiosk contains of a metallic enclosure with transformer and switchgear compartments
and a base. Typically, the enclosure and compartments are made of 2.5 mm thick
galvanized mild steel sheets. Some versions utilize aluminium or stainless steel sheets. The
kiosk base is made of a reinforced concrete or hot-dip galvanized steel channels. The
transformer compartment is in the middle, completely segregated from the LV and the
MV switchgear compartments. Some kiosks include extensive ventilation and anti-
condensation systems, lift-off enclosure facilities and oil-containments.
The ventilation system include air baffles, air ducts, prefabricated air grilles, holes punched
in side-walls, outlet air openings above access doors in both switchgear compartments and
air-grilles in transformer compartment walls as shown in Figure 14.
Most manufacturers offer enclosures in three to four different sizes, covering transformer
sizes 300 to 2,500 kVA. Number of switching functions in MV compartment has
considerable impact on size of the enclosure, as most transformers have already been
“optimised” for kiosk application (i.e. significantly reduced in size comparing with ordinary
outdoor type distribution transformers).
FIGURE 14 - A TYPICAL METALLIC ENCLOSURE FOR KIOSK SUBSTATION WITH

VENTILATION OPENINGS ON SIDEWALLS
The standard required degree of protection for switchgear and transformer compartments
is IP24D. The safety margin is achieved by designing standard enclosure in such a way that
it is able to dissipate all heat generated inside and accumulated on its outside surfaces, for a
slightly higher level of protection (e.g. IP25D, which has a higher level of protection
against ingress of water). Ventilation openings are arranged to prevent any undesired
condensation on electrical equipment and inner wall surfaces. The optimum airflow is
achieved when the minimum quantity of heat dissipated by the transformer is discharged
in switchgear compartments. A simplified air temperature diagram along the sidewall for a
1,000 kVA kiosk-substation is shown in Figure 15. The measurements taken during the
temperature rise test show that the air temperature inside the enclosure is a mixture of
different temperatures and a complex function of the position (distances from the heat-
source, ventilation openings and air-flow barriers inside the enclosure). It is very difficult
to talk about “average” temperature inside the enclosure because of large temperature
divergences in all directions.
Temperature
0
( C)
60
45
30
MV
15 MV 3
TX 2 2.5
0 TX
2 TX 1 1.5 Length (m)
1.5
1 LV
0.5
0 0.5
Height (m)
FIGURE 15 - AIR TEMPERATURE IN A 1,000 KVA KIOSK METALLIC ENCLOSURE

MEASURED AT DISTANCE 50 MM FROM THE SIDE WALL (OUTSIDE AIR TEMPERATURE IS
18.80C)
The author adopted temperatures at two heights as relevant for transformer loading
assessment:
• Topheight (50mm below the kiosk ceiling);
• Midheight (approximately half of the internal height of the kiosk and 50 mm from
the sidewalls).
Typical temperature rises in a 1,000 kVA kiosk are shown in Figure 16. A simple
methodology to calculate air-temperature around the transformer inside enclosure based
on AS 4388-1996 has been developed. The calculated values are approximately 20C above
the measured values and as such provide a small safety factor in transformer loading
calculations.
Temperature
rise ( C)
0 Topheight
50 Midheight
40
30
20
10
0
Length (m)
0 0.5 1 1.5 2 2.5 3
LV TX TX TX MV MV
FIGURE 16 - TOPHEIGHT AND MIDHEIGHT TEMPERATURE RISES IN LOW VOLTAGE (LV),

TRANSFORMER (TX) AND MEDIUM VOLTAGE (MV) COMPARTMENTS
The fact that the increase in transformer top oil temperature rise by 60C halves its life (AS
1078-1984) emphasizes importance of an accurate forecast of air temperatures inside the
enclosure.
7.6.2. Transformer
Selection criteria for a distribution transformer are out of scope of this paper, and it has
been assumed that all factors, such as network performance, specific load requirements
and environmental considerations have been taken into account by selecting an
appropriate rating and suitable design. Table 16 presents data for a typical Australian oil-
immersed, ONAN distribution transformer designed for installation in kiosk substations.
TABLE 16 - TYPICAL DISTRIBUTION TRANSFORMER INSTALLED IN KIOSK SUSBTATION
Transformer data
Transformer rated power (in enclosure) kVA 1,000
Transformer total losses W 8,950
Transformer thermal time constant hours 3.7
LV compartment loss (typical) W 580
HV compartment loss (typical) W 300
Sun radiation (maximum) W/m2 980
Ventilation (inlets) m2 1.08
Ventilation (outlets) m2 1.20
0
Top oil temperature rise C 59
0
Average winding temperature rise C 63
0
Thermal gradient (average) C 14
0
Maximum ambient temperature C 40
0
Top-height temperature rise in transformer C 35
0
Mid-height temperature rise in transformer C 27
Pre-overload conditions
Load (% of rated power) % 75
0
Ambient temperature C 30
Overloading
Overload duration hours 2
Overload (% of rated power) % 145
0
Top oil temperature C 103
0
Hot spot temperature C 133
Bushings overload (short time) % 150
Continuous loading for various free air temperatures
Loading (% of rated power) at 100C % 112
Limiting the peak load to the transformer nameplate rating would result in an
uneconomical use of the transformer overload capability. Short-time peak overloads,
without significantly decreasing the life expectancy, are permitted (and very often
requested) from distribution transformers installed in kiosk substations.
While the loading of the transformer, during the overload, can increase rapidly, the oil
temperature increases more gradually with a time constant in the order of a few hours. The
temperature gradient between windings and oil reaches its ultimate value quickly, but the
slow rising temperature of cooler oil suppresses quick winding temperature rise. Hot-spot
temperatures considerably above 980C can be carried for short periods of time without
decreasing normal life expectancy, if this is offset by extended operation below 980C.
Table 17 compares overload requirements defined in AS 2374.7-1997 and capabilities of a
typical Australian kiosk transformer (24 hours cyclic loading, maximum ambient
temperature is 300C, duration of overload is 2 hours and preceding loading is 75% of the
rated power). The kiosk transformer is thermally optimised and has a low temperature
gradient and an increased thermal time constant. The difference between performances of
the average transformer and the transformer designed for kiosk application is obvious.
TABLE 17 - OVERLOAD CAPABILITIES IN % OF RATED POWER
Rating AS2374.7 Kiosk transformer

Requirements
1,000 kVA 130 % 145 %
7.7. CONCLUSION
The reliability of the entire LV network and thus most activities in residential, industrial
and commercial areas depends on the reliability of kiosk substations and their most
important part – the distribution transformer. Designing such an important part of
distribution network requires knowledge and control not only of the functioning of its
components, but also of the external influences to which they are subjected.
Most large distribution transformers in Australia are installed inside very compact metallic
enclosures. Those transformers are specially designed for such an application and have
thermal performances, which well exceed standard requirements. Classification of kiosk
enclosures as proposed by IEC 61330 has been reviewed and a narrower range of
temperature classes for enclosures has been suggested.
Loading of distribution transformers in kiosk-substations is not properly covered by the
Australian Standards. Recommendations given by IEC 61330 are not fully applicable for
Australian conditions. A design investigation was formulated to show the performance of
optimised distribution transformer designs when installed in kiosk-substations. Simple
methodology was developed to forecast temperature rises in transformer compartments at
two different levels: midheight and topheight of the transformer compartment. Heat run
tests confirmed calculated temperature rises under different overload conditions.
Comparison between data for average transformers given in AS 2374.7-1997 and thermally
optimised kiosk transformers confirmed the need to further investigate this topic. Future
analysis should also include assessment of improved designs and the total operating costs
for distribution transformers in kiosk substations.
Chapter Eight: Summary of Conclusions and Recommendations for Further Research
8. SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS FOR

FURTHER RESEARCH
8.1. Summary of Conclusions and Recommendations
Efficiency of distribution transformers is in range of 96 - 98.5% for standard models and
above 99% for high efficiency models and is relatively high in comparison with majority of
other machines and devices. However, as almost all electric power passes through
distribution transformers before it is consumed at its final destination (converted to
mechanical power, light or heat), the amount of energy, which distribution power
transformers dissipate is very high.
The Australian distribution networks employ about 670,000 distribution transformers and
about 19,000 new units are added to electrical distribution networks each year. It is
estimated that the average life of distribution transformers is in order of 25 years, and the
purchasing decisions based on poor assessment technologies and short-term objectives
will have lasting effects on future generations. Such a poor economic choice could be
avoided through introduction of new regulatory regime for minimum efficiency targets for
distribution transformers and application of an advanced assessment methodology.
Introduction of mandatory Minimum Energy Performance Standards for distribution
transformers in Australia has significantly helped to reverse the recent trends in purchasing
policies, which were focused on low initial costs. However, the new regulatory regime
should be supported by proven and accessible methodologies to optimise selection of
distribution transformers. This research offers a new solution for assessment of
distribution transformers based on:
• development of cost efficiency schedules for selected designs and representative
kVA ratings;
• thorough financial analysis of distribution transformer losses.
This refined methodology highlights importance of design and costing stages in the
assessment process. Further, it recommends moving from simple capitalisation of
transformer losses by extending evaluation of the total operating costs through
introduction of new evaluation factors based on life cycle cost concepts and on expected
service and loading conditions. The fact that Australian distribution transformers are
highly customized (designed for specific users and conditions) introduces additional
complexities into assessment process. The presented case study on pad-mounted
distribution transformers highlights importance of selecting proper kVA rating as well
inclusion of expected service and loading conditions into total assessment process.
8.2. Emerging Technologies for Distribution Transformers
This research project did not include the following design and technology options:
• special conductor materials, such as silver and high-temperature superconductors;
• amorphous core material;
• carbon composite materials for removal of heat;
• high-temperature insulating material;
• power electronics technologies.
The aim of this research is assess only technologies incorporated in commercially available
distribution transformers products, which are practical to manufacture, install, operate and
maintain. A recommendation for further research would be to include the working
prototypes, which are considered technologically feasible.
8.2.1. Silver as a Conductor Material
Although the use of silver as a conductor is technologically feasible (few distribution
transformers with silver windings were built in the USA during World War II due to war-
time lack of copper), this technology would be impracticable to implement. Silver has
superior electrical properties in comparison to copper, and at room temperature (250C),
however it has many limitations: high price, lower melting point, lower tensile strength and
limited availability.
8.2.2. High-Temperature Superconductors
The original application of low-temperature superconducting materials (LTS) cooled by
liquid helium has been improved by introduction of a new class of high-temperature
superconducting (HTS) materials in 1987 McConnel (2000). These new superconducting
materials use liquid nitrogen as a coolant, which is readily available and is considerably less
expensive than liquid helium. There are number of research programs launched worldwide
to explore use of HTS in power transformers. However, the use of superconductors in
transformer manufacturing is still considered to be in experimental stages.
These issues are identified as limiting factors for commercial use of superconductors in
production of distribution transformers:
• low-temperature superconductors are not feasible for commercial use due to
inability of conductors to return to the superconducting state following a high fault
current condition WEC (1982);
• high-temperature superconducting prototype built transformers include unique
extremely brittle conductors with unacceptable variation in losses and require
complex cryogenic support components.
Consequently, at this stage these transformers built on superconducting technology are not
considered to be technologically feasible and practicable to manufacture.
8.2.3. Amorphous Core Material in Stacked Core Configuration
There are very limited applications of amorphous materials in distribution transformer
cores. These materials have some obvious advantages: amorphous metals are extremely
thin, have very high electrical resistivity, have very small magnetic domain definition and
consequently no load losses in the distribution transformer cores made from these
materials are 60-70% lower than no load losses in conventional designs. However, these
cores saturate at only 1.57 Tesla (conventional low-silicon magnetic steels saturate at flux
levels of 2.08 Tesla) and they have higher excitation currents. In addition, fragility of this
material make amorphous transformer designs less space effective (they require larger
winding windows, and consequently have a space factor of only 85%, whilst the space
factor on conventional designs is 95 - 98%. Taking into account the above factors, the
final result would be a distribution transformer with lower no load losses, lower flux
density, higher space factor, larger core with greater load losses and higher production
costs. In addition, as discussed by Nadel (2001) amorphous material is considered a viable
core material only for wound-core arrangements. This material is not presently viable for
stacked core configurations.
8.2.4. Carbon Composite Materials for Heat Removal
An emerging technology that may improve future designs for distribution transformers is
the use of carbon fibre composite materials for heat removal. In addition to excellent
electrical insulation performances, these materials are very good heat conductors. The first
prototype suggests possibility of reducing size and core losses by 35% DOE Screening
Analysis (2001). Unfortunately, this technology is not feasible for larger distribution
transformers. It seems that this technology is still be several years away from
commercialisation.
8.2.5. High-Temperature Insulating Material
The transformer industry is currently investigating several high temperature insulating
materials. The aim is to create an electrical insulation that can withstand higher operating
temperatures, which can conduct heat more effectively out of the core-coil assembly.
Improved electrical insulation performances would result in smaller transformer volumes
and consequently in lower losses. Unfortunately, this technology is not yet commercially
feasible.
8.2.6. Power Electronics Technology
The application of power electronics technology for power transformers is in the early
stages of development. A small transformer was built at Purdue University DOE Screening
Analysis (2001), however no distribution transformer prototype has ever been
manufactured using this technology.
8.3. Recommendations for Further Research
Recommendations for further research include:
• extension of the scope of research to include wider range of distribution
transformers (single phase distribution transformers and dry type distribution
transformers);
• assessment of emerging technologies and analysis of alternative design solutions;
• comprehensive assessment of impacts on environment;
• more inclusive analysis of impacts of new assessment methodologies on
distribution utilities;
• it is recommended that the MEPS for distribution transformers are refined by
including more rigorous analysis of retrospective analysis of impacts of MEPS on
distribution transformer prices. This analysis should consider two separate
components leading to price impacts: changes in manufacturing costs and
commercial margin used to convert from manufacturing costs to final price.
Chapter Nine: Publications
9. PUBLICATIONS
No Authors Title Conference /

Proceedings
1. M. All- DISTRIBUTION NETWORK AUPEC’96
Dabbagh BEHAVIOUR UNDER DIFFERENT Melbourne 1996
S. Corhodzic GROUNDING CONDITIONS
2. S. Corhodzic THERMAL CHARACTERISTICS OF AUPEC’98

OIL-IMMERSED DISTRIBUTION Hobart
TRANSFORMERS INSTALLED IN 1998
PADMOUNTED SUBSTATIONS
3. A. Kalam LOADING OF OIL-IMMERSED INT-PEC’99

S. Corhodzic DISTRIBUTION TRANSFORMERS Churchill, Vic
INSTALLED IN PADMOUNTED 1999
KIOSK SUBSTATIONS
4. A. Kalam ASSESSMENT OF DISTRIBUTION AUPEC

S. Corhodzic TRANSFORMERS USING LOSS /EECON’99
CAPITALISATION FORMULAE Darwin
1999
5. A. Kalam ASSESSMENT OF DISTRIBUTION Journal of
S. Corhodzic TRANSFORMERS USING LOSS Electrical and
CAPITALISATION FORMULAE Electronic
Engineering
Australia,
Issue May 2000
Chapter Nine: Publications
6. A. Kalam ANALYSIS OF LOSS IEEE/PowerCon

S. Corhodzic CAPITALISATION FORMULAE 2000
USED FOR ASSESSMENT OF Perth
AUSTRALIAN DISTRIBUTION 2000
TRANSFORMERS
7. A. Kalam DEVELOPMENT OF UNIVERSAL DISTRIBUTION

S. Corhodzic STEP-UP TRANSFORMER FOR 2003
TASMANIAN POWER STATIONS Adelaide
2003
8. A. Kalam PERFORMANCES OF IEEE
S. Corhodzic DISTRIBUTION TRANSFORMERS Transactions on
INSTALLED IN METALLIC Power Delivery
ENCLOSURES – AN AUSTRALIAN July, 2005
EXPERIENCE
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Appendices
APPENDICES
APPENDIX 1 - DISTRIBUTION TRANSFORMERS – TYPICAL PRODUCT
DATA
Table A1-1 Single Phase Distribution Transformers Registered with Australian Greenhouse
Office (Energy Efficiency) – Status: January 2005
Manufacturer Model Network Rated Output High
Voltage kV kVA Efficiency
D217 22 25 -
D240 11 15 -
D241 11 30 -
D216 22 16 -
D218 22 25 -
ETEL D242 22 50 -
D253 11 10 -
D252 22 10 -
D254 11 25 -
D255 11 50 -
X015NGS3F 11 15 -
X030NGS3G 11 30 -
X050NGS3G 11 50 -
ABB 50kVA, LW,LS 11 50 -
Transformers 10kVA, LW,LS 11 10 -
16kVA, LW,LS 11 16 -
25kVA, LW,LS 11 25 -
Tyree 50M2A-B 22 50 -
Transformers 25M2A-B 22 25 -
Aust. Pty Ltd 25M7A-A 22 25 -
16M1A-C 11 16

Appendices
Table A1-2 Three Phase Distribution Transformers Registered with Australian Greenhouse
Office (Energy Efficiency) – Status: January 2005
Manufacturer Model Network Rated High
Voltage kV Output kVA Efficiency
MG2000 11 2000 -
MG400 11 400 -
MG500 11 500 -
MG600 11 600 -
MG750 11 750 -
MG800 11 800 -
Schneider MG1000 11 1,000 -
Electric MG300 22 300 -
(Australia) Pty MG1500 11 1,500 -
Limited MG200 22 200 -
MG2500 11 2,500 -
MG1250 11 1,250 -
MG315 22 315 -
MG100 22 100 -
MG160 22 160 -
500M4B 11 500 -
Tyree 200M5B-C 22 200 YES
Transformers 100M4A 11 100 YES
Aust. Pty Ltd 25M4A-C 11 25 -
315M5B-B 22 315 -
63M5A-B 22 63 -
400M4B-C 11 400 YES
100KVA 11 1,000 YES
1500KVA 11 1,500 YES
750KVA 11 750 YES
Wilson 500KVA 11 500 YES
Transformers 315KVA 11 315 YES
Co. Pty Ltd 200KVA 22 200 YES
2000KVA 11 2,000 -
100KVA 11 100 -
X300PHM3B 22 300 -
XK10NHM3F 11 1,000 -
X030NHW3F 11 30 -
X050NHW3G 11 50 -
ABB X075NHW3G 11 75 -
Transformers X100NHW3H 11 100 -
X150NHW3B 11 150 -
X200NHW3F 11 200 -
X300NHM3M 11 300 -
X750NHM3F 11 750 -

Appendices
X500PHM3A 22 500 -
HK15NKM2A 11 1,500 -
X050PHW3C 22 50 -
X075PHW3B 22 75 -
X150PHW3A 22 150 -
X200PHM3B 22 200 -
X500NHM3N 11 500 -
25KVA, LW,LS 11 25 -
63KVA, LW,LS 11 63 -
100KVA, LW,LS 11 100 -
ABB 200KVA, LW,LS 11 200 -
Transformers 315KVA, LW,LS 11 315 -
500KVA, LW,LS 11 500 -
750KVA, LW,LS 11 750 -
1000KVA, LW,LS 11 1,000 -
1500KVA, LW,LS 11 1,500 -
2000KVA, LW,LS 11 2000 -
XK10PHM3B 22 1,000
XK20NHM3E 11 2,000 -
D221 22 63 -
D222 22 100 -
D250 22 200 -
D232 22 315 -
D224 22 200 -
D243 11 15 -
ETEL D214 11 750 -
D098 11 500 -
D215 11 1,000 -
D206 11 30 -
D207 11 50 -
D208 11 75 -
D209 11 100 -
D210 11 150 -
D211 11 200 -
D212 11 300 -
Appendices
AREVA Ultra-compact liquid filled distribution transformer (Siltrim)

Table A1-3 Ratings and dimensions
1,600 kVA 2,000 kVA 2,300 kVA

Rated voltage kV 20 20 20
No Load Losses kW 2.0 2.4 2.5
Load Losses (at 120 °C) W 13,000 18,000 19,000
Impedance (at 120 °C) % 6 6 6
Length (l) mm 1,992 2,110 2,245
Width (w) mm 770 770 770
Height (h) mm 1,676 2,040 2,125
Total weight kg 3,430 4,400 5,580
Description
There are increasing requirements for a distribution transformer that can fit into compact
volumes such as inside wind turbine towers. Until recently, the solutions available came
with a significant compromise: a rising winding temperature. This resulted in reduced life
expectancy and overheated environment for the surrounding power electronics and low-
voltage equipment. Areva has developed an innovative, highly technically advanced
solution, SILTRIM distribution transformer. That patented design allows to retain low
winding temperature despite transformers extremely compact size. SILTRIM is specifically
built for complex mechanical & electrical environments and is installable in the harshest
environmental locations, meeting the demand for up to 2.3 MVA and 20 kV.
Advantages
• Long life cycle, compact, fire resistant, explosion-proof;
• Designed for high harmonics environment and overload conditions;
• Low heat dissipation;
• Near-zero maintenance, recyclable;
• Further resistance to vibration with optional vibration pads;
• Highest level of availability and reliability.

Appendices
It is test-proven for extremely high level of over-voltage and is equipped with a pressure-
relief device as additional safety measure against explosion. It offers lower winding
hotspot temperatures resulting to longer working life with high availability and reliability.
SILTRIM handles high harmonics environment and overload conditions. It is designed
to provide protection against over- fluxing, through its correct application of operating
flux density and use of magnetic core material.
Performances and Application Field

The high level of SILTRIM’s performance (higher efficiency, low temperature rise, fire
resistance) combined with its compactness is obtained by using excellent heat dissipation
dielectric such as silicon oil or Midel.
The SILTRIM transformer is ideally suited for installation in wind turbines towers,
compact sub-stations, on-and off-shore platforms. Extremely compact, it fits into
reduced spaces and remains cool. It offers lower winding hotspot temperatures
resulting to longer working life with high availability and reliability.
Appendices
TPC liquid filled distribution transformer – Typical modern European distribution transformer
Table A1-4 Technical Data
Ground
Type
mounted
Pole-mounted Ground-mounted
reduced
noise level
Rated
kVA 50 100 160 100 160 250 250
power
Rated
primary kV 15 or 20 20
voltage
Off load tap
% ± 2.5 by step of 2.5 %
changing
Operating
24 / 50
volts/Test kV 17.5 / 38 / 95 or 24 /50 / 125
/125
volts/BI L
Off load
410 off load between phases,
secondary V
237 between phases and neutral
voltage
Vector group
symbol Yzn11 Dyn11 Dyn11 Dyn11 Dyn11 Dyn11 Dyn11
No Load Losses (W) 125 210 375 210 375 530 460
Load Losses
1,350 2,150 3,100 2,150 3,100 4,200 4,000
(W) - (75°C)
Impedance Ucc
4 4 4 4 4 4 4
voltage %
No-load
Io% 1 1 1.5 1 1.5 1 2.1
current
Acoustic
power dB(A) 49 57 49 57 60 44
LWA
Appendices
Table A1-5 Dimensions and Weights
Ground
mounted
Type Pole-mounted Ground-mounted reduced
noise
level
Rated power kVA 50 100 160 100 160 250 250
Length mm 935 1,125 115 914 894 1,200 1,174
Width mm 730 730 780 730 770 800 779
Height mm 1,044 1,140 1,193 1,027 1,083 1,300 1,410
Total weight kg 390 476 549 515 615 974 1,095
Mineral oil
weight kg 129 132 117 133 148 270 274
Product Description
• Three-phase totally filled and hermetically sealed mineral oil immersed
distribution transformer;
• Pole-mounted: 50, 100, 160 kVA; ground-mounted: 100, 160 and 250 kVA;
• Primary voltages 15 or 20 kV;
• Secondary voltage 410 V;
• Frequency 50 Hz;
• Equipped with a built-in protection shut down system.
Advantages
The TPC is a new technical generation of distribution transformers. It offers reaction to
every type of failure that may occur by ensuring systematic disconnection of the HVA
network. The TPC has its own HV protection so that in the case of a fault it disconnects
itself from the grid without tripping the HV protection devices of the source substation,
and without generating any abnormal LV voltage. It doesn’t explode and it doesn’t
Appendices
pollute. It avoids HV network disruptions. Integration of a patented protection and

disconnection system with fuse interruption of the power means: power interruption
occurs within 20 msec (which cannot be done with a switch). This protection system is
equipped with a locking device which avoids operation of the short-circuit system during
transport and handling operations. This model is interchangeable with transformers of
earlier technical generations. This transformer has same conventional components and
characteristics as the previous models (i.e. similar tank design and compatibility with
existing LV protection systems). The TPC can be used to replace a conventional
transformer of an earlier technical generation (HN 52-S-20 EDF specification) without
modifying the installation. The differences are in the on-load connection of HVA
bushings for pole-mounted transformers and reduced overall dimensions (for example, a
250 kVA TPC is smaller than a 160 kVA EDF HN 52-S-20).
Application Field
The TPC is mainly dedicated to pole-mounted or ground mounted new installations in
substations, renewal of transformers and installations in sensitive areas (e.g. fire risk, high
level of pollution, high traffic areas etc.)
Protection System
• 2 HVA fuses;
• 2 micro fuses together with 2 strikers;
• 1 three-phase short-circuit system;
• 1 pressure detector;
• 1 oil level detector associated to a striker;
• in addition, the connections and coils insulation have been reinforced to avoid the
risks of electrical earth faults.
Main Components
• 1 locking system of the short-circuiting switch (to be used during transport and
handling);
• 1 HVA off-load tap changer;
Appendices
• 1 filling hole;
• 1 rating plate;
• 2 lifting lugs;
• 1 device for earth continuity between tank and cover;
• 1 M12 earthing bolt;
• anti-corrosion tank treatment;
• RAL 7033 final standard paint.
Pole-mounted type
• 3 synthetic HVA bushings 24 kV / 250 A fitted with insulated bird-proof
terminals that allow live connection;
• these bushings are in accordance with seaside installation conditions (extended
creepage distance);
• 4 LV porcelain bushings 1 kV / 250 A;
• 1 standard mounting device.
Ground-mounted type
• 3 HVA plug-in bushings 24 kV / 250 A fixed parts;
• 4 LV porcelain bushings 1 kV / 250 A up to 160 kVA fitted with 4 individual
flexible PVC sheaths (IP2X IK07);
• 4 LV busbars for 250 kVA fitted with 4 individual flexible PVC sheaths (IP2X
IK07 that allow connection of 1 or 2 cables);
• 4 rollers.
Appendices
APPENDIX 2- SUMMARY OF AS FOR POWER TRANSFORMERS
AS 2374.1-1997 POWER TRANSFORMERS - GENERAL
Scope
This part of International Standard IEC 76 applies to three-phase and single-phase
power transformers (including auto-transformers) with the exception of certain
categories of small and special transformers such as:
• single-phase transformers with rated power less than 1 kVA and three-phase
transformers less than 5 kVA;
• instrument transformers;
• transformers for static converters;
• traction transformers mounted on rolling stock;
• starting transformers;
• testing transformers;
• welding transformers.
When IEC standards do not exist for such categories of transformers, this part of IEC
76 may still be applicable either as a whole or in part. For those categories of power
transformers and reactors which have their own IEC standards, this part is applicable
only to the extent in which it is specifically called up by cross-reference in the other
standard. At several places in this part it is specified or recommended that an 'agreement'
shall be reached concerning alternative or additional technical solutions or procedures.
Such agreement is to be made between the manufacturer and the purchaser. The matters
should preferably be raised at an early stage and the agreements included in the contract
specification.
Abstract
Specifies the technical requirements for single and three-phase power transformers,
including auto transformers, but excludes single-phase transformers rated at less than 1
kVA, three-phase transformers rated at less than 5 kVA, and certain special transformers
such as instrument, starting, testing and welding transformers, transformers for static
converters and those mounted on rolling stock. Based on but not equivalent to and has

Appendices
been reproduced from IEC 76-1:1993. Includes Australian variations such as commonly
used power ratings and preferred methods of cooling, connections in general use, and
details regarding connection designation.
History
• First published as part of AS C61-1931;
• Second edition 1946;
• Third edition 1963;
• Fourth edition 1970;
• Revised and redesignated in part as AS 2374.1-1982 and AS 2374.4-1982;
• AS 2374.1-1982 and AS 2374.4-1982 revised, amalgamated and designated AS
2374.1-1997.
AS 2374.1.2-2003: POWER TRANSFORMERS - MINIMUM ENERGY

PERFORMANCE STANDARD (MEPS) REQUIREMENTS FOR
DISTRIBUTION TRANSFORMERS
Scope
This standard applies to dry-type and oil-immersed type, three-phase and single-phase
power transformers with power ratings from 10 kVA to 2,500 kVA and system highest
voltage up to 24 kV. This standard does not apply to certain categories of special
transformers such as
• transformers other than those on 11 or 22 kV networks;
• auto transformers;
• welding transformers;
• three phase transformers with three or more windings per phase;
• arc-furnace transformers;
• earthing transformers;
Appendices
• rectifier or converter transformers;

• uninterruptible power supply (ups) transformers;
• transformers with an impedance less than 3% or more than 8%;
• voltage regulating transformers;
• transformers designed for frequencies other than 50 Hertz;
• gas-filled dry-type transformers;
• flame-proof transformers.
Abstract
Specifies minimum power efficiency levels and high power efficiency levels for oil-
immersed and dry-type distribution transformers, with power ratings from 10 kVA to
2500 kVA, intended to be used on 11 kV and 22 kV networks. It is expected that this
Standard will be called into legislation by individual States and Territories mandating
these requirements under Minimum Energy Performance Standard (MEPS) regulations.
History
• First published as AS 2374.1.2-2003.
AS 2374.2-1997: POWER TRANSFORMERS - TEMPERATURE RISE
Scope
This part of International Standard IEC 76 identifies transformers according to their
cooling methods, defines temperature-rise limits and details the methods of test for
temperature-rise measurements. It applies to transformers as defined in the scope of
IEC 76-1.
Abstract
Specifies temperature-rise limits and methods of test for measuring temperature rise.
Based on but not equivalent to, and has been reproduced from IEC 76-2:1993.
Includes Australian variations.
History
Appendices
• Second edition 1946;

• Revised and redesignated in part as AS 2374.2-1982;
• Second edition 1997.
AS 2374.3.0-1982: POWER TRANSFORMERS - INSULATION LEVELS AND

DIELECTRIC TESTS - GENERAL REQUIREMENTS
Scope
This standard specifies the insulation levels and dielectric tests for power transformers.
Abstract
Specifies the insulation levels and dielectric tests for power transformers as defined in
AS 2374.1. Based on IEC 76-3.
AS 2374.3.0-1982/AMDT 1-1992: POWER TRANSFORMERS - INSULATION

LEVELS AND DIELECTRIC TESTS
AS 2374.3.1-1992: POWER TRANSFORMERS - INSULATION LEVELS AND

DIELECTRIC TESTS - EXTERNAL CLEARANCES IN AIR
Abstract
Sets out minimum clearances in air between live parts of bushings on oil-immersed
power transformers and objects at earth potential. The text has been reproduced from
IEC 76-3-1:1987 and the tabulated minimum clearances have been modified.
History
• First published as AS 2374.3.1-1992.
AS 2374.5-1982: POWER TRANSFORMERS - ABILITY TO WITHSTAND

SHORT-CIRCUIT
Scope
This standard specifies the design of power transformers as defined in AS 2374, Part 1,
and the requirements necessary both in regard to their ability to withstand short-circuit
and the means of demonstrating that ability.
Appendices
NOTES:
1. Pending the publication of a standard that applies to dry-type transformers, the
requirements of this standard may be applied to dry-type transformers subject to
agreement between the purchaser and the manufacturer and taking into account the
principles established in Sections 2 and 3.
2. A reduced schedule of short-circuit tests may be applied to Category I transformers by
agreement between purchaser, manufacturer and testing authority. Guidance on the
reduced schedule is given in Appendix A.
Abstract
Specifies the design of power transformers as defined in AS 2374.1, and the
requirements necessary both in regard to their ability to withstand short-circuit and the
means of demonstrating that ability. Based on IEC 76-5.
AS 2374.6-1994: POWER TRANSFORMERS - DETERMINATION OF

TRANSFORMER AND REACTOR SOUND LEVELS
Scope
This standard defines the methods by which the sound levels of transformers, reactors
and their associated cooling equipment shall be determined so that compliance with any
specification requirements may be confirmed and the characteristics of the noise emitted
in service determined.
This standard is intended to apply to measurements made in the manufacturer's works
since conditions may be very different when measurements are made on site because of
the proximity of other objects, background extraneous noises, etc. Nevertheless, the
same general rules as are given herein may be followed when on-site measurements are
made.
In those cases where sufficient power is available in the factory to permit full
energisation of reactors, the methods to be followed are the same as for transformers.
Such measurements shall be made by agreement between the manufacturer and the
purchaser. Alternatively, measurements may be made on site where conditions are
suitable.
Appendices
The methods are applicable to transformers and reactors covered by IEC Publications
76, 726 and 289, without further limitation as regards size or voltage and when fitted
with their normal auxiliary equipment, inasmuch as it may influence the measurement
result. Although the following text refers only to transformers, it is equally applicable to
reactors provided that it is recognized that the current taken by a reactor is dependent on
the voltage applied and, consequently, that a reactor cannot be tested at no-load.
This standard provides a basis for calculation of sound power levels.
The methods of measurement and the environmental qualification procedure given in
Appendix A are in accordance with ISO Standard 3746. Measurements made in
conformity with this IEC standard tend to result in standard deviations which are equal
to or less than 3 dB.
Abstract
Defines sound power versus sound pressure and sets out the methods by which the
sound power levels of transformers, reactors, and their associated cooling equipment
shall be determined. Standard and reduced sound power level limits for transformers
only have been added in an Australian Appendix. Technically equivalent to IEC
551:1987, with the addition of Appendix AA.
History
• Second edition 1946 (endorsement of BS 171-1936 with amendments);
• Revised and redesignated in part as AS 2374.6-1982;
• Second edition 1994.
AS 2374.6-1994/AMDT 1-2000: POWER TRANSFORMERS

DETERMINATION OF TRANSFORMER AND REACTOR SOUND
LEVELS
AS 2374.7-1997: POWER TRANSFORMERS - LOADING GUIDE FOR OIL-

IMMERSED POWER TRANSFORMERS
Appendices
Scope
This guide is applicable to oil-immersed transformers complying with IEC 76. It
indicates how, within limits, transformers may be loaded above rated conditions. For
furnace transformers, the manufacturer should be consulted in view of the peculiar
loading profile.
Abstract
Provides guidance on determining the acceptable relationship between transformer
rating and proposed load cycle when considering the effect of operating temperatures on
life expectancy due to insulation deterioration and thermal ageing. Includes
recommendations for loading above the nameplate rating and guidance for choosing
appropriate rated quantities and loading conditions for new installations. It applies to the
same range of transformers complying with AS 2374.1-1997. This Standard is technically
equivalent to and reproduced from IEC 354:1991 and includes Australian informative
appendices on determination of the thermal time-constant and indirect measurement of
winding hot-spot temperature.
History
• First published as AS CC10-1965;
• Revised and redesignated AS 1078.1-1972;
• Revised and redesignated AS 1078-1984;
• Revised and redesignated AS 2374.7-1997;
AS 2374.7-1997/AMDT 1-1998: POWER TRANSFORMERS - LOADING

GUIDE FOR OIL-IMMERSED POWER TRANSFORMERS
AS 2374.8-2000: POWER TRANSFORMERS - APPLICATION GUIDE
Scope
This Standard applies to power transformers complying with the series of publications
IEC 60076.
It is intended to provide information to users about:
• certain fundamental service characteristics of different transformer connections
and magnetic circuit designs, with particular reference to zero-sequence
phenomena;
Appendices
• system fault currents in transformers with YNynd and similar connections;

• parallel operation of transformers, calculation of voltage drop or rise under load,
and calculation of load loss for three-winding load combinations;
• selection of rated quantities and tapping quantities at the time of purchase, based
on prospective loading cases;
• application of transformers of conventional design to convertor loading;
• measuring technique and accuracy in loss measurement.
Part of the information is of a general nature and applicable to all sizes of power
transformers. Several chapters, however, deal with aspects and problems which are of
the interest only for the specification and utilization of large high-voltage units. The
recommendations are not mandatory and do not in themselves constitute specification
requirements. Information concerning loadability of power transformers is given in IEC
60354, for oil-immersed transformers, and IEC 60905, for dry-type transformers.
Guidance for impulse testing of power transformers is given in IEC 60722.
Abstract
Provides a guide for the application, calculations and measurements of conventional
design and loaded three-phase and single-phase power transformers (including auto-
transformers). Certain categories of small and special transformers are not covered.
Recommendations are not mandatory and do not in themselves constitute specification
requirements.
History
• First published as AS 2421-1981;
• Revised and redesignated as AS 2374.8-2000.
Appendices
APPENDIX 3 - SUMMARY OF KEY DOCUMENTS
http://www.energyrating.gov.au/considered.html#transformers
NAEEEC introduced MEPS for certain distribution transformers on 1 October 2004.

Details are contained in the MEPS profile and Regulatory Impact Statement (see below)
and in AS 2374.1.2-2003. The following reports have been released for distribution
transformers:
• MEPS Technical Report – Distribution Transformers, detailed technical report
by Mark Ellis & Associates gives data on market, overseas programs, emissions,
test procedures and program options (published in March 2000);
• MEPS Profile – Distribution Transformers: proposes MEPS levels for a range of
distribution transformers which operate on 11k and 22kV systems from 10kVA
to 2500 kVA (published in March 2001):
• Regulatory Impact Statement: MEPS for Electricity Distribution Transformers,
Report 2001/18 (published in February 2002).
MEPS – Analysis of Potential for Minimum Energy Performance Standards for

Distribution Transformers
Author: Mark Ellis & Associates, March 2000

Location: http://www.energyrating.gov.au/library/detailstech-transform2000.html
Prepared for the Australian Greenhouse Office by Mark Ellis & Associates with the
assistance of Professor Trevor Blackburn (UNSW). Final Report, March 8th, 2000.
Gives data on market, overseas programs, emissions, test procedures and program
options. Concentrates on MEPS for distribution transformers, which operate on 11 kV
and 22 kV systems from 10 kVA to 2,500 kVA; includes liquid filled and dry type.
MEPS Profile – Distribution Transformers
Author: NAEEEC, March 2001

Location: http://www.energyrating.gov.au/library/detailsprofile-transform2001.html
Proposes MEPS levels for a range of distribution transformers, which operate on 11k
and 22kV systems from 10kVA to 2500 kVA; includes liquid filled and dry type. Sets out
Appendices
the timetable for public consultation in the development of the new MEPS levels.
Regulatory Impact Statement: Minimum Energy Performance Standards and

Alternative Strategies for Electricity Distribution Transformers
Authors: George Wilkenfeld and Associates, January 2002

Location: http://www.energyrating.gov.au/library/details200218-transformers.html
Electricity distribution transformers are essential for the operation of the electricity
system. Their function is to step the supply voltage down from transmission voltages of
33,000 volts and above to the 415 volt three-phase supply which most electricity users
receive (a single phase of this supply is 240 volts). Industry sources estimate that there
are about 577,000 utility-owned distribution transformers in use in Australia, and their
number is increasing at about 1.5% per annum.
The proposal is to introduce mandatory minimum energy performance standards for all
electricity distribution transformers of up to 2500 kVA capacity, falling within the scope
of a proposed new part of Australia Standard AS2374-1-2 2001: Power Transformers:
minimum energy performance standards for distribution transformers. They are
expressed in terms of minimum efficiency levels at half rated load. It is recommended
that: States and Territories implement the proposed mandatory minimum energy
performance standards. The mode of implementation should be through amendment of
the existing regulations governing appliance energy labelling and MEPS in each State and
Territory. The amendments should:
• add electricity distribution transformers to the schedule of products for which
minimum energy performance standards are required, and refer to the MEPS
levels in Tables 1 and 2 of AS 2374.1.2 (proposed part);
• add electricity distribution transformers to the schedule of products requiring
energy labelling, so that any transformer for which the claim of “high efficiency”
or “energy efficient” are made must meet the energy efficiency criteria in Tables
3 and 4 of AS2374.1.2 (proposed part);
• require registration of models, so invoking Appendix A of the proposed
Standard;
Appendices
• allow transformers manufactured or imported prior to the date of effect of the

regulations to continue to be lawfully sold indefinitely.
Governments will make the register of electricity distribution transformer characteristics
publicly accessible, so prospective purchasers can compare their energy efficiencies.
MEPS Requirements for Distribution Transformers
Author: NAEEEC, March 2001

Location: http://www.energyrating.gov.au/transformers2.html
From 1 October 2004, distribution transformers manufactured in or imported into
Australia must comply with Minimum Energy Performance (MEPS) requirements which
are set out in AS 2374.1.2-2003. The scope of transformer MEPS covers oil-immersed
and dry-type distribution transformers with power ratings from 10 kVA to 2500 kVA
intended to be used on 11 kV and 22 kV networks. The intention of MEPS is to increase
energy efficiency by eliminating low efficiency transformers from the market and to
encourage the use of high efficiency transformers. The standard also defines minimum
efficiency levels for “High Power Efficiency Transformers”. Only products, which meet
the specified efficiency levels can apply this term to promotional or advertising materials.
Transformers within the scope of MEPS are required to have on their rating plate a
statement that indicates compliance with AS 2374.1.2.
The Minimum Energy Performance Standards (MEPS) for distribution transformers are
set out as power efficiency levels at 50% of rated load in AS 2374.1.2 when tested in
accordance with AS 2374.1 or AS 2735, as applicable.
MEPS does not apply to the following types of transformers:
• transformers other than those on 11 kV or 22 kV networks;
• auto transformers;
Appendices
• welding transformers;
• three phase transformers with three or more windings per phase;
• arc-furnace transformers;
• earthing transformers;
• rectifier or converter transformers;
• uninterruptible power supply (UPS) transformers;
• transformers with an impedance less than 3% or more than 8%;
• voltage regulating transformers;
• transformers designed for frequencies other than 50 Hz;
• gas-filled dry-type transformers; or
• flame-proof transformers.
MEPS Levels
MEPS levels, set out as minimum power efficiency levels at 50% of rated load for various
transformer types, are set out below. Reference should be made to AS 2374.1.2-2003 for
detailed conditions and test methods.
Appendices
Table A3-1 Minimum Power Efficiency Levels for Oil-Immersed Transformers
Type kVA Power efficiency @ 50%

load
10 98.30
16 98.52
Single phase and SWER
25 98.70
50 98.90
25 98.28
63 98.62
100 98.76
200 98.94
315 99.04
Three phase 500 99.13
750 99.21
1,000 99.27
1,500 99.35
2,000 99.39
2,500 99.40
Appendices
Table A3-2 Minimum Power Efficiency Levels for Dry-Type Transformers
Type kVA Power efficiency @ 50% load

Um=12 kV Um=24 kV
10 97.29 97.01
16 97.60 97.27
25 97.89 97.53
50 98.31 97.91
25 97.17 97.17
63 97.78 97.78
100 98.07 98.07
200 98.46 98.42
315 98.67 98.59
Three phase 500 98.84 98.74
750 98.96 98.85
1,000 99.03 98.92
1,500 99.12 99.01
2,000 99.16 99.06
2,500 99.19 99.09
Appendices
High Power Efficiency Levels

Table A3-3 High Power Efficiency Levels For Oil-Immersed Transformers
Type kVA Power efficiency @ 50%

load
10 98.42
16 98.64
25 98.80
50 99.00
25 98.50
63 98.82
100 99.00
200 99.11
315 99.19
Three phase 500 99.26
750 99.32
1,000 99.37
1,500 99.44
2,000 99.49
2,500 99.50
Minimum efficiency levels for “High Power Efficiency Transformers, set out as minimum
power efficiency levels at 50% of rated load for various transformer types, are set out in
Table A3-3. Reference should be made to AS 2374.1.2-2003 for detailed conditions and
test methods.
Appendices
Table A3-4 Table High Power Efficiency Levels for Dry-Type Transformers
Type kVA Power efficiency @ 50% load

Um=12 kV Um=24 kV
10 97.53 97.32
16 97.83 97.55
25 98.11 97.78
50 98.50 98.10
25 97.42 97.42
63 98.01 98.01
100 98.28 98.28
200 98.64 98.60
315 98.82 98.74
Three phase 500 98.97 98.87
750 99.08 98.98
1,000 99.14 98.04
1,500 99.21 99.12
2,000 99.24 99.17
2,500 99.27 99.20
Note: For intermediate power ratings the power efficiency level shall be calculated by
linear interpolation.
Appendices
APPENDIX 4 - SCALING RULES FOR DISTRIBUTION TRANSFORMERS
Theoretical Analysis of Scaling Factors
The certain fundamental relations between distribution transformers’ ratings and their
physical size and performance have been well known (Feinberg, 1979; CIGRÉ, 2001 and
McConnell, 2001).
Figure 4-1 presents a simplified cross sectional area of a basic three-leg core type
distribution transformer (including windings in one of the windows).
FIGURE A4-1 DISTRIBUTION TRANSFORMER –BASIC DIMENSIONS
Rating
The rating per phase of the transformer S (MVA), could be expressed as a function of
frequency f (Hz), flux density Bm (T), the cross sectional area of the magnetic core AFe (m2),
number of turns N1 and current I1 (A) in winding “1”.
Appendices
S = 4.44 fBm AFe N 1 I 1 [4-1]
Alternatively, the rating could be expressed as:
S = 2.22 fBm AFe ACon [4-2]
assuming that the current density is the same in both windings and that ACon is the overall
cross sectional area of both windings (m2), or
S = 1.11 fBm gA Fe kw Aw [4-3]
where g is the current density (A/mm2) in both windings, Aw is the core window area (m2)
and kw is window space factor (e.g. 0.3-0.4 for 11 kV transformers). It should be noted that
for constant MVA rating, flux density and current density, the product of conductor cross
sectional area ACon and core cross-sectional AFe is constant.
Equation [4-2] could be rewritten as:
S2 2.22 fB m gACon A Fe A Fe
A Fe = = S = S [4-4]
(2.22 fBm gACon ) (2.22 fBm gACon ) 2
2.22 fB m gACon
or
A Fe = K AS S [4-5]
Factor KAS is defined as the “output coefficient” for distribution transformers and it is
constant over a relatively wide MVA rating range. For three phase oil immersed
distribution transformers KAS is in the range of 0.04 – 0.05 (a nominal median value is
0.044). From Equations [4-1] and [4-5], it is also possible to express the volt/turn ratio
V/N as:
V
= 4.44 fB m A Fe = (4.44 fBm )2 K AS 2 S [4-6]
N
or
V
= K VS S [4-7]
N
where KVS , the “winding coefficient, is also constant for a wide range of MVA ratings.
Appendices
These two coefficients, the output coefficient and the winding coefficient are related as
follows:
K VS = 4.44 fBm K AS [4-8]
The typical design values for three phase distribution transformers used in the above
Equations are presented in Table 4-1.
Table A4-1 Typical Design Values for Three Phase Oil-Immersed Distribution Transformers
Design Parameter Range Typical Value
Flux – B (T) 1.55 – 1.80 1.72
Current Density – g (A/mm2) 1.5 – 3.0 2.4
AFe/ACon 1.4 – 2.8 1.6
KAS 0.04 – 0.05 0.044
KVS 14 – 20 17
Equations [4-5] and [4-7] are used in scaling performances of distribution transformers.
The mean turn length s is a function of AFe0.5 and bw/4, where bw is the width of the core
window (Fig. 4-1). Consequently, s is a function of S 0.25 :
(
s → A Fe 0.5 + b w / 4 → S 0.25 ) [4-9]
As an example for scaling factors, the load losses could be expressed as:
S 2R K S 2 N 2s S 2 S 0.25
PLL = = 1 2
= K 2 0.5
= K 3 S 0.75 [4-10]
1000V AConV SS
The other scaling factors could be derived in a similar way. Some of them are graphically
presented in Figure 4-2. Table 4-2 presents comparison of theoretical values and calculated
scaling factors for three-phase oil immersed distribution transformers developed for
Australian market.
Appendices
Scaling Factors for Distribution Transformers

2.5
Cost, Weight,
Total Losses:
2.0
3/4 power
Scaling Factors
1.5 Linear
Dimensions:
1.0 1/4 power
% Losses,
0.5
% Resistance:
-1/4 power
0.0
0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5
kVA Rating Ratio
FIGURE A4-2 SOME COMMON SCALING FACTORS FOR DISTRIBUTION TRANSFORMERS
Table A4-2 Scaling Factors for Category 3 Pad-mounted Distribution Transformers (1,250
kVA-2,000 kVA)
Quantity Theoretical Scaling Factor Calculated Scaling Factor
Weight (kVA rating ratio) 0.75 (kVA rating ratio) 0.62-0.72

Cost (kVA rating ratio) 0.75 (kVA rating ratio) 0.51-0.63
Length (kVA rating ratio) 0.25
Width (kVA rating ratio) 0.25
Height (kVA rating ratio) 0.25
Total Losses (kVA rating ratio) 0.75 (kVA rating ratio) 0.65-0.75
No-load losses (kVA rating ratio) 0.75
Exciting Current (kVA rating ratio) 0.75
% Total loss (kVA rating ratio) -0.25
% No-load loss (kVA rating ratio) -0.25
% Exciting Current (kVA rating ratio) -0.25
% Resistance (kVA rating ratio) -0.25
% Reactance (kVA rating ratio) 0.25
Volts/turn (kVA rating ratio) 0.5
Appendices
APPENDIX 5 - ASSESSMENT OF AEEMA/ESAA LOSS EVALUATION

FACTORS
The loss evaluation factors for distribution transformers defined in the non-binding
industry standard Specification for Polemounting Distribution Transformers
AEEMA/ESAA (1998) are as follows GWA (2002):
• distribution transformers below 100 kVA, KNLL=$6.30/W and KLL=$0.70/W;
• distribution transformers 100 kVA and above, KNLL=$6.30/W and KLL=$1.80/W;
Table A5-1 Calculation of Net Present Value of Transformer Losses based on AEEMA/ESAA,
(1998) – GWA (2002)
1,500 kVA Low 1,500 kVA High
Item Unit
Efficiency Efficiency
Rating kVA 1,500 1,500
Full load (power factor = 1) kW 1,500 1,500
Core loss kW 4.5 3.0
Winding loss @ 50% load kW 4.5 3.0
Efficiency at 50% load - 98.8% 99.2%
No load loss factor $/W 6.30 6.30
NPV of no load energy lost $ 28,350 18,900
Load loss factor $/W 1.80 1.80
NPV of load loss $ 36,450 24,300
Purchase price $/kVA 40 40
Purchase price $ 60,000 60,000
Total capitalised cost $ 96,450 84,300
NPV of loss/total cost - 37.8% 28.8%
Lifetime years 30 30
Annual throughput @ 50% load kWh 6,570,000 6,570,000
Annual loss @ 50% load kWh 78,840 52,560
Implied costs of losses, 50% load $/kWh 0.049 0.049
Implied costs of losses, 20% load $/kWh 0.055 0.055
Appendices
From AEEMA/ESAA evaluation factors it is possible to estimate the value which

distributors who adopt that specification place on energy losses in distribution
transformers. Table A5-1 gives an example using typical data for two 1,500 kVA
transformers of different efficiency levels.
The Net Present Value (NPV) of the energy lost, at a discount rate of 10%, has been
calculated by assuming that the annual energy losses at 50% loadings would be constant
for the 30 years of transformers’ operating life. Under these assumptions, the value of
losses implied by the ESAA/AEEMA formula is 4.9 c/kWh for transformers operating at
50% load and 5.5 c/kWh at 20% load. The implied value of lost energy is the same
irrespective of the efficiency of the transformer. However, as the total capitalised cost for
more efficient transformer is $12,150 lower, it would be prudent to purchase this more
efficient transformer. Typically, the NPV of the capitalised losses is in order of one a third
of the initial cost of the transformer, so the use of the formula assigns significant value to
energy efficiency in the selection process.
However, as GWA (2002) pointed out “the value of energy loss appears to be too low,
given that the average sale price of electricity (which a distributor-retailer would gain in full
as cost-free revenue is about 8.8 c/kWh. The AEEMA/ESAA specification is advisory
only, and there are indications that its use is declining as distributors (who are no longer
distributor-retailers) respond to the new regulatory and commercial climate: for
distribution-only organisations, the appropriate value of losses is the marginal cost of
supplying an additional kWh to the network, rather than the revenue to be gained from
selling a kWh to end users. For efficient capital investment to take place, the value assigned
to losses needs to be a long range projection of the cost of generation, effectively the Long
Run Marginal Cost (LRMC) of additional generation. In pre-electricity market days the
Bulk Supply Tariff was based upon LRMC projections of Generation and Transmission
costs and it was simply used by distributors as part of their investment analysis. What is
now required is a broadly equivalent long run estimate of electricity pool prices at the
market regional reference node. Each distributor should use the same value, with
adjustment made by the distributor for the cost of transmission and distribution to the
point of loss consumption” IPART (1999).
Appendices
Electrical utilities should assign a value to distribution transformer energy losses, which is
equal to the value of the revenue from selling that energy to the customer. In addition,
there should be additional component related to the value of the postponement of the
capital cost of distribution network augmentation. This additional component is highly
variable (as described in Chapter 5).

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Chapter Six: Introduction of Mandatory MEPS for Distribution Transformers in Australia

6. INTRODUCTION OF MANDATORY MEPS FOR DISTRIBUTION

6.1.1. Regulatory Framework for MEPS

Energy consumed by various equipment and appliances is a major source of greenhouse

attributable to equipment and appliances is application of Codes and performance

Minimum Energy Performance Standards (MEPS) is a government regulatory program

Equipment Energy Efficiency Committee (NAEEEC) is a regulatory body that includes

provision of relevant information for consideration by the ANZMEC. ANZMEC has

commercial equipment identified as a significant contributor to the growth in energy

equipment” (NAEEP, 2001a). The MEPS development process includes feasibility

assessment (technical, economic cost-benefit analyses and available supervisory measures)

and wide public consultations before any final decision is made.

6.1.2. Why Are Distribution Transformers Being Considered For MEPS

almost all power generated in Australia passes through distribution transformers

means even small improvements in transformer efficiency can result in

significant savings of energy and in greenhouse gases reduction;

average of 25 years to as much as 50 years for lightly loaded distribution

transformers are not motivated to invest in more efficient distribution

• there is no market incentive for private purchasers of distribution transformers

(around 15% of the market) to purchase efficient distribution transformers as

they easily include increased energy cost of inefficient distribution transformers

their products and services);

• “cumulative savings by 2015 resulting from the introduction of MEPS in 2005

are estimated to be at least 346,000 tons of carbon dioxide equivalent (CO2-e)

and could be as high as 950,000 tons CO2-e” NAEEP (2001a).

6.1.3. The Original MEPS Program

In 1994 NAEEEC commenced investigations about potential benefits of mandating

MEPS for distribution transformers. In 2000 a Steering Group including representatives

transformers from 15 - 2,500 kVA. The NAEEEC developed a multi-staged public

consultation process aiming to introduce nationally consistent standards for distribution

distribution transformers by:

(CAN/CSA-C802.1 and CAN/CSA-C802.2, 2001);

• exploring stakeholder support for developing higher energy performance standards

for products to be marketed as “high efficiency” distribution transformers,

possibly at a level that matches US standards for distribution transformers, which

were to come into force by July 2003;

• helping stakeholders to promote high efficiency products to the Australian

6.2. Development of MEPS Methodology for Australian Distribution

Development of MEPS for distribution transformers requires appropriate test procedures

develop MEPS methodology and to establish appropriate MEPS levels:

• the statistical approach;

• the engineering approach.

The statistical approach is focused on a specific market at a specific time. It includes

of models available at a specific time in a particular market” GWA (2002).

The engineering analysis approach involves selection of a representative model. Such a

“baseline” model normally incorporates the characteristics and technological features

typical of a group of products under investigation. Alternative design options and

effects of changing those relationships. In the statistical approach the existing

relationships are considered to hold;

capacity to produce complying models within a specified time, without

unacceptable adjustment costs (which are separately analysed);

of the market in question”.

It should be noted, however, that this engineering method is time-consuming, resource-

manufacturers and/or detailed knowledge of design and manufacturing principles).

Development of Australian MEPS levels for distribution transformers is based on global

Australian strategy for development of MEPS, which is endorsed by ANZMEC in 1999.

engineering and/or statistical approaches). This strategy is outlined in “National Appliance

and Equipment Energy Efficiency Program: Future Directions 2002-04” NAEEEP