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Safe and secure power distribution

Arc fault protection solutions
2 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

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The Noble Art of Switchgear
Arc Fault Protection

—
Power system operation fault statistics reveal
that a vast majority of the switchgear arc faults
are caused by incorrect human actions or by
aging network equipment. One way of reducing
human-related or equipment-associated fault
risks is to focus investments on technological
solutions that enhance the operating
environment.

The basic necessity of a switchgear arc fault

protection system can be investigated from the
probability aspect of arcing faults or from the
aspect of their adverse effects. The perspective
of investigation usually focuses on staff safety
and security and on asset management. Both
sectors are of essential business importance for
network companies as well as industrial
enterprises.
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4 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

Impacts of power system arc faults Equipment fault proneness a function of time
Electric arcs may cause instant and severe burns As the life-time of electrical devices extends over
to persons happening to stay close to the fault, decades, changes constantly occur in their
when it arises. Typically, this is the case if the operational proximity and the customer base
arc incident is caused by an incorrect switchgear they serve. The legislation and regulations may
operation. The arc flash easily causes a fire, also change over the operational life-time of the
which, in addition to the immediate damage, also equipment. For instance, a switchgear system,
creates fire gases and consequential damage which originally was intended for limited supply
due to smoke and stain. The fire gases of burning of power to a small population centre, may later
electrical devices are particularly dangerous for have to supply power to a shopping mall serving
people residing in the same area. thousands of customers seven days a week.
The role of the switchgear system may also have
The effective life-time of distribution network become more critical. Possible power outages
equipment is typically in the range of decades. may cause considerable economic losses to
Network companies and industrial enterprises the customers.
aim at maximizing the operational life-time of
their equipment and to reach the financial goals. Furthermore, the loading of the switchgear
has grown and for this reason a second power
transformer has been installed in parallel with the
first one. In peak load situations the transformers
can be run in parallel, which also causes the short
circuit power to increase. At the same time the
arc fault energy and the resulting damage in
case of an arc fault increase.
 5

Changing working manners pose risks work staff. The fact that when the current
In power systems the maintenance need of the maintenance people of the network companies
primary system equipment is generally small. reach the age of retirement, the familiarity of the
Therefore the equipment maintenance intervals new staff with the network systems decreases on
tend to be fairly long. There is also just a limited a local level. In addition, the need of the network
need to perform local control of such components companies to outsource maintenance functions
as breakers and switches. Under these further add to the risks of human errors.
circumstances the personnel will not obtain the
necessary experience to work with power system Over the years the working conditions of the
components. The personnel’s lack of experience devices degrade. The aging and degeneration of
will pose an increased risk of making mistakes protective structures and auxiliary furnishing
during maintenance work and fault clearance expose the equipment to dust, moisture,
activities. The probability of accidental arc faults temperature variations and rodents. The
is also increased by changes in the utility’s condition of the switchgear system is also
affected by stress factors and excessive loading,
which may cause untightening of joints and
degeneration of bushings.

By investing in protective equipment such as

arc fault protection, the safety and security
of the switchgear system can be enhanced.
The investment done in protection equipment
will also extend the life-time of the switchgear
installation, postponing possible investments
in new switchgear or even substations to a
later date.
6 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

—
Milliseconds that count
Time is a critical parameter in reducing the effects of arc faults, as the arc incident
energy rapidly increases by time. An arc fault lasting for 500 ms may cause severe
damage to the installation. If the arc flashes for less than 100 ms the damage is often
limited, and if the arc is extinguished in less than, say 4 ms the damage will be
insignificant.

Operating time By installing an arc fault protection system

The operating time of the protection is the the operating time can be halved. This means
prime factor with regard to the elimination of the that the switchgear damage is reduced to a
adverse effects of arc faults, seen not only from tolerable level, typically limited to a single
the point of view of staff safety and security, switchgear cubicle. A total operating time of
but also from the switchgear and environmental a couple of milliseconds can be reached by using
point of view. When the selectivity of the a separate arc flash eliminator for earthing
protection system is based on time grading, the busbar. This procedure causes the electric
the protection operating time at switchgear arc to die out immediately at the moment of
faults is typically hundreds of milliseconds. earthing. Due to the ultra-fast earthing function
With a separate busbar protection system a total no significant pressure increase will develop
operating time of about 100 milliseconds can in the switchgear system and no significant
be achieved, much depending on the speed of damage will arise.
the circuit breaker.

—
Arc fault damage as a function of the arc fault energy and the arc fault impact time.

Arc fault energy [kA 2s]

300 Steel fire

Copper fire
200

Cable fire

100 200 Fault impact time [ms]

 7

Selectivity also capable of detecting arcing faults between

In conventional arc fault protection solutions the phase conductors and the switchgear frame.
electrical faults in the cable terminations of Even in phase-to-frame faults the operating time
outgoing feeders are typically handled by the of the arc fault protection system is as short as
busbar protection system, although these faults for inter-phase arc faults.
could be eliminated using the circuit breaker
of the faulted outgoing feeder. Modern arc fault Redundancy
protection systems are not restricted by lack of A reliable function of the protection system is
selectivity. When an arc fault protection system of crucial importance for critical network nodes.
is used the interruption caused by a cable These cases justify the implementation of a
termination fault affects only the consumer redundant protection system, fully independent
loads supplied by the faulted cable feeder. of the basic protection system. An autonomous
In cable termination faults the whole substation arc fault protection system perfectly fulfils this
will normally be blacked out resulting in a requirement, as its function is based on a
much more widespread interruption of the different physical phenomenon than conventional
power supply. protection solutions and on a dedicated
technology.
An earth-fault rapidly tends to develop into
an arcing fault, because the operating time of
the basic earth-fault protection system is usually
relatively long. Arc fault protection systems are
8 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

—
An ABB solution for any application
ABB’s arc fault protection systems provide appropriate solutions for
both green field projects and retrofit installations.

—
Switchgear
The arc fault protection
introduction tool renewal
High

presents a product
portfolio diagram REA+
mapping alternative
UFES
Moderate Significant

strategies and
Arc fault probability

solutions.
REA
615 and 620 series
with integrated arc fault protection
Low

Maintenence
work
Minor Moderate Significant Serious
Impact of arc faults

From the comprehensive and compatible the rest of the proximity. Furthermore, industrial
arc fault protection system assortment the customers may suffer great losses of production
customers can choose their solutions according due to arc faults.
to their own preferences. An already existing
main protection scheme can be completed with The volume and type of investments needed
an independent arc fault protection system or to enhance the safety and security of the
it can be upgraded by using protection relays power system, and the reliability of the power
with integrated arc fault protection in the basic distribution can be studied by performing
functionality set-up. The ABB arc fault protection risk analyses.
systems provide detection and isolation of
arcing faults starting from either earth faults In the process of choosing an arc fault protection
or from short circuits. solution for an existing switchgear system, its
expected remaining life-time is of significant
The selection of the appropriate arc fault importance. There are two alternative strategies
protection system preferably starts with a risk to choose from. Either the operational life-time of
mapping, which, on one hand, focuses on the the switchgear system can be prolonged by
probability of the development of an arc fault, additional investments, or the whole switchgear
and on the other hand, on the effects of a system can be renewed.
possible arc fault.
In modern switchgear systems the probability of
The probability of the development of arc faults damage due to arc faults is comparatively low.
is especially related to human factors but also Despite of that, it can, of technical and assembly
to the structure and the state of the switchgear reasons, be recommendable to provide the
system, the physical stress imposed on the switchgear panel with a system-wide supervision
system and the environmental stress on the solution serving for the whole operational
system. life-cycle of the switchgear system.

In the evaluation of the consequences of arc Please contact your local ABB product or
faults the implications on the staff safety and service sales in order to perform a risk mapping
security must be studied, as also the impacts for an arc incidence in your power system
on the power distribution, the buildings and installation.
 9

The 615 and 620 series protection relays

with integrated arc fault protection are adapted to
switchgear systems, which are important for the
distribution network and its customers. In these systems
the consequences of arc faults can be considerable to
the personnel and the surrounding, although the probability
of an arc fault is low. Due to the integration of arc fault
protection into the basic protection set-up the 615 series
relays present a universal solution. The operating time
including detection and submission of a trip signal from
the 615 series protection relays is typically 7–10 ms.
The operating time of the circuit breaker (30–60 ms)
will additionally delay the arc fault extinguishing.

The REA arc fault protection system

suits switchgear systems, where the damage to the
proximity has been limited by means of constructional
measures, but which are highly critical from the point
of view of the distribution network and the customers.
Switchgear systems having already served their time are
examples of installations, in which REA arc fault protection
easily can be installed afterwards. The REA arc fault
protection system is also a perfect match for replenishing
the protection system of double busbar switchgear
systems. The operating time including fault detection
and submission of a trip signal from the REA arc fault
protection system is <2.5 ms. The operating time of
the circuit breaker (30– 60 ms) will additionally delay
the arc fault extinguishing.

UFES (Ultra-Fast Earthing Switch)

is suited for switchgear systems, where staff safety and
security, and switchgear arc fault and fire damage are
crucial. Switchgear systems of shopping malls, buildings,
mining industry, off-shore applications and other limited-
size switchgear systems are typical examples of this
category. The fault detection and elimination time of an
UFES arc fault elimination solution is typically <4 ms.

REA and UFES as an integrated solution

meets switchgear systems, where staff safety and
security is of great significance and the switchgear system
is of utmost importance for the distribution network
and its customers. Switchgear systems of this type are
usually feeding hospitals, traffic nodes and process industry
facilities. The typical operating time of the REA and
UFES solution for detecting and eliminating an arc fault
is <4 ms.
10 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S
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Our references speak for themselves

—
Over the past decade thousands of ABB arc fault
protection systems have been delivered to over
40 countries worldwide. Systems have been
installed in distribution systems of power utilities
and heavy industry production facilities, such as
paper, steel, petrochemical and chemical
industry plants.

Arc fault protection systems have also been

integrated in the power distribution systems of
airports and harbours and in power distribution
systems of commercial and society service
facilities like shopping centres, water works and
sewage treatment plants, also including marine
and off-shore installations.
12 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

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Helsinki International Airport, Finland

Aviaenergia Oy supplies secured power to the airport was equipped with ABB arc fault
critical functions of the Helsinki Airport, including protection of the REA product line. Due to the
air traffic control and surveillance functions. location of the substation at the Helsinki airport,
In line with the company’s strategic decision safety and security measures and possible
also the recently erected new 20 kV substation outages caused by faults must be seen as part
supplying power to the top ranking Helsinki of the stringent airport safety program.
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Detmarovice Power Plant, Czech Republic

The Detmarovice Power Plant was built 1972 REA system obviously saved the lives of two
through 1976, and with its capacity of 800 MW it workers and minimized damage to mere smoke
is the largest coal-fired power plant in Moravia. and dust detriment. The estimated repair costs
In a modernization project the power plant would have mounted to approx. $1.6 million USD,
had been equipped with ABB’s modern REA arc had the plant not been provided with arc fault
fault protection. At an accident in 2002 the protection.
14 S A F E A N D S E C U R E P O W E R D I S T R I B U T I O N A R C FA U LT P R OT E C T I O N S O LU T I O N S

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Hanover Waterworks, Stadtwerke Hannover AG, Germany

Hanover’s municipal utility supplies energy, water modern switchgear system including IEC 61850
and other services to the citizens. The utility compliant REF615 feeder protection and control
operates three waterworks providing drinking devices with integrated arc fault protection.
water to a total of 650,000 inhabitants in the Arc fault protection was a necessity, because,
metropolitan area of Hanover. The 50 years old according to the requirement, the switchgear
switchgear system of the second largest Fuhrberg system had to be re-energized within half an hour
waterworks has recently been replaced by a after a fault-related power outage.

—
Wacker Chemie AG, Germany

Staff safety and security is of number one ABB provided an innovative retrofit solution
priority to Wacker Chemie AG and its chemical based on a new technology for arc elimination,
plants. In this context Wacker Chemie also needs the Ultra Fast Earthing Switch (UFES). The UFES
to minimize the arc fault hazards in connection system provides greatly enhanced staff safety
with medium voltage switchgear systems. and security during arc faults and radically
Wacker Chemie therefore needed a solution minimizes arc-fault related damage.
for minimizing the effects of such hazards.
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Pellesmäki substation, Savon Voima Verkko Oy, Finland

Staff safety and security have always been duty to assure staff safety and security, and to
put in focus at Savon Voima Verkko. Already in maintain power supply even in fault situations.
the 1990’s the power utility took a decision that Besides improving constructions, instructions
all new substations would be equipped with and guidance it is important that risks caused by
arc fault protection. The utility has also carried human error also are considered in the protection
outupgrading projects concerning existing system of substations. As outsourcing is used
substations, in which ABB’s REA arc fault to an increasing extent in substation work
protection systems were installed. As a network today, the risks related to human errors are
operator Savon Voima Verkko sees as its accentuated.

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Yale University Medical Campus, USA

The most important aspect of any electrical experienced a bus fault resulting in an arc flash
system is to have the best protection available to event. REA successfully detected the fault and
the personnel working with and on these cleared it before the traditional bus differential
systems. A recent installation that utilizes ABB’s protection (87 function) could detect the fault
REA Arc Flash Protection System at the Yale and pickup. The quick response time of REA
University Medical Campus for both bus resulted in no injuries to nearby personnel and
protection and arc flash hazard reduction minimal damage to the switchgear.
—
ABB Distribution Solutions
P.O. Box 699
FI-65101 VAASA, Finland
Phone: +358 10 22 11
Fax: +358 10 22 41094

—
ABB India Limited, Distribution Automation
Maneja Works
Vadodara – 390013, India
Phone: +91 265 272 4402
Fax: +91 265 263 8922

—
ABB AG
Oberhausener Strasse 33
DE-40472 Ratingen, Germany

abb.com/mediumvoltage
abb.com/substationautomation

Additional information
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1MRS756596 REV C EN 11-2018

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