May 2022 Various Transformers SPOC Final

BIDDING DOCUMENT FOR THE PROCUREMENT OF VARIOUS TRANSFORMERS.
RURAL ELECTRIFICATION FUND
BIDDING DOCUMENT
for the
Supply and delivery of various transformers
Tender Closing Date: 10 June 2022 , Time:1000hrs
Tender Number: REF/Inter/05/05/2022
Date of tender advert: 12 March 2022
Page 1 of 52
RURAL ELECTRIFICATION FUND
DECLARATION BY THE ACCOUNTING OFFICER IN TERMS OF SECTION 19(2)(C) OF THE

PUBLIC PROCUREMENT AND DISPOSAL OF PUBLIC ASSETS REGULATIONS,2018.
TENDER NUMBER: REF/INTER/05/05/2022
TENDER DESCRIPTION-SUPPLY AND DELIVERY OF VARIOUS TRANSFOTRMERS
DECLARATION
The procurement for the tendered goods/items is based on neutral and fair
technical requirements and bidder qualifications.
Signed
.............................
J.V MASHAMBA
CHIEF EXECUTIVE OFFICER
Table of Contents
Page 2 of 52
Part 1: Bidding Procedures
Part 2: Statement of Requirements
Part 3: Contract
Page 3 of 52
BIDDING DOCUMENT FOR THE PROCUREMENT OF VARIOUS
TRANSFORMERS.
PART 3 CONTRACT
PART 1: BIDDING PROCEDURES

References:
References to the Act are to the Public Procurement and Disposal of Public Assets Act
[Chapter22:23] and references to the Regulations are to the Public Procurement and Disposal
of Public Assets (General) Regulations (Statutory Instrument No. 5 of 2018). The terms and
requirements in the Act and Regulations govern the submission of Bids and should be read by
all Bidders. The evaluation of this tender shall be guided by requirements of the Act.
Table of tender requirements
11 kV SUBSTATIONS (number) 33 kV SUBSTATIONS (number)
Descripti 10kV 10kV 25kV 50kV 100kV 200kV 15kVA 25kV 50kVA 100kV
on A A 0.4 A A A A 33/0.4 A 33/0.4 A
0.23 11/0. 11/0. 11/0.4 11/0.4 33/0. 33/0.4
4 4 4
QTY 5 10 20 15 5 4 5 15 10 4
Lot No 1 2 3 4 5 6 7 8 9 10
Preparation of Bids
You are requested to bid for the supply of the goods specified in the Statement of
Requirements below, by completing and returning the following documentation:
1. the Bid Submission Sheet in this Part;
2. the Statement of Requirements in Part 2;
3. a copy of every document necessary to demonstrate eligibility in terms of section 28 (1)
of the Regulations;
4. Supplier Registration number showing that you are registered with the Procurement
Regulatory Authority of Zimbabwe(PRAZ);
5. A bid security or bid securing declaration in the format specified in this Part;
6. A copy of:
 Company profile
 Certificate of incorporation/proof of company registration in the country of origin
 Tax clearance certificate/proof of tax compliance
 CR 14(Proof of company ownership)
 ISO certificate for the manufacturer
 Letter of agency from the manufacturer(for non-manufacturers)
 Two Reference letters
Page 4 of 52
TRANSFORMERS.
PART 3 CONTRACT
The tender is subject to review in terms of Section 54 of the Act,therefore bidders shall be
required to pay the following fees in terms of Part IV of S.I 219 of 2020:
 Equivalent of ZW$30,000.00 for local bidders and USD$400.00 for foreign bidders .
Bidders must attach proof of compliance on the bid documents without fail.
You are advised to carefully read the complete Bidding Document, as well as the General
Conditions of Contract which are available on the Authority’s website, before preparing your
Bid. Part 3: Contract is provided not for completion at this stage but to enable Bidders to
note the Contract terms they will enter into if their Bid is successful.
The standard forms in this document may be retyped for completion but the Bidder is
responsible for their accurate reproduction. All pages of the Bid should be clearly marked
with the Procurement Reference Number above and the Bidder’s name and any reference
number.
Lots and Packages

The tender is divided into lots. Bidders may bid for one or all the Lots
Number of bids allowed

No Bidder may submit more than one bid, either individually or as a joint venture partner in
another Bid, except as a subcontractor. Where the procurement is divided into lots and
packages, only one Bid can be submitted. A conflict of interest will be deemed to arise if bids
are received from more than one Bidder owned, directly or indirectly, by the same person.
Clarification
All queries regarding the tender shall be forwarded by the bidder in writing on duly signed
company letterhead and emailed on the following three(3) email addresses :
kchinembiri@rea.co.zw; tshumba@rea.co.zw and buyer1@rea.co.zw , not less than five(5)
working days from the closing date of the tender. Ensure the quiry is emailed to ALL the three
email addresses without fail. Clarifications/Responses pertaining to the queries received shall
uploaded on REF website address www.rea.co.zw on the notice board page. It shall be the
responsibility of bidders to continuously check the website for such clarifications/quiry responses.
If a prospective tenderer sends a query less than the stated days above, the query may not be
responded. Any neglect, delay or failure on the part of the Tenderer to obtain additional
information on the above or any other matters, which the tenderer considers necessary, shall not
relieve him/her from responsibility as a Tenderer. Only bidders facing challenges in receiving
responses to their quiries may call the Procurement Administrator on 0719 409 691.
Pre-bid meeting
No pre-bid meeting shall be held in this tender.
Validity of Bids
The minimum period for which the Bidder’s bid must remain valid is ninety (90) days from
the deadline for the submission of bids.
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TRANSFORMERS.
PART 3 CONTRACT
Submission of Bids
Bids must be submitted in writing in a sealed envelope to the address below, no later than the
date and time of the deadline below. It is the Bidder’s responsibility to ensure that they
receive a receipt confirming submission of their bid that has correct details of the Bidder and
the number of the Bid.
The Bidder must mark the envelope with the Bidder’s name and address and the
Procurement Reference Number.
Bidders must submit three bid documents. The bidder must clearly mark the original copy
“ORIGINAL.”.Two other copies must be clearly marked “COPY.” In the event of any
discrepancy between the original and the copies, the original will prevail.
Late bids will be rejected. The Procuring Entity reserves the right to extend the bid
submission deadline but will notify all potential bidders who have collected the bidding
documents of the amended bid submission deadline.
Submission address: Chief Executive Officer

Rural Electrification Fund
Megawatt House
44 Samora Machel Avenue
Harare
Means of
Tenders must be enclosed in sealed envelopes and endorsed on the
acceptance:
outside with the advertised tender number , the description and
closing date. The bids shall be dropped in the tender box located at
the above stated address by the closing date and time personally or
by post. Upon bid submission, bidders must obtain a bid submission
receipt as proof of bid acceptance. Bidders are free to witness the
opening of the tenders on the named closing date and time.
Bid opening
Bidders and their representatives may witness the opening of bids, which will take place at
the submission address immediately following the deadline.
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TRANSFORMERS.
PART 3 CONTRACT
Withdrawal, amendment or modification of Bids
A Bidder may withdraw, substitute, or modify its Bid after it has been submitted by sending a
written notice, duly signed by an authorized representative. However, no Bid may be
withdrawn, substituted, or modified in the interval between the deadline for submission of
Bids and the expiration of the period of Bid validity specified by the Bidder or any extension
of that period.
Bid Prices and Discounts
The prices and discounts quoted by the Bidder in the Bid Submission Form and in the Price
Schedules must conform to the requirements specified below.
Prices must be quoted as specified in the Price Schedule included in Part 2 Statement of
Requirements. In quoting prices, the Bidder is free to use transportation through carriers
registered in any eligible country and similarly may obtain insurance services from any
eligible country. Prices quoted must include the following costs and components:
(i) the price must be quoted DDP(2020) that is inclusive of freight costs,insurance
costs(risk),import duties and taxes till delivery.
Payment of tender fees

All foreign bidders are expected to pay for any fees or the bid bond in the currency of their
bids while local bidders shall pay in local currency only.
Bid Security
Every bidder is required to include bid security as follows:
Bid Bond/Security
The Bid bond for this tender shall be RTGS$300,000.00.00(local bidders) and payable using
the following options (S.I 5 of 2018 section 26).Please note that foreign bidders must provide
the bid bond of equivalent value in the currency of their bid.
Option 1
A certified bank cheque; or
Option 2
A bank guarantee; or
Option 3
A cash deposit to Procurement Regulatory Authority of Zimbabwe (PRAZ)
NB: If Option 3 is chosen please note that the Tenderer must pay a non-refundable
Bid Bond/Bid security establishment fee equivalent to ZW$40,000.00(local bidders) and
USD500.00 (Foreign bidders) to the Procurement Regulatory Authority of Zimbabwe in
line with S.I. 299 of 2021 PART V item 4.
Any bid not accompanied by a Bid Security or Bid Securing Declaration, where this is a
requirement of bidding, will be rejected by the Procuring Entity as non-responsive.
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TRANSFORMERS.
PART 3 CONTRACT
The Bid Security or Bid- Securing Declaration of a Joint Venture (JV) must be in the name of
the JV that submits the Bid. If the JV has not been legally constituted at the time of bidding,
the Bid Security or Bid-Securing Declaration must be in the names of all intended partners.
Contract Administration Fees
The winning bidder(s) shall be required to pay applicable contract administration fees to
PRAZ in terms of part VI of Statutory Instrument (S.I) 299 of 2021 before contract signature.
Bidders must study and understand the fees structure provided in S.I 299 of 2021.
Administration fees payable by bidders for bids subject to review (SPOC fees)
The tender is subject to review in terms of Section 54 of the Act,therefore bidders shall be
required to pay the following fees in terms of Part IV of S.I 299 of 2021:
 Equivalent of ZW$30,000.00 for local bidders and USD$400.00 for foreign bidders .
Bidders must attach proof of compliance on the bid documents without fail.
Evaluation of Bids
Bids will be evaluated using the following methodology:
1. Preliminary examination to confirm that all documents required have been provided, to
confirm the eligibility of Bidders in terms of section 28 (1) of the Regulations and to
confirm that the Bid is administratively compliant in terms of section 28 (2) of the
Regulations.
2. Technical evaluation to determine substantial responsiveness to the specifications in the
Statement of Requirements;
3. Financial evaluation and comparison to determine the evaluated price of bids and to
determine the lowest evaluated bid.
Bids shall be fully evaluated for all the stages and bids failing on any stage shall be rejected.
Review by the Special Procurement Oversight Committee

Section 54 of the Act provides for review by the Special Procurement Oversight Committee
for certain especially sensitive or especially valuable contracts. The tender is subject to review
therefore three identical copies of the bid document are required and that, where the copies
are not identical, the contents of the bid marked original will alone be considered.
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TRANSFORMERS.
PART 3 CONTRACT
Evaluation criteria
The Procuring Entity’s evaluation of a Bid will take into account, in addition to the Bid Price,
the following criteria and methodologies.
(a) Compliance to technical specifications-Bidders must fully comply with the technical
specifications provided in this tender. Since the tender requires bidders who hold
the transformers ex stock, compliant bidders must attach proof of quality
certification issued by Zesa Enterprises(ZENT).
(b) Price and pricing format-Bidders should submit their bid prices with the following
format. Failure to follow the format below may lead to disqualification of the bid:
Lot Description of Qty Unit Price Total Total Incl Unit Price
No transformer Excl VAT 14.5% VAT USD$ Excl VAT
USD$ VAT USD$ ZW$
B1 Transformers Xx
2 Transformers Xx
3 Transformers xx
4 Transformers xx
 Bidders are free to quote for one or more lots
IMPORTANT NOTES
• Dual pricing in terms of Statutory Instrument (S.I) 185 of 2020-Bidders
must quote their bid prices both in USD and the RTGS currency using the
prevailing exchange rate. Bidders must state the exchange rate used.
• Payment shall be strictly in local currency at the prevailing exchange rate
using the RBZ exchange rate(mid-rate). See http://www.rbz.co.zw/.
The prevailing RBZ exchange rate(mid-rate) on the date of tender closing
shall closing shall be used as the base rate where necessary.
• The bid price should clearly and separately show the unit price and the
total price.
• The USD prices shall be used for purposes of tender evaluation and tender
award.
• Bidders MUST state clearly whether they charge VAT or not.
(c) Should REF receive bids in different currencies , the currency of evaluation will be the
USD currency . Any bids in a different current currency shall be converted into USD
using the RBZ exchange rate (mid-rate) obtaining on 01 June 2022. See
http://www.rbz.co.zw/.
REF reserves the right to amend the tender quantity during evaluation in line with
budgetary provisions and or other considerations.
(d) Delivery schedule: Successful bidder(s) shall be required to deliver the transformers
five(5) days from the date of contract signing or from the date a purchase order is issued,
whichever comes first. The delivery address for the tender shall be:
 REF Central Stores No.22A James Martin Road, Lochinvar Harare Zimbabwe. REF
reserves the right to reject the right to reject any deliveries or products that do not
meet the technical specifications provided in this tender.
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TRANSFORMERS.
PART 3 CONTRACT
(e) Payment terms-Bidders must state the preferred payment terms
However REF shall pay the winning bidder whether it’s a local bidder or foreign bidder in
local currency(ZW$) only:
 Prepayment -REF favors payment after delivery, however where a bidder
require pre-delivery payment they must state ability to secure a bank guarantee from
a registered commercial bank acceptable to REF equal to the amount to be advanced.
The bank guarantee must be provided within two weeks of contract signing.
NOTE: Foreign bidders must provide a bank guarantee confirmed by any
local commercial banks or provide a bank guarantee issued by any local banks.
(f) Bidders must state whether the transformers are imported or are locally
manufactured without fail. State the country of origin without fail.
(g) Bidders should provide their local bank account details without fail.
(h) Delivery term shall be Delivered Duty Paid(DDP)(2020),Harare Central Stores-That is
Inclusive of freight costs, transit insurance (risk),all import duties and costs until
delivery at REF Central Stores No.22A James Martin Road, Lochinvar Harare
Zimbabwe.-Bidders MUST state that the delivery term shall be DDP(2020) Central
Stores No.22A James Martin Road, Lochinvar Harare Zimbabwe.
(i) The transformers shall be tested by Zesa Enterprises Engineers before they are received
by REF Central Stores at the supplier’s cost. REF reserves the right to reject goods that
do not meet the required tender specifications.
(j) Bidders must be registered with the Procurement Regulatory Authority of
Zimbabwe(PRAZ)- Bidders must attach proof of registration with PRAZ on the
list for supply of electricals/hardware. However foreign bidders shall only be required
to register with PRAZ if awarded the tender and before contract signature.
(k) Letter of agency-non-manufacturers must attach a letter of agency from the
manufacturer with the bid documents without fail.
(L) Product brochure- Bidders are required to attach a product brochure for the transformers
tendered without fail.
(m) Valid ISO certificate of the manufacturer of the transformers must be
Provided.The name of the manufacturer on the ZENT certificates or on the transformers
must tally with the name on the ISO certificate or the bid will be rejected)- Bidders must
attach proof without fail.
(n) Foreign bidders must clearly state in their bids that they have checked that the
transformers tendered “fall” or “do not fall” under the Consignment Based Conformity
Assessment (CBCA) programme as required by the Government of Zimbabwe. If the goods
tendered “fall” under the CBCA programme, bidders must further state that all costs
associated with this requirement will be to the supplier’s account. Bidders who hold the
transformers ex-stock do not need to comply with this requirement.
(o) Delivery period. The winning bidder(s) shall be required to deliver the transformers
within a period five(5) days the date of contract signing or the date a purchase order is
issued whichever comes first. Bidders must state their capacity to deliver within a
period of five(5) days as required.
(p) Reference letters-Bidders must attach at least two reference letters from
companies where the bidder has supplied transformers over the past two years. Reference
letters referring to supplies done more than two years old will not be acceptable.
(q) Bidders must state a warranty period of 12 months for the supplied items.
(r) Bid bond compliance-Bidders must attach proof of bid bod compliance as per
Part one of this bidding document without fail.
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TRANSFORMERS.
PART 3 CONTRACT
(s ) Compliance with Administration fees payable by bidders for bids subject to review
(SPOC fees)-Bidders must attach proof of payment for SPOC administration fees as per
part one of this bidding document.
(t) Bid validity of a minimum of 90 days is required and must be clearly stated.
(u) The Bidders must submit the bid with a duly filled in and signed Declaration
On Non-Engagement in Corrupt or Fraudulent Practices Form Annexure 2.
(v) The bidder must submit with the bid a duly filled in and signed attached Form
of Tender Annexure 3.
(w) Attach the bid submission form attached on page 13 of this document. Bids without the
bid submission form may be rejected.
Eligibility and Qualification Criteria

Bidders are required to meet the criteria in section 28 of the Act to be eligible to participate in
public procurement and to be qualified for the proposed contract. To be eligible, Bidders
must:
1. have the legal capacity to enter into a contract;
2. not be insolvent, in receivership, bankrupt or being wound up, not have had business
activities suspended and not be the subject of legal proceedings for any of these
circumstances;
3. not have a conflict of interest in relation to this procurement requirement;
4. not been debarred from participation in public procurement under section 72 (6) of the
Act and section 74(1) (c), (d) or (e) of the Regulations or declared ineligible under section
99 of the Act;
5. have the nationality of an eligible country as specified in the Special Conditions of
Contract; and
Participation in this bidding procedure is open to both Zimbabwean and foreign bidders.
Origin of Goods
All goods and related services must have as their country of origin an eligible country, as
specified in the Special Conditions of Contract.
Technical Criteria
The Technical Specifications Sheet details the minimum specification of the goods required.
The goods offered must meet this specification, but no credit will be given for exceeding the
specification.
Page 11 of 52
TRANSFORMERS.
PART 3 CONTRACT
Award of Tender Criteria

Tender shall be awarded to the lowest priced bidder to specification who hold the tendered
items ex-stock. Where the winning bidder holds less-than the tender quantity, REF may
award the tender for one lot to different bidders who hold the transformers ex-stock until the
tender quantity is fulfilled. Bidders who hold the transformers ex-stock must state that they
hold the goods ex stock without fail and the quantity held in stock.
Bidders who hold the transformers ex-stock MUST attach ZENT quality check certificates as
proof of ex stock status. Bids without ZENT certificates shall be treated as non-stock holders
during evaluation.
REF reserves the right to visit bidders premises and inspect the items stated as EX-STOCK
and findings by the visiting team shall be used for evaluation of this tender. NB: BIDDERS
WHO FALSELY CLAIM TO HOLD STOCK MAY BE DISQUALIFIED FROM THE
TENDER PROCESS. Bidders are allowed to quote for the full or part tender quantity.
Bidders who do not hold the transformers ex stock shall be disqualified as non-
compliant.
The proposed award of contract will be by issue of a Notification of Contract Award in terms
of section 55 of the Act which will be effective until signature of the contract documents in
accordance with Part 3: Contract. Unsuccessful Bidders will receive the Notification of
Contract Award and, if they consider they have suffered prejudice from the process, they may
within 14 days of receiving this Notification, submit to the Procuring Entity a Challenge in
terms of section 73 of the Act, subject to payment of the applicable fee set out in section 44
of and the Third Schedule to the Regulations.
Right to Reject
The Procuring Entity reserves the right to accept or reject any Bids or to cancel the
procurement process and reject all Bids at any time prior to contract award.
Corrupt Practices
The Government of Zimbabwe requires that Procuring Entities, as well as Bidders and
Contractors, observe the highest standard of ethics during the procurement and execution of
contracts. In pursuit of this policy:
1. the Procuring Entity will reject a recommendation for award if it determines that the
Bidder recommended for award has, directly or through an agent, engaged in corrupt,
fraudulent, collusive or coercive practices in competing for the Contract or been declared
ineligible to be awarded a procurement contract under section 99 of the Act;
2. the Authority may under section 72 (6) of the Act impose the sanctions under section 74
(1) of the Regulations; and any conflict of interest on the part of the Bidder must be
declared.
Page 12 of 52
TRANSFORMERS.
PART 3 CONTRACT
Bid Submission Sheet

{Note to Bidders: Complete this form with all the requested details and submit it as the first
page of your Bid. Attach the completed Statement of Requirements and any other documents
requested in Part 1. Ensure that your Bid is authorised in the signature block below. A
signature and authorisation on this form will confirm that the terms and conditions of this
Bid prevail over any attachments. If your Bid is not authorised, it may be rejected. If the
Bidder is a Joint Venture (JV), the Bid must be signed by an authorized representative of the
JV on behalf of the JV, and so as to be legally binding on all the members as evidenced by a
power of attorney signed by their legally authorized representatives.
Bidders must mark as “CONFIDENTIAL” information in their Bids which is confidential to
their business. This may include proprietary information, trade secrets or commercial or
financially sensitive information}.
Procurement Reference Number:

Subject of Procurement:
Name of Bidder:
Bidder’s Reference Number:
Date of Bid:
We offer to supply the items listed in the attached Statement of Requirements, at the prices
indicated on the attached Price Schedule and in accordance with the terms and conditions
stated in your Bidding Document referenced above.
We confirm that we meet the eligibility criteria specified in Part 1: Procedures of Bidding.
We declare that we are not debarred from bidding and that the documents we submit are true
and correct.
The validity period of our bid is: ……… {days} from the date of submission.
We confirm that the prices quoted in the attached Price Schedule are fixed and firm for the
duration of the validity period and will not be subject to revision, variation or adjustment.
Bid Authorised by:
Signature …………………………….. Name: ……………………………………
…………………….……(DD/MM
Position: Date:
…………………………….. /YY)
Authorised for and on behalf of:
Company ……………………………………………………………………………………
Address: ……………………………………………………………………………………
Page 13 of 52
TRANSFORMERS.
PART 3 CONTRACT
Technical Specification and Compliance Sheet
Name of Bidder:
Bidder’s Reference Number:

TECHNICAL SPECIFICATIONS FOR THE TRANSFORMERS
Instructions to bidders
Since the tender requires bidders who hold the transformers ex stock, compliant
bidders must attach proof of quality certification issued by Zesa Enterprises(ZENT).
The technical specifications below are provided for the information of bidders only.
Summary requirements
11 kV SUBSTATIONS (number) 33 kV SUBSTATIONS (number)
Descripti 10kV 10kV 25kV 50kV 100kV 200kV 15kVA 25kV 50kVA 100kVA
on A A 0.4 A A A A 33/0.4 A 33/0.4 33/0.4
0.23 11/0. 11/0. 11/0.4 11/0.4 33/0.
4 4 4
QTY 5 10 20 15 5 4 5 15 10 4
Lot No 1 2 3 4 5 6 7 8 9 10
Page 14 of 52
TRANSFORMERS.
PART 3 CONTRACT
REF SPECIFICATION NO. 18001

DISTRIBUTION TRANSFORMERS
1. SCOPE ....................................................................................................................... 17
2. DETERMINATION OF RESPONSIVENESS ......................................................... 17
3. PARTICULARS OF ELECTRICAL SYSTEM ....................................................... 18
4. PARTICULARS OF ENVIRONMENT .................................................................... 18
5. STANDARDS, UNITS AND LANGUAGE ............................................................. 19
6. DESIGN ..................................................................................................................... 20
6.1 General ....................................................................................................................... 20
6.2 Windings .................................................................................................................... 21
6.3 Cores .......................................................................................................................... 21
6.4 Tapping Switches ....................................................................................................... 22
6.5 Bushings ..................................................................................................................... 23
6.6 Tanks and Conservators ............................................................................................. 23
6.6.1 General ....................................................................................................................... 23
6.6.2 Tanks .......................................................................................................................... 24
6.6.3 Conservators .............................................................................................................. 24
6.7 Accessories and Fittings ............................................................................................ 25
Page 15 of 52
TRANSFORMERS.
PART 3 CONTRACT
7.0 INSULATING OIL.................................................................................................... 26
8.0 OVERLOADING CAPABILITY .............................................................................. 26
9.0 NOISE POLLUTION ................................................................................................ 26
10. TESTS ........................................................................................................................ 27
11. PACKING AND TRANSPORT ................................................................................ 27
12. DRAWINGS AND DIAGRAMS .............................................................................. 28
12.1 Drawings to be supplied with the Tender .................................................................. 28
12.2 Drawings to be supplied with the Contract ................................................................ 28
13. MAXIMUM DIMENSIONS AND WEIGHTS REQUIRED ................................... 29
14. EVALUATION OF LOSSES .................................................................................... 30
14.1 Guaranteed Output and Losses, Liquidated Damages ............................................... 30
14.2 Evaluation of Losses (TO BE STATED).................................................................. 30
15. DELIVERY PERIOD ................................................................................................ Error! Bookmark
16. TECHNICAL SCHEDULES ..................................................................................... 31
16.1 Preamble .................................................................................................................... 31
16.2 Definitions and Abbreviations ................................................................................... 34
Page 16 of 52
TRANSFORMERS.
PART 3 CONTRACT
1. SCOPE
This specification covers the manufacture, testing, supply and delivery of distribution
transformers and spares. All transformers shall be capable of being loaded continuously
at the full rating at ambient temperatures of 35 C, while exposed to direct tropical sun.
The Supplier shall state name, place and country of manufacture. The Supplier shall state
whether or not the transformers are produced under license, in which case licence
holders name shall be stated.
Tenders shall include a complete statement of compliance with this specification. For
every clause in this specification the Tenderer shall state compliance or non-compliance
and shall elaborate where appropriate.
Tenders shall use the words ‘comply’, ‘do not comply’ for this specification or in the
clauses of an informative nature, ‘noted’. Where the words ‘do not comply’ are used the
Tenderer shall state whether modifications could be made and whether modifications
would be undertaken. The cost implications of such modifications must be indicated in
the statement of compliance as well as the pricing schedules.
Spares as recommended by the supplier should be included in the scope of supply.
The manufacture of the transformers should commence after inspection of the prototype
by a REF representative. The supplier will meet all the costs associated with the
inspection of the prototype transformers.
2. DETERMINATION OF RESPONSIVENESS
Prior to the detailed evaluation of Tenders, the Authority will determine whether each
Tender is substantially responsive to the requirements of the Tender Document.
2.1 For the purpose of this clause, a substantially responsive Tender is one which will
conform to all the terms, conditions and specifications of the Tender Document without
material deviations or reservations. A material deviation or reservation is one which
affects in a substantial way the price, scope, quality completion timing or administration
of the works undertaken by the Tenderer under the Contract, or which limits in a
substantial way, inconsistent with the Tender Document, the Zimbabwe Electricity
Supply Authority’s rights or the Tenderer’s obligations under the Contract and the
rectification of which would affect unfairly the competitive position of other Tenders
who have presented substantially responsive Tenders at reasonable price.
2.2 A Tender Determined to be substantially non-responsive will be rejected by the

Authority and may not subsequently be made responsive by the Tenderer by correction
of the non-conformity.
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TRANSFORMERS.
PART 3 CONTRACT
2.3 The Zimbabwe Electricity Supply Authority may accept any non-material deviation or
reservation provided that the acceptance thereof does not prejudice or affect the relative
ranking order of any Tender in the evaluation of Tenders.
3. PARTICULARS OF ELECTRICAL SYSTEM
Unless otherwise specified in Schedule of Requirements, it must be assumed that the

system on which the equipment will operate is :
a) Three phase overhead-line construction and underground system. The

maximum earth fault factor on the network is 1.5.
b) Operated at 50 Hz, with approximately sinusoidal wave form.
c) The highest system voltage does not normally exceed the nominal system
voltage by more than 10%. The nominal system voltages are 33 kV and 11 kV.
d) The system frequency variation does not exceed plus or minus 2.5% from 50 Hz.
Designs should allow for these variations.
4. PARTICULARS OF ENVIRONMENT
The transformers shall be capable of operating under the following environmental

conditions.
a) Ambient temperatures:
(i) Maximum: 40 °C
(ii) Minimum: minus 10 °C
(iii) Maximum daily average: 35 °C
b) Altitude:
Maximum altitude of 1 500 metres above sea level. The design shall
allow for reduced cooling effect due to high altitude.
c) The transformers will be exposed to direct tropical sunlight.
d) Humidity:
Humidity of 13mg per cubic metre absolute and 65% relative before
storms with vapour pressure of 17mmHg.
e) Transformers will operate within the tropics and will be subjected to

sudden ambient air temperature changes of the order of 10 C per hour,
Page 18 of 52
TRANSFORMERS.
PART 3 CONTRACT
occurring at the onset of rain, but the barometric pressure at any given place does
not vary by more than approximately 10mm Mercury. Frequent and severe
lightning storms occur during summer months, with isoceraunic levels varying
between 50 and 100 thunderstorm days per annum.
It is the manufacturers responsibility to make himself familiar with any

other climatic and physical conditions pertaining in Zimbabwe and to allow for
all conditions in his designs.
Particular attention should be paid in the design of all equipment to ensure that
there is no possibility of damage to working parts or insulation through the
ingress of dust, insects or vermin.
All orifices and air vents should be covered by easily replaceable

weather resisting, fine mesh wire where practicable.
5. STANDARDS, UNITS AND LANGUAGE
Except where modified by the Authority's Specifications, IEC Recommendations (IEC

76) shall apply throughout or British Standards (BS) where they amplify the IEC 76.
In the case of conflict between the above stated Standards and this Specification, the
ruling of this Specification will prevail.
All tenders, correspondence, description upon drawings, illustrations or instructions shall

be in unambiguous English Language. SI Units of measurements shall be used
throughout.
All materials used in the manufacture of the transformers shall be new and of high
commercial quality.
The transformers shall be manufactured to high quality standards.
Type test certificates are to be submitted with the tender for each transformer rating and
voltage. Type tests are either to be witnessed by or carried out by an internationally
recognised Test Institute, e.g. KEEMA and others. A minimum requirement is that the
Test Institute is unbiased with no direct connection to any private industries and that the
institute is engaged in type tests on behalf of international clients.
The transformers shall be sourced from manufacturers who have ISO 9001 Certification.
Documentary evidence of the ISO 9001 Certification shall be provided with the bid.
Manufacturers who cannot submit such certification are liable to be rejected.
Page 19 of 52
TRANSFORMERS.
PART 3 CONTRACT
6. DESIGN
6.1 General
a) The Transformers shall be of the mineral oil immersed core type suitable
for outdoor use with ONAN cooling.
The transformers shall be capable of withstanding the maximum possible

short circuit current (Assuming an infinite busbar at the H.V) for a period of one
second.
b) All transformers shall have a guaranteed life span of at least 25 years

operating continuously under full rated power at an ambient temperature of 35
C on any tapping under the following conditions:
i) With the voltage of the untapped winding at normal,

without the need to derate the transformer at the extreme tap positions
and without oil temperature rise exceeding 55 C at the top of the
transformer. The winding temperature rise shall not exceed 60 C.
ii) With voltage applied up to 10% in excess of the rated

tapping voltages and without injurious overheating.
(c) Transformers shall be connected in accordance with BS 171: three phase

transformers to Vector Group reference Dynll.
(d) The L.V neutrals shall be brought out of the tank to a readily accessible terminal
and shall not be earthed inside the tank, unless otherwise specified in the enquiry.
(e) Transformers on a particular contract with similar kVA rating, voltage ratios and
connections shall be suitable for parallel operation on all relevant taps under
which conditions they should share the load in proportion to their ratings subject
to the tolerances on impedance laid down in IEC 76 or BS 171.
(f) If it is required to parallel any transformer with existing transformers then

full details of the existing transformers will be provided when tenders are
placed.
(g) Low impedance transformers are preferred, a maximum of 5% being

envisaged on any size with no plus tolerance.
(h) An oil gauge shall be provided for non-sealed transformers.
The following details shall apply to sealed designs:
Page 20 of 52
TRANSFORMERS.
PART 3 CONTRACT
i) Transformers sealed by welding are not acceptable, and
will be rejected by the Authority.
ii) Any holes or plugs used to facilitate vacuum/pressure

testing, leak testing or oil filling of the transformer shall finally be
sealed.
iii) The expansion space for the oil shall not be less than 25
percent of the volume of the oil at 20 degrees Celsius, for transformers
with conservators and transformers using the tank for expansion, and
shall be nitrogen filled. The transformer shall be sealed at atmospheric
pressure.
iv) Transformers using the expandable ribs for expansion

shall be totally filled with oil and sealed at atmospheric pressure.
v) Pressure valves, pressure/vacuum gauges and non-return

valves shall not be fitted.
vi) Drain plugs shall be fitted to transformer tanks up to and

including 315 kVA, whilst drain valves shall be fitted to transformer
tanks above 315 kVA
vii) Earth studs are required at both the H.V and L.V ends of transformer.
6.2 Windings
(a) Tappings shall be provided in the H.V windings, preferably in the electrical
centre of the windings, to permit variation of the number of H.V turns without
any variation in the kVA rating. The variations shall be effected by means of a
manually operated tapping switch to be provided in accordance with clause 6(4).
(b) All windings and terminations shall be fully insulated and those for
service above 1 000 volts shall be designed for impulse voltage tests.
Designs shall be such that electrical stresses are as uniform as possible

throughout the windings under impulse conditions.
(c) Windings shall be vacuum impregnated and insulating materials shall not
be liable to soften, shrink, become brittle, carbonise, deteriorate, or collapse in
any way during service.
(e) L.V windings of Aluminium sheet are not acceptable. Transformers with such windings
will be rejected.
6.3 Cores
Page 21 of 52
TRANSFORMERS.
PART 3 CONTRACT
(a) The magnetic circuit shall be earthed to the core clamping structure, at one point
only, and the core assembly to the tank cover. Where transformers are not sealed,
readily accessible removable bolted links shall be employed for the earthing
connections.
(b) The general construction of the cores, framework and the clamping
arrangements shall be robust and such that they will be capable of withstanding
completely any stresses which may occur due to handling, transport or service.
All cores and yokes shall be terminated and clamped by means of a suitable
framework. Suitable means shall be provided for lifting the cores from the tanks.
(c) It shall not be possible for the core to move relative to the tank during
handling or transport. Designs which contravene this requirement will be
rejected.
(d) Particular attention shall be paid to maintaining low core loss consistent
with sound design.
6.4 Tapping Switches
(a) Transformers shall be provided with approved off-circuit type tap

changing equipment. A fully insulated off circuit externally manually
operated ganged tapping switch shall be separately capable of withstanding the
specified impulse voltage when connected to the transformer windings.
(b) Clearly visible tap position indication shall be provided. The tapping
switch shall be operated by means of an external handle which can be positively
located and locked in each operating position.
The switch shall be mechanically robust and provided with a device

between the handle and the switch to permit operation without strain in the event
of imperfect alignment between switch and handle. The switch operating shaft
shall be fully insulated as between tank and switch and shall be provided with a
suitable oil and vacuum tight gland where it passes through the tank.
(c) The use of wood shall be avoided wherever possible and all the supports and
terminal boards shall be completely unaffected by hot oil and shall be non-
moisture absorbent.
(d) High grade insulating materials shall be used in the construction of

tapping switches which shall be designed with special attention to the elimination
of points where tracking is likely to occur.
(e) Tapping switches shall be mounted on supports made of suitable high

strength insulating material and shall be provided with self-aligning spring
loaded wiping contacts capable of maintaining good electrical contact without
the need for periodic maintenance.
Page 22 of 52
TRANSFORMERS.
PART 3 CONTRACT
All clearance between tapping switch contacts and leads shall be
indicated on drawings submitted at the time of tendering and such clearances
shall be sufficient to prevent tracking or flashover in the event of carbon or
sludge deposits forming on leakage paths.
(f) The tappings to be provided on the H.V winding shall be as follows:-

Minus 5%: Minus 2.5%: 0%(Normal): Plus 2.5%: Plus 5%
6.5 Bushings
(a) All line terminals and neutral connections where specified, shall be
brought out to porcelain outdoor type terminal bushings. The bushings shall be
the outdoor type.
(b) Arcing horns with equal double gaps shall be fitted on all transformer
bushings above 660 volt. The total gap length (for two gaps) shall be set at 60 to
70mm for 11kV and 140 to 150mm for 33kV nominal voltage.
(c) The bushings shall have minimum Creepage distances of 670mm and
250mm for nominal voltages of 33 and 11kV respectively.
6.6 Tanks and Conservators
6.6.1 General
i) Drain valves may be either screwed or flanged whilst conservator isolator

valves shall be flanged. Drain valves shall be complete with captive plugs which
shall be either of non-ferrous metal or galvanised.
ii) All internal steel surfaces or tanks and conservators shall be shot blasted
and cleaned, and a coat of protecting compound, unaffected by hot oil, should be
applied.
iii) All external surfaces and parts made of steel are to be thoroughly shot
blasted and cleaned, after which two coats of priming paint, preferably of zinc
chromate, one intermediate coat, and one coat of finishing paint are to be applied.
The colour of the finishing coat shall be medium Sea Grey, Colour No. 637 to BS
381C.
iv) Transformers on which the paints are found to flake off or deteriorate
within the guarantee period shall be suitably cleaned and repainted free of charge
by the supplier. Suppliers providing such transformers will not in the future be
given the opportunity to offer transformers to REF.
Page 23 of 52
TRANSFORMERS.
PART 3 CONTRACT
6.6.2 Tanks
i) Each transformer shall be housed in a tank of welded steel plate

construction suitably stiffened where necessary but with a flat base.
Wheels as rollers shall be provided for transformers rated above 500

kVA. Transformers rated equal to or less than 500 kVA shall not be provided
with wheels as rollers.
ii) The lifting lugs shall be suitable for lifting the transformer bodily by
means of a hoist or crane when it is completely assembled and ready for service.
iii) All transformers up to and including 315 kVA rating shall be provided
with four fixing lugs on the base drilled with 16mm holes for bolting to a
platform.
The fixing holes shall project beyond the ends of the tank and be placed
to provide the most practicable stable arrangement.
6.6.3 Conservators
i) Conservators, shall be dimensioned such that oil expansion may occur

over the working range of temperature from no load with the transformer cold
and at minus 10 degrees Celsius ambient air temperature to full load at plus
40 degrees Celsius ambient air temperature while the sump pipe remains covered
and the oil level is visible or indicated.
ii) Drain plugs shall preferably incorporate approved sampling facilities, and
shall be mounted at the lowest part of the conservator tank and so designed that
the sampling device can be readily cleared in the event of its being blocked by an
accumulation of sludge etc., without the necessity of having to dismantle the
device completely.
iii) Oil level gauges on conservator tanks shall be of the refracting plate glass
or other approved type, marked with the level at 20 degrees Celsius at no-load
and capable of indicating the level of oil over the specified working range.
iv) Where dehydrating breathers are specified they shall be of the Silica gel
type which give indication of moisture absorption by change in colour of the
charge.
An inspection window shall be provided and mounted in a position

convenient for inspection. The breather is to incorporate an oil seal to prevent
contact with the external air when breathing is not taking place. The breather is to
be fitted on the LV end of the transformer.
Page 24 of 52
TRANSFORMERS.
PART 3 CONTRACT
6.7 Accessories and Fittings
(a) All transformers shall be provided with accessories and fittings in

accordance with the tables below, unless otherwise specified in the enquiry:
In the following tables ‘Y’ means yes (To be provided)

‘N’ means no (Not to be provided)
ACCESSORIES AND FITTINGS

FOR
11/0.4 and 33/0.4 kVA DISTRIBUTION TRANSFORM ERS.
Transformer Nominal Ratings
11k V Primary Voltage 33k V Primary voltage
Upto but 100 k VA 500 k VA 500 k VA
excluding but and upto but and
TRANSFORMER TANK FITTINGS 100 k VA excluding above excluding above
Free Sealed 500 k VA 500 k VA
Breathing
1 Conservator N N Y Y Y Y
2 Drain valve with captive sealing plug Y N Y Y Y Y
3 Lifting lugs Y Y Y Y Y Y
4 Thermometer Pock et N N N Y N Y
5 Rating and Diagram plate Y Y Y Y Y Y
6 Hanger irons Y Y N N N N
7 Platform mounting lugs Y Y Y N Y N
8 Earthing Terminal Y Y Y Y Y Y
9 Lightning arrestor brack ets N N N Y N Y
10 Dial type thermometer N N N Y N Y
11 Jack ing pads N N (Required only when the mass of the complete
transformer is 1 000 k g or more.)
12 Plain breather Y N N N N
13 Oil gauge Y Y On Concervator
14 Mounting plate for Item 6 to be suitable N N N Y N Y
for mounting marshalling box Item 17)
15 Lashing down facilities Y Y Y Y Y Y
16 Marshalling box for Item 10 of Tank fitting
and Item 7 of Conservator fittings
Conservator fittings
1 Drain plugs N/A Y Y Y Y
2 Sampler N/A Y Y Y Y
3 Separate filling hole with caps N/A Y Y Y Y
4 Dehydrating breather N/A Above 100 k VA Y Y Y
5 Plain breather N/A 100 k VA N N N
6 Oil gauge N/A Y Y Y Y
7 Gas and oil actuated relay N/A N Y N Y
8 Conservator isolating valve N/A N Y N Y
(b) Rating and diagram plates shall be of engraved brass or other approved non-corroding
material and shall be placed on the L.V side of the transformer.
(c) Where a thermometer pocket is provided, it shall be of a thin walled metal mounted in
the tank cover. The pocket shall project 25mm outside of the tank and shall be threaded
along the whole projecting portion with a 19mm B.S.P. male thread, a screwed cap shall
Page 25 of 52
TRANSFORMERS.
PART 3 CONTRACT
be provided to cover the pocket when not in use. The pocket shall have internal
dimensions of not less than 19mm diameter and 115mm length.
(d) Hanger irons, where specified, shall be suitable for suspending the transformer from a
102mm x 51mm Mild Steel Channel cross-arm, bolted to the vertical legs of an 'H' pole.
A suitable stop shall be provided at the base of the tank to enable the transformer to be
suspended vertically, and rest against a similar 102 mm x 51mm Channel provided on the
'H' pole at a lower level for this purpose. The hanger irons shall be drilled for an M16
bolt to enable them to be bolted to the vertical web of the cross-arm and thereby prevent
any lateral movement of the transformer.
The hanger irons shall be mounted on the LV side of the transformer tank.
7.0 INSULATING OIL
The transformers shall be fitted with low viscosity mineral insulating oil which
complies in every respect with the provisions of BS 148.
8.0 OVERLOADING CAPABILITY
The transformer shall be capable of overload at 35 C ambient temperature without

reduction in the anticipated working life of the transformer, as shown in the curve below.
TRANSFORMER OVERLOAD CAPABILITY

150
145
140
135
Percentage Load
130
125 % load
120
115
110
105
100
2
4
6
8
10
12
14
16
18
20
22
24
Hours
The maximum load at other periods is assumed to be 70% of the transformer rating
for the above transformer overload capability curve.
9.0 NOISE POLLUTION
Page 26 of 52
TRANSFORMERS.
PART 3 CONTRACT
The maximum values for the noise levels of the various distribution transformers shall be
as given in the table below:
TRANSFORMER RATING kVA MAXIMUM POLLUTION dB(A)

Less than or equal to 50k VA 48
Between 50 and 315k VA 55
Above 1600 k VA 61
Transformers with Noise Pollution levels higher than that given above will be rejected
by the Authority.
10. TESTS
Electrical tests are to be carried out according to IEC 76. Routine covering test
certificates shall be submitted immediately after completion of tests in the factory, for
each and every identical group of transformers.
The following tests shall be carried out in addition to the routine tests:
(a) As a type test, a temperature rise test on each different rating of transformer.
(b) As a special test, an impulse voltage withstand test including chopped

waves on each different rating of transformer.
NOTE: If tests to (a) and (b) above have been carried out
satisfactorily on designs identical in all essential details, tests (a) and (b)
may be waived on the production of acceptable certified type test certificates.
11. PACKING AND TRANSPORT
Transformers shall be transported to destination with their tanks full of oil up to the
service level.
Bushings and any accessories or fittings likely to be damaged shall be protected

adequately against damage in transit.
Page 27 of 52
TRANSFORMERS.
PART 3 CONTRACT
12. DRAWINGS AND DIAGRAMS
12.1 Drawings to be supplied with the Tender
The following drawings shall be supplied with any tender.
(a) General arrangement drawing of each rating of transformer offered showing :
(i) All dimensions on height, width, depth, etc., minimum clearance (phase
to phase and phase to earth) on H.V. and L.V. bushings including
clearance H.V. to L.V.
(ii) Weights of oil, core/winding assembly and transformer fully erected.
(iii) Positions and identification in a separate legend of all fittings with type
numbers.
(iv) Size and position of all fixing holes.
(b) Detailed dimensioned drawings of tapping switch illustrating type of material,

clearances, between tapping points and to earth and method of operation.
(c) Detailed dimensioned drawings of bushings, silica gel or plain oil seal type
breather, and conservator.
NOTE: Where sealed transformers are offered, a cross arrangement

drawing shall be submitted with the tender showing, in particular, details
of the tank construction and internal tank finish and the depth of the
expansion space above the oil.
12.2 Drawings to be supplied with the Contract
(a) Latest issues of the drawing listed under Clause 12.1 shall be supplied under the
contract. If no modifications are applicable to the drawings supplied with the
tender, this shall be confirmed in writing under the contract and further drawings
need not be supplied.
(b) Rating and diagram plate shall include the following information:
I) Manufacturer
ii) Size in kVA
iii) Vector group
iv) Voltage rating
v) Year of manufacture
vi) Total weight
Page 28 of 52
TRANSFORMERS.
PART 3 CONTRACT
vii) Full load loss
viii) No load loss
ix) Volume of oil in litres
x) REF Tender number
xi) REF order number
xii) Percentage impedance
xiii) Voltage table at various tap positions
13. MAXIMUM DIMENSIONS AND WEIGHTS REQUIRED
The dimensions of the transformers are as shown on the drawings above.
The dimensions referred to above shall mean the following:
i) Maximum height shall be denoted by (h1)

ii) Maximum width shall be denoted by (a1)
iii) Maximum depth shall be denoted by (b)
The maximum dimensions in mm and weights in kg shall be as indicated in the table

below. Any transformer whose dimensions and weights exceed the stated values will be
rejected.
RATING RATIO HEIGHT (h1) DEPTH (b) WIDTH (a1) WEIGHT

kVA (kg)
10 single ph. 11/0.4 900 770 782 240
10 11/0.4 850 780 800 245
15 11/0.4 929 782 930 360
25 11/0.4 929 782 930 360
50 11/0.4 1500 910 950 445
100 11/0.4 1650 1130 1050 673
15 33/0.4 1415 670 1500 500
25 33/0.4 1415 670 1500 550
50 33/0.4 2025 1230 1280 1180
100 33/0.4 2070 1490 1380 1250
Page 29 of 52
TRANSFORMERS.
PART 3 CONTRACT
14. EVALUATION OF LOSSES
14.1 Guaranteed Output and Losses, Liquidated Damages
Failure to meet the guaranteed outputs and losses with be dealt with as follows:
Transformer Output
If the guaranteed continuous output at rated voltage of any transformer has to be

reduced below the guaranteed value in order to maintain the temperature rises of any
part of the transformer within the guaranteed limits, liquidated damages shall be paid at
the rate of ZWD (TO BE SPECIFIED) per kVA.
Transformer Losses
If the total transformer losses of any transformer, as determined by these, without any
tolerances, at rated voltage, frequency and 100% rated kVA (on principal tapping)
exceed the guaranteed total losses, the excess in losses shall be capitalised at the rates
stated in Sub-Clause 14.2 below and the resulting amount shall be paid as liquidated
damages.
The payment on account of failure of one or more transformer to meet the guaranteed
output and guaranteed losses shall be applied individually, as the case may be, and shall
therefore be understood to be cumulative.
Rejection Limits
Should any transformer fail to meet the guaranteed output by more than 5% (five per
cent) or the total losses should exceed the total guaranteed losses by more that 1/5 (one
fifth), and should the Contractor fail within a reasonable time to modify the transformer
in order to increase the output and/or reduce the losses sufficiently, the Purchaser shall
have the option to reject the transformer.
14.2 Evaluation of Losses (TO BE STATED)
Transformer losses will be evaluated based on the following figures:
Load losses: ZWD (TO BE STATED)/kW

No load losses: ZWD (TO BE STATED)/kW
Page 30 of 52
TRANSFORMERS.
PART 3 CONTRACT
15. TECHNICAL GUARANTEE SCHEDULES
15.1 Preamble
15.1.1 The Technical Schedules shall be filled in and completed by the Bidder, and
submitted with the Bid (see example below)
DISTRIBUTION
TRANSFORMERs REF Requirement
Cla Required Required Required Required

Description Unit
use Values Values Values Values
1 Name of
Manufacturer
2 Country of
Manufacturer
3 Continuous kVA
Maximum
25 50 50 25
Rating
(C.M.R.)
4 Normal
voltage
between
phase at no
load
(a) H.V Volts 33000 33000 11000 11000
(b) LV Volts 400 400 400 400
No of phases
per
transformer 3 3 3
5 Tappings
(a) Plus % 5 5 5 5
(b) Minus % 5 5 5 5
6 Performance
Data at Sea
Level
corrected at
sea 75%
Page 31 of 52
TRANSFORMERS.
PART 3 CONTRACT
(a) No load Watts
loss at
primary
voltage 350 198 330 130
(b) No load Watts
Loss At 10%
Primary
Overvoltage 522 240 450 158
(c ) Load loss Watts
at C.M.R 1800 620 1800 580
(d) %
Impedance
C.M.R and
normal ratio ≤5 ≤5 ≤5 ≤5
(e)
Maximum
temperature
rise at C.M.R
i ) Top Deg.
oil by Cels
thermometer 55 55 55 55
ii) Deg.
Average Cels
resistance per
winding 60 60 60 60
iii) Hot Deg.
Spot Cels
corresponding
to (ii) 60 60 60 60
7 Type of
insulation in
windings
(a) H.V Enamel Enamel Enamel Enamel
Insulation Insulation Insulation Insulation
(b) LV Paper Paper Paper Paper
8 Lightning
impulse
insulation
level
(a) H.V kV pk
winding 170 170 170 170
(b) L.V kV pk
winding N/A N/A N/A N/A
(c) Tap
change
equipment
and
connections
Page 32 of 52
TRANSFORMERS.
PART 3 CONTRACT
i) To kV pk
earth 170 170 170 170
ii) kV pk
Between 1/4 of 170kV 1/4 of 170kV 1/4 of 170kV 1/4 of 170kV
contact pk pk pk pk
9 Are test Y/N
certificates
supplied
supporting the
insulation
level stated in
6 above Yes Yes Yes Yes
10 Silica Gel
Breather
i)
Make of unit
fitted
ii)
Size of unit 125 125 125 125
11 Noise dB
Pollution 48 48 48 48
12 Vector Group Dyn11 Dyn11 Dyn11 Dyn11 Dyn11
13 Dimensions
(i) Height Mm Varies varies varies varies
(ii) Width Mm Varies varies varies varies
(iii) Depth Mm Varies varies varies varies
14 Winding
Material
(i) Primary Electrolytic Electrolytic Electrolytic Electrolytic
copper copper copper copper
(ii) Secondary Electrolytic Electrolytic Electrolytic Electrolytic
copper copper copper copper
15 Colour Sea Grey Sea Grey Sea Grey Sea Grey
16 Weight
(i) Core & Kg
Winding Varies varies varies varies
(ii) Tank & Kg
Fitting Varies varies varies varies
(iii) Weight of Kg
Oil Varies varies varies varies
(iv) Total Kg
Weight Varies varies varies varies
17 Power
Frequency
Voltage
Withstand
(i) H.V. kVrms 70 70 70 70
(ii) L.V. kVrms 2.5 2.5 2.5 2.5
Page 33 of 52
TRANSFORMERS.
PART 3 CONTRACT
18 Number of
Phases 3 3 3 3
Reference IEC60
19 Standards 076 IEC60074 IEC60075 IEC60076 IEC60076
15.1.2 All documentation necessary to evaluate whether the equipment offered is in

accordance with this Specification shall be submitted with the Bid.
15.1.3 All data entered in the Schedules of Technical Guarantees are guaranteed values by
the Bidder and cannot be departed from whatsoever.
15.1.4 All data entered in the Schedules of Informative Data are also guaranteed values by
the Bidder. These data may only be altered following the Engineer's written consent.
15.1.5 Equipment or Systems offered which are not in accordance with this Specification
shall be listed in Schedule III-9.
16.0 Definitions and Abbreviations
The following terms may be met in these Technical Schedules and shall be
interpreted as follows:
Hz shall mean hertz

kW shall mean kilowatt
MW shall mean megawatt
VA (kVA, MVA) shall mean volt-ampere (kilo-, mega-)
A (kA) shall mean ampere (kilo-)
V (kV) shall mean volt (kilo-)
W/m shall mean watt per metre
AC shall mean alternating current
DC shall mean direct current
IN shall mean rated (nominal) current
UN shall mean rated (nominal) voltage
Ah shall mean ampere-hours
lm shall mean lumen
lm/w shall mean lumen per watt
min shall mean minute
min. shall mean minimum
(prefix) shall mean micro
rms shall mean root mean square
p.u. shall mean per unit
p/p shall mean peak to peak
T shall mean Tesla
kg shall mean kilogram
N shall mean Newton
l shall mean litre
s or sec. shall mean second
Page 34 of 52
TRANSFORMERS.
PART 3 CONTRACT
No. shall mean number
dB shall mean decibel
Amp shall mean amperes
F shall mean Farad
o
C shall mean centigrade
K shall mean degree Kelvin
m2 shall mean square metre (mm2 for millimetre, etc)
m3 shall mean cubic metre (mm3 for millimetre, etc)
m3/s shall mean cubic metres per second
m shall mean metre
cm shall mean centimetre
mm shall mean millimetre
joules shall mean joules per hour
tonne shall mean metric tonne
% shall mean percentage
Pascal 1 N/m2
cst shall mean centistoke
Page 35 of 52
TRANSFORMERS.
PART 3 CONTRACT
RURAL ELECTRIFICATRICATION AGENCY
TECHNICAL SPECIFICATIONS FOR SWER TRANSFORMERS
1. PARTICULARS OF ELECTRICAL SYSTEM
Unless otherwise specified in Schedule of Requirements, it must be assumed

that the system on which the equipment will operate is :
a) Single Wire Earth Return (SWER) overhead-line construction and

underground system.
b) Operated at 50 Hz, with approximately sinusoidal wave form.
c) The highest system voltage does not normally exceed the nominal
system voltage by more than 10%.
d) The system frequency variation does not exceed plus or minus 2.5%
from 50 Hz.
Designs should allow for these variations.

2. PARTICULARS OF ENVIRONMENT
The transformers shall be capable of operating under the following environmental

conditions.
a) Ambient temperatures:
(i) Maximum: 40 °C
(ii) Minimum: minus 10 °C
(iii) Maximum daily average: 35 °C
b) Altitude:
Maximum altitude of 1 500 metres above sea level. The design shall
allow for reduced cooling effect due to high altitude.
c) The transformers will be exposed to direct tropical sunlight.
d) Humidity:
Humidity of 13mg per cubic metre absolute and 65% relative before
storms with vapour pressure of 17mmHg.
Transformers will operate within the tropics and will be subjected to sudden ambient air
temperature changes of the order of 10 C per hour, occurring at the onset of rain, but
the barometric pressure at any given place does not vary by more than approximately
10mm Mercury. Frequent and severe lightning storms occur during summer months,
with isoceraunic levels varying between 50 and 100 thunderstorm days per annum.
Page 36 of 52
TRANSFORMERS.
PART 3 CONTRACT
It is the manufacturers responsibility to make himself familiar with any other climatic
and physical conditions pertaining in Zimbabwe and to allow for all conditions in his
designs.
Particular attention should be paid in the design of all equipment to ensure that there is
no possibility of damage to working parts or insulation through the ingress of dust,
insects or vermin.
All orifices and air vents should be covered by easily replaceable weather resisting,
fine mesh wire where practicable.
3. STANDARDS, UNITS AND LANGUAGE
Except where modified by the Authority's Specifications, IEC Recommendations

(IEC 76) shall apply throughout or British Standards (BS) where they amplify the
IEC 76.
In the case of conflict between the above stated Standards and this
Specification, the ruling of this Specification will prevail.
All tenders, correspondence, description upon drawings, illustrations or

instructions shall be in unambiguous English Language. SI Units of
measurements shall be used throughout.
All materials used in the manufacture of the transformers shall be new and of
high commercial quality.
The transformers shall be manufactured to high quality standards.
Type test certificates are to be submitted with the tender for each transformer
rating and voltage.
The transformers shall be sourced from manufacturers who have ISO 9001
Certification or equivalent. Documentary evidence of the ISO 9001 Certification
shall be provided with the bid. Manufacturers who cannot submit such
certification are liable to be rejected.
4. TECHNICAL SCHEDULES
The Technical Schedules shall be filled in and completed by the Bidder, and
submitted with the Bid.
a) All documentation necessary to evaluate whether the equipment offered is in

accordance with this Specification shall be submitted with the Bid.
b) All data entered in the Schedules of Technical Guarantees are guaranteed

values by the Bidder and cannot be departed from whatsoever.
Page 37 of 52
TRANSFORMERS.
PART 3 CONTRACT
c) All data entered in the Schedules of Informative Data are also guaranteed
values by the Bidder. These data may only be altered following the
Engineer's written consent.
Technical schedules A and B

SWER Distribution Transformer – Inland Application
Phase –to neutral connected transformer with centre-tapped low-voltage
Winding (16 kVA 19 kV/+240 V)
Schedule A: Purchaser’s specific requirements

Schedule B: Particulars of equipment to be supplied
Item Description Schedule A Schedule B
1 Identification
a) Manufacturer’s name
b) Country of Manufacture
2 Constructional requirements
2.1 Transformer dimensions
(shown in drawing SDT 01)
a) Ho (max.) including surge arrester mm 1 600
b) W o (max.) including surge arresters mm 1 080
c) Lo (max.) mm 1 500
d) Max. mass kg 900
e) Oil capacity l
2.2 Tank
a) Tank type: Sealed Sealed
Rigid or Corrugated
2.3 Bushings
MV bushing: Outdoor
a) Material Porcelain
b) Min. creepage distance: mm/kV 22
c) Stem diameter mm M12
d) Stem type Threaded
L V bushing: Outdoor
b) Min Creepage distance: mm/kV 22
Page 38 of 52
TRANSFORMERS.
PART 3 CONTRACT
Phase-to-neutral connected transformer with centre tapped low voltage
2.4 Dehydrating breathers Not required
2.5 Oil-level gauges Not required
Drain Valve Not required
2.6 Earthing terminals
a) Distance between L V earth terminal
and neutral bushing. mm 250 to 300
2.7 Pole-mounting brackets

(as shown in drawing SDT 01)
a) Mo mm 400
b) h1 (max.) mm 400
c) W1 (max.) mm 450
d) Provide clamp and threaded rods Yes
2.8 Winding material HV Copper

LV Copper
3 Electrical requirements
3.1 Rating
a) Nominal rating kVA 16
b) Rated primary voltage kV 19
c) Rated secondary no-load voltage V +240
d) BIL kV 200
e) Number of phases 1 ph
f) Vector symbol N/A
3.2 Losses
a) No-load losses, P1 kW 0.1 max
b) Load losses; Pc kW 0.4 max

c) cost per kW of no-load losses; C1 USD/kW $1 531.02
d) cost per kW of load losses, Cc USD/kW $181.79
3.3 Impedance Voltage

a) Impedance at principle tapping % ≤4.5
b) X/R ratio xxxxxxxx
4.0 Rating Plate and Diagram information

Requirements
Page 39 of 52
TRANSFORMERS.
PART 3 CONTRACT
I) Manufacturer Required
ii) Size in Kva Required
iii) Voltage rating Required
iv) Year of manufacture Required
v) Total weight Required
vi) Full load loss Required
vii) No load loss Required
viii) Volume of oil in litres Required
ix) REA Tender number Required
x) REA order number Required
xi) Percentage impedance Required
xii) Voltage table at various tap Required
positions
5.0 Tests
5.1 Type Tests
a) Temperature-rise test Test Report
Number
b) Lightning impulse test chopped on Test Report
tail Number
c) Short-Circuit withstand test Test Report
Number
d) Pollution test Test Report
Number
e) Equivalent disturbing current test Test Report
Number
Item Description Shedule A Schedule B
5.2 Routine Tests

a) Measurement of winding Test Report
resistance Number
b) Measurement of voltage ratio and Test Report
check of phase displacement Number
c) Measurement of short-circuit Test Report
impedance and load loss Number
d) Measurement of no-load loss and Test Report
current Number
e) 480V across outer terminals Test Report
Number
f) Separate source test Test Report
Page 40 of 52
TRANSFORMERS.
PART 3 CONTRACT
Number
g) Induced overvoltage test Test Report
Number
h) Measurement of paint thickness Test Report
Number
i) Test for effective sealing Test Report
Number
6.0 Drawings to be submitted with tender

a) Outline Drawing Drawing
Number
b) Rating and diagram plate Drawing
Number


1 Identification
c) Lo (max.) mm 1 500
d) Max. mass kg 900
e) Oil capacity l
2.2 Tank
Rigid or Corrugated
2.3 Bushings
MV bushing: Outdoor
Page 41 of 52
TRANSFORMERS.
PART 3 CONTRACT


a) Mo mm 400
b) h1 (max.) mm 400
c) W1 (max.) mm 450

LV Copper
3.1 Rating
d) BIL kV 200
f) Vector symbol xxxxxxxxx
3.2 losses

Page 42 of 52
TRANSFORMERS.
PART 3 CONTRACT
c) Impedance at principle tapping % ≤4.5
d) X/R ratio xxxxxxxx

Requirements
ii) Size in kVA Required
positions
5.0 Tests
5.1 Type Tests
f) Temperature-rise test Test Report
Number
g) Lightning impulse test chopped on Test Report
tail Number
h) Short-Circuit withstand test Test Report
Number
i) Pollution test Test Report
Number
j) Equivalent disturbing current test Test Report
Number
5.2 Routine Tests

j) Measurement of winding Test Report
resistance Number
Page 43 of 52
TRANSFORMERS.
PART 3 CONTRACT
k) Measurement of voltage ratio and Test Report
l) Measurement of short-circuit Test Report
m) Measurement of no-load loss and Test Report
current Number
n) 480V across outer terminals Test Report
Number
o) Separate source test Test Report
Number
p) Induced overvoltage test Test Report
Number
q) Measurement of paint thickness Test Report
Number
r) Test for effective sealing Test Report
Number

c) Outline Drawing Drawing
Number
d) Rating and diagram plate Drawing
Number


1 Identification
c) Lo (max.) mm 1 500
d) Max. mass kg 900
e) Oil capacity l xxxxxxxx
2.2 Tank
Page 44 of 52
TRANSFORMERS.
PART 3 CONTRACT
Rigid or Corrugated
2.3 Bushings
MV bushing: Outdoor

Winding g(64 kVA 19 kV/+240 V)

a) Mo mm 400
b) h1 (max.) mm 400
c) W1 (max.) mm 450

LV Copper
3.1 Rating
d) BIL kV 200
3.2 losses
Page 45 of 52
TRANSFORMERS.
PART 3 CONTRACT


e) Impedance at principle tapping % ≤4.5
f) X/R ratio xxxxxxxx

Requirements
positions
5.0 Tests
5.1 Type Tests
k) Temperature-rise test Test Report
Number
l) Lightning impulse test chopped on Test Report
tail Number
m) Short-Circuit withstand test Test Report
Number
n) Pollution test Test Report
Number
Page 46 of 52
TRANSFORMERS.
PART 3 CONTRACT
o) Equivalent disturbing current test Test Report
Number
5.2 Routine Tests

s) Measurement of winding Test Report
resistance Number
t) Measurement of voltage ratio and Test Report
u) Measurement of short-circuit Test Report
v) Measurement of no-load loss and Test Report
current Number
w) 480V across outer terminals Test Report
Number
x) Separate source test Test Report
Number
y) Induced overvoltage test Test Report
Number
z) Measurement of paint thickness Test Report
Number
aa) Test for effective sealing Test Report
Number

e) Outline Drawing Drawing
Number
f) Rating and diagram plate Drawing
Number
Page 47 of 52
TRANSFORMERS.
PART 3 CONTRACT

SWER Isolation Transformer (475 kVA 33kV/19 kV)– Inland Application

1 Identification
xxxxxxx
xxxxxxx
(shown in drawing SIT 01)
c) Lo (max.) mm 1 800
d) Max. mass kg 2 200
e) Oil capacity l xxxxxx
2.2 Tank
Rigid or Corrugated xxxxxxx
2.3 Bushings
MV bushing: Outdoor
b) Creepage distance: mm/kV 22

2.6 Winding material MV Copper
SWER Copper
Page 48 of 52
TRANSFORMERS.
PART 3 CONTRACT
2.7 Electrical requirements
Rating
b) Rated primary voltage (p-to-p) kV 33
c) Rated secondary voltage (p-to-g) V 19
d) MV BIL kV 200
e) SWER BIL 200
3 losses
3.1 a) No-load losses, P1 kW 1.24 max

Requirements

positions
5.0 Tests
5.1 Type Tests
p) Temperature-rise test Test Report
Number
q) Lightning impulse test chopped on Test Report
tail Number
r) Short-Circuit withstand test Test Report
Number
s) Pollution test Test Report
Number
t) Equivalent disturbing current test Test Report
Number
Page 49 of 52
TRANSFORMERS.
PART 3 CONTRACT
5.2 Routine Tests
bb) Measurement of winding Test Report
resistance Number
cc) Measurement of voltage ratio and Test Report
dd) Measurement of short-circuit Test Report
ee) Measurement of no-load loss and Test Report
current Number
ff) Separate source test Test Report
Number
gg) Induced overvoltage test Test Report
Number
hh) Measurement of paint thickness Test Report
Number
ii) Test for effective sealing Test Report
Number

g) Outline Drawing Drawing
Number
h) Rating and diagram plate Drawing
Number
NB:
All transformers will be inspected by ZESA Enterprises (Pvt) Ltd before delivery to Rural
Electrification Agency Central Stores. The cost of inspection will be borne by the supplier.
Rural Electrification Agency will accept transformers which have passed ZESA tests only.
Page 50 of 52
TRANSFORMERS.
PART 3 CONTRACT
Annexure 1
DECLARATION ON NON-ENGAGEMENT IN CORRUPT OR FRAUDULENT
PRACTICES FORM
The Chief Executive
Rural Electrification Fund
6th Floor Megawatt House
44 Samora Machel Ave
P. Bag A250,Avondale
Harare
Zimbabwe
TENDER NUMBER: ____________________________________________________
TENDER DESCRIPTION: ___________________________________________________
I___________________________________ the undersigned (Director of Company) on

behalf of ____________________________________ (Name of Organisation), do hereby
declare that our organization has not been engaged in any corrupt or unethical practices
during the subsistence of our organisation.
Name in Full ___________________________________
I. D. Number ___________________________________
Signature ______________________________________
Date __________________________________________
Page 51 of 52
TRANSFORMERS.
PART 3 CONTRACT
Annexure 2
LETTER OF TENDER (TENDER FORM)
NAME OF TENDER: Supply & Delivery of transformers
Tender Number REF/………../………/2018
TO: The Chief Executive
Rural Electrification Fund (REF)
6th Megawatt House,44 Samora Machel Avenue, Harare, Zimbabwe
We, [insert name of Tenderer], herewith enclose a Tender for selection of our firm as
Contractor/Supplier for ……………………………………………………………
We have examined the Conditions of Contract, Employer's Requirements, Schedules, the

attached. Appendix and Addenda Nos __ of the above-named Works. We have examined,
understood and checked these documents and have ascertained that they contain no errors or
other defects. We accordingly offer to design, execute and complete the Works and remedy
any defects therein, in conformity with this Tender which includes all these documents and
the enclosed Proposal, for the lump tender sum of:
USD/RTGS___________________________________
We agree to abide by this Tender until _date__/_month___/_year___ [i.e. ______ days from
the tender opening date] and it shall remain binding upon us and may be accepted at any time
before that date. We acknowledge that the Appendix to Tender forms part of this Letter of
Tender.
If this offer is accepted, we will provide the specified Performance Security, commence the
Works as soon as is reasonably practicable after the Commencement Date, and complete the
Works in accordance with the above-named documents within the Time for Completion. We
guarantee that the Works will then conform to the Schedule of Guarantees.
Unless and until a formal Agreement is prepared and executed, this Letter of Tender, together
with your written acceptance thereof, shall constitute a binding contract between us. Our
Tender is binding upon us and subject to the modifications resulting from pre-award contract
negotiations.
We understand that you are not bound to accept the lowest or any tender you may receive.
Signature _____________________________ in the capacity of ___________
Duly authorized to sign tenders for and on behalf of _________________
Address: _______________________________________
Date: _______________________________________
Page 52 of 52

May 2022 Various Transformers SPOC Final

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May 2022 Various Transformers SPOC Final

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BIDDING DOCUMENT FOR THE PROCUREMENT OF VARIOUS TRANSFORMERS.

RURAL ELECTRIFICATION FUND

Tender Closing Date: 10 June 2022 , Time:1000hrs

Tender Number: REF/Inter/05/05/2022

Date of tender advert: 12 March 2022

RURAL ELECTRIFICATION FUND

DECLARATION BY THE ACCOUNTING OFFICER IN TERMS OF SECTION 19(2)(C) OF THE

TENDER NUMBER: REF/INTER/05/05/2022

TENDER DESCRIPTION-SUPPLY AND DELIVERY OF VARIOUS TRANSFOTRMERS

Part 1: Bidding Procedures

Part 2: Statement of Requirements

PART 1: BIDDING PROCEDURES

Lots and Packages

Number of bids allowed

Submission address: Chief Executive Officer

Payment of tender fees

Review by the Special Procurement Oversight Committee

 Bidders are free to quote for one or more lots

Eligibility and Qualification Criteria

Award of Tender Criteria

Bid Submission Sheet

Procurement Reference Number:

Signature …………………………….. Name: ……………………………………

Authorised for and on behalf of:

Bidder’s Reference Number:

REF SPECIFICATION NO. 18001

2. DETERMINATION OF RESPONSIVENESS ......................................................... 17

3. PARTICULARS OF ELECTRICAL SYSTEM ....................................................... 18

4. PARTICULARS OF ENVIRONMENT .................................................................... 18

5. STANDARDS, UNITS AND LANGUAGE ............................................................. 19

6.1 General ....................................................................................................................... 20

6.2 Windings .................................................................................................................... 21

6.3 Cores .......................................................................................................................... 21

6.4 Tapping Switches ....................................................................................................... 22

6.5 Bushings ..................................................................................................................... 23

6.6 Tanks and Conservators ............................................................................................. 23

6.6.1 General ....................................................................................................................... 23

6.6.2 Tanks .......................................................................................................................... 24

6.6.3 Conservators .............................................................................................................. 24

6.7 Accessories and Fittings ............................................................................................ 25

8.0 OVERLOADING CAPABILITY .............................................................................. 26

9.0 NOISE POLLUTION ................................................................................................ 26

10. TESTS ........................................................................................................................ 27

11. PACKING AND TRANSPORT ................................................................................ 27

12. DRAWINGS AND DIAGRAMS .............................................................................. 28

12.1 Drawings to be supplied with the Tender .................................................................. 28

12.2 Drawings to be supplied with the Contract ................................................................ 28

13. MAXIMUM DIMENSIONS AND WEIGHTS REQUIRED ................................... 29

14. EVALUATION OF LOSSES .................................................................................... 30

14.1 Guaranteed Output and Losses, Liquidated Damages ............................................... 30

14.2 Evaluation of Losses (TO BE STATED).................................................................. 30

15. DELIVERY PERIOD ................................................................................................ Error! Bookmark

16. TECHNICAL SCHEDULES ..................................................................................... 31

16.1 Preamble .................................................................................................................... 31

16.2 Definitions and Abbreviations ................................................................................... 34

Spares as recommended by the supplier should be included in the scope of supply.

2.2 A Tender Determined to be substantially non-responsive will be rejected by the

3. PARTICULARS OF ELECTRICAL SYSTEM

Unless otherwise specified in Schedule of Requirements, it must be assumed that the