TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.

416 kV

Ministry of Electricity
Planning and Studies Office
Baghdad – Iraq

SPECIFICATION No. D-27

TECHNICAL SPESIFICATION OF

DISTRIBUTION TRANSFORMER 33/0.416 kV

REVISION Year 2015

TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

DISTRIBUTION TRANSFORMERS

1- SCOPE OF THE TENDER :

Tenderer are invited for the design , manufacture , testing and supply of a
33000/416 volt, oil immersed copper winding outdoor type (Directly under the sun)
transformers to be supplied complete with all necessary fittings , accessories off-
load tap changer , insulating oil and spare parts . . . etc.
The transformer is to be bolted type hermetically sealed bushing insulators on both
H.T and L.T sides for the following rating: 100, 250, 400, for 630, 1000, 1600, and
2000 KVA to be box type a valid ISO 9001 certificate required.

2- GENERAL REQUIREMENTS :
The transformers shall be of first class quality and design for continuous
satisfactory operation as continuity of supply is of prime consideration. The design
shall be allow all necessary precaution for the safety of operation and maintenance
personnel. The transformers shall operate satisfactorily under variations of load,
voltage or short circuit or other conditions which may occur on the system provided
that these variations are within the assigned rating of the apparatus. All the
equipment shall be designed to obviate the risk of accidental short circuit.

2-1 Climatic Conditions :

The materials used shall be suitable for the following climatic conditions
prevailing at the site:

2-1-1 Ambient temperature:

Highest maximum (in the shade) +55C for about 6 hrs. a day.
Lowest minimum –10C
Maximum yearly average+30C
Maximum daily average +40C

2-1-2 Temperature under sun:

Black objects under direct sunshine attain a temperature of 75 C

2-1-3 Air humidity :

Maximum 92% at 40 C
Minimum 12%
Yearly average 44%

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

2-1-4 Sand storm:

In general the atmosphere is dusty which may result in a layer of dust
being deposited on all exposed surfaces. Also fine dust particles may
penetrate even through minute openings.

2-2 Altitudes
From sea level up to (1000m)

2-3 System Data:

2-3-1High voltage side:-

-Nominal voltage 33000 Volts
-Short circuit level 25 KA at 33000 volts
-Frequency 50 HZ.
-Highest system voltage 36000 volts
-system 3- phase,3-wire system grounded with
earthing transformer to limit earth fault
current to 1000 Amp/

2-3-2Low voltage side:-

-Nominal voltage 400/230 volts
-system 3-phase,4-wire neutral solidly earthed.

-Short circuit level According to the short circuit level of H.T

and the rated power of the transformer.
2-4 Standards:
All the equipment shall be in accordance with the latest issue of the international
Electro – technical commission (IEC specification).
2-5 Deviation:
The tenderer shall particularly mention in his tender all deviations from the
specification described in these tender specifications.
2-6 Schedules:
The tender shall duly fill in the schedules A&B of guaranteed technical
particulars, prices, and delivery time schedule deviations attached to this
specification. Incomplete tenders are liable to rejection.

2-7 Guarantee:
The tenderer shall confirm than the transformer guaranteed against all
defects arising from faults design, materials and workmanship, for a period of
(12) months from commissioning or (18) months from delivery, whichever
period expires earlier.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

3- SYSTEM COPOSITION
The transformer shall operate in distribution systems where most of the network
is overhead lines and comprising partly underground cable.

4-TECHNICAL SPECIFICATION
The transformers shall be copper winding, hermetically sealed of the bolted
cover type and should have the following characteristics:-

•Rated outputs ONAN …. 100, 250, 400, 630, 1000, 1600, and 2000 KVA.
•Duty…….step-down, outdoor bushing type for rating power 100, 250,400, plug in
type for 630, 1000, 1600 and 2000 KVA
•Type: wound, 3-phase
•Rated voltage at no load …. H.V. 33kV L.V- 416 volt.
•System frequency ………50HZ
•Interphase Connection … H.V. Delta L.V- star with neutral brought out.
•Vector relationship …. . . . .. Dyn 11
•Type of Cooling …. ONAN
•Temperature rise ………(i) 45ْk in top oil by thermometer
(ii) 50ْk in winding by resistance

•The efficiency (at unity power factor and 100% of rated power) of the
transformer should be not less than the following:
1. 100 kVA ……. 98.1%
2. 250 kVA ……. 98.6%
3. 400 kVA ……. 98.7%
4. 630 kVA ……. 98.8%
5. 1000 kVA …... 98.9%
6. 1600, 2000 kVA ……99%

•The duration of the short circuit (for calculation) to rise the temp. of windings
from 1050 C to 2500 C should be not less than (5 Sec.) according to IEC 60076-part
5 –clause (4.1.5).

•The thickness of the radiator plates should be shock resistant and don’t affect
heat dissipation according to tender requirements.

•The noise level should be ≤ 55 dB at 0.3 meter distance according to IEC

standards.

•The low voltage winding must be of copper foil for 250, 400, 630, 1000, 1600,
and 2000 KVA transformers.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

•Off circuit tapings . . . . . . five tapping for + 2.5% + - 5% on the H.T winding for off
circuit operation externally. The mechanism must be of
the robust and definite position type with a click
indicating position arrived during tap changing.
•System Highest Voltage. H.V side 36 kV
•Terminal arrangement of transformers:-
-The 33 kV side terminal is to be a clamp type with eyebolt and nut suitable for
conductors up to 150 mm2 copper (for100, 250, 400 KVA). For 630, 1000, 1600,
and 2000 KVA the 33 kV side terminal is to be plug in type only.

-The low voltage terminals are to be flat bar type with holes suitable for compression
type terminal lug.
The sizes of L.V side single cable as follows:-
For 250 KVA transformer 8×1×95mm2 copper (not less than 2 holes per phase)
For 400KVA transformer 7×1×150 mm2 copper (not less than 3 holes per phase)
For 630 KVA transformer 11×1×240 mm2 copper (not less than 3 holes per phase)
For 1000 KVA transformer 14×1×240 mm2 copper (not less than 3 holes per phase)
For 1600 KVA transformer 21×1×240 mm2 copper (not less than 4 holes per phase)
For 2000 KVA transformer 28 × 1× 240 mm2 copper (not less than 5 holes per phase)
Terminal arrangement of outdoors transformers must be porcelain bushing
insulator (brown colored preferable) mounted on the top cover of transformer
for both H.T. and L.T, with arcing horn (double air gap is preferable) on H.T.
bushing for outdoor transformer only. Neutral bushing should be
distinguished from phase bushing.
- For 630, 1000, 1600, and 2000 kVA transformers should be plug-in type for H.V.
side (according to the tender requirements) with glands and cable holes suitable
for cable size of 1 x 50 mm2 , 18/30 kV.

Note: For 630, 1000, 1600, and 2000 kVA can use Bus-bar as
another alternative if needed

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

5-Fittings and Accessories:

-Terminal marking plate.
-Tapping switch.
-Valves 3 / 4 B.S.P fitted on cover and bottom of tank, switch cocks.
-Thermometer pocket.
-Lifting lugs.
-Pressure relief valve.
-Earthling terminal on tank.
-Rating and diagram plate to be chromium plated of the engraved type.
-Skid mounting to be vertical with the length of the transformer.
Oil level indicator with dry contact 10 Amp. 230 V, to be of mechanical type located on
the top cover of transformer to indicate the oil level with the temp variation, protected
by metallic envelops.
-Thermometer with dry contact 10 Amp. 230 V

6-painting
- The painting should be oil and weather (dust, humidity and heat …. etc.)
resistant type and the final coat is to be aluminum paint or equivalent.
Any alternative finishing which gives better heat radiation is accepted and
must be confirmed by calculations.
- Ministry of Electricity logo must be engraved on the cover of the transformer
at a suitable place.

7- insulating oil
The transformer is to be shipped with first filling of oil which shall be
(uninhibited insulation oil), according to the latest IEC 60296.

8 - Tender Price Evaluation (losses considerations)

8-1 Price Evaluation (losses considerations)

The following equation will be applied to calculate the cost of transformer,
considering the age of the transformer, the iron losses and copper losses and
the initial price of the transformer. This cost will be used for comparison the
values of the tender and not the initial price of the transformer.
Ie = Iron (no-load) losses: 1800 USD per kW at rated voltage and frequency.
Cu = Copper (Load) losses: 600 USD per kW at rated power and principle
tapping at 750 C.
Cost according to loss evaluation (for one transformer) = Initial price +
(Guaranteed Ie x 1800 + Guaranteed Cu x 600)

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

8-2 Loss evaluation

The tolerance permitted is +10% of the evaluated guaranteed total losses
mentioned in the offer. Any transformer with total losses more than + 10% will
be rejected. For transformer with total losses within +5% of the evaluated
guaranteed losses, no penalty shall be made. For transformers where the total
losses between 105% to 110% of the total evaluated guaranteed losses , the
contract price shall be reduced by the cost of the difference between the total
losses and the 100% of the total evaluated guaranteed losses according to the
following values.
Ie = Iron losses (kW).
Cu = Copper losses (kW).
Q = number of transformers required in the tender.
For any transformer with total losses less than 100% of the guaranteed losses ,
no variation to the contract price shall be made.
Total penalty (USD) = Q x [(Measured Ie – Guaranteed Ie) Kw x 1800 USD/kW +
(Measured Cu – Guaranteed Cu) kW x 600 USD/kW]

9- Test
9-1 Inspection:
The material shall be subjected to inspection and test by our inspectors or
international inspector at any time during manufacture.
The manufacture shall provide all inspection facilities for the said
inspection and inspection shall be made at the place of manufacture or at
international testing facilities.
The inspector shall have the right of rejecting any portion of the material at
any time during manufacture if it does not meet with the requirements of this
specification in all particulars. He shall have the right of overseeing the packing
and shipping of all material to be supplied.

9-2 Test at manufacture’s work:

Test at manufacture’s work shall comprise type tests if required and routine tests.
a-Type tests
The type test prescribed shall be carried out on one unit of each capacity
1-Test of temperature rise – clause 41 of IEC 76/1967.
2-Full – wave chopped wave impulse-voltage withstand test
clause test 45 of IEC 76/1967.
3-Cost of these tests to be borne by the manufacturer.

b- Routine tests
Each transformer shall be subjected to all the routine tests specified in
section twelve of IEC 76/1967.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

9-3 Test reports:

Five copies of the test reports will be mailed within 8 days after
the tests have taken place. These reports will indicate:
-The results of the test.
-The calculation of performance of the items.
-The guarantee figures to show that each apparatus performs the
conditions of the specification within the guaranteed limits.
9-4 Test Certificates:
The tenderer shall furnish the Electricity Commission (EC) with 6 copies
of test certificates.
No equipment shall be shipped without obtaining the (EC) inspector prior
approval of the certificates.

9-5 Witnessing tests:

Unless otherwise agreed to, all tests at the factory shall be witnessed by an
authorized representative of the (EC).
The cost of travelling & accommodation of required authorized engineers
to witness the test of the place of manufacture for required weeks, to be on
tenderer account.

10- Drawing , Instruction Book And Literature.

10-1 document to be submitted with the tender:

The following documents shall be submitted by the tenderer along with his
tender:-
A-Full technical specification of transformer including schedule A&B
of guaranteed technical particulars.
B-An outline drawing showing dimensions, terminals, equipment, and
all accessories of the transformers.
C-Catalogues of the manufacturer for transformers.
D-Valid ISO -9001 certificate of the manufacture r for transformers.
E-Test certificate for identical transformers.
F-Reference list of manufactured and exported transformers.
G-Incomplete tenders are liable to rejection.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

10-2 Document to be furnished by the successful tenderer:

Within a period of 4 months from the date of award of the contract, the
successful tenderer shall furnish the (EC) with the following documents:-
A-24 sets of prints on paper on all drawings.
B-24 copies of all instruction books and technical maintenance of the
transformer, OFF Load tap changing gear and other ancillary
equipment.
C-24 copies of instruction for erection of the equipment.
D-24 copies of spare parts list with catalogue numbers.

10-3 Language:
The language to be used in the drawings and instruction book shall be English.

10-4 Dimension:
Due to the space requirement in our system, it is important for the
participants in this tender to make sure that the dimensions of each type of the
required transformers to be as small as possible, the following table is indicative
as a maximum for each single dimension:-

Table of Dimensions
Transformer Length Width Height
KVA mm mm mm
250 1580 930 1400
400 1710 1040 1500

10-5 Approval of drawings:

The successful tenderer shall prepare and submit to the (EC) all necessary
drawings complete with explanations in due time and obtain approval of the
same before commencing manufacture.
Failure to comply with this clause shall make the equipment or parts there
of liable to rejection.

11- Packing
The supplier will pack or protect the goods in the most appropriate manner. He
will be responsible for any loss or damage arising from careless packing or
protection up to the place of final destination after completion of the inspection
and tests at the factory, each item shall be packed for export shipment. All parts
provided for shipping purposes only and which are to be removed at the time of
erection shall be conspicuously tagged.
The method of packing shall be such as to protect all the items against excessive
corrosion of dampness, and shall afford adequate protection against breakage or
other injury, or loss due to breakage of cases or crates from the time the items

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

leaves the factory until finally installed at the substation during which time, the
apparatus will travel by rail by a long sea voyage again by rail or truck to the site
of the substation. The equipment will also undoubtedly stand on wharves and in
the open during and in between periods of transportation and will thereby be
exposed to heavy rain, hot sun, humid climate and sudden changes of
temperature.
Owing to the numerous handlings, the containers should be very strong also extra
ordinary care should be given to the packing of the equipment and especially the
items having insulating material to prevent the injury due to moisture, from
sources external to the packing or from excessive condensation with the packing.

12- Spare parts and special tools for each rating

12-1 Spare parts:
1-H.T / L.T winding. 3%
2-H.T bushing with its accessories. 10%
3-L.T bushing with its accessories. 10%
4-Tap changer. 3%
5-Pressure relief valve. 2%
6-Oil level indicator. 10%
7-Cover gasket 10%
Unit price per set and per price for each item are required.

12-2 Special tools:

All special tools required for maintenance of transformer shall be included
in the scope of supply. An itemized list of special tools together with prices
shall be submitted with the tender.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

SCHEDULE (A)
SCHEDULE OF GUARANTEED PERFORMANCE AND OTHER
TECHNICAL PARTICULARS
(TO BE COMPLETED BY THE TENDERER)

Unit 100 250 400 630 1000 1600 2000

KVA KVA KVA KVA KVA KVA KVA
Tr. Tr. Tr. Tr. Tr. Tr. Tr.

1- Name of manufacturer.
2- Country of origin.
3- Standard on which performance data is based.
4- Continuous maximum rating for the specified temperature rise and ambient
temperature ONAN rating (KVA)
5- Rated temperature rise ( K )
a- Oil by thermometer.
b- Winding by resistance.
6- Hottest spot temperature rise (K).
7- No-load voltage ratio at normal tap & vector relationship.
8- Exciting current referred to H.V. and 50 Hz at ..… – (Amps)
a- 90% rated voltage.
b- 100% rated voltage.
c- 110% rated voltage.
9- Power factor of exciting current at 100% rated voltage and 50 Hz…..
10- Iron losses at 50 HZ …… (kW).
a- 90% rated voltage.
b- 100% rated voltage.
c- 110% rated voltage.
11- Copper losses at full load (on rating) and at 750 C …..… (kW)
12- Total losses ….…... (kW).
13- Resistance voltage at full load and 750C ……. (%).
14- Reactance voltage at full load and 75 0C ……. (%)
15- Impedance voltage at full load and 75 0C ……. (%)
a- At normal tap.
b- At highest tap.
c- At lowest tap.
16- Resistance of H.V. winding per phase at 200C ……. (ohms).
17- Resistance of L.V. winding per phase at 20 0C……. (ohms).
18- Regulation at full load at 75 0C ……. (%)
a- 1.0 power factor.
b- 0.8 P.F lagging.

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

19- Efficiency at 750C …….. (%)

a- 100% load
b- 75% load
c- 50% load
d- 25% load
20- Calculated thermal time constant …….. (Hrs).
21- Maximum flux density at normal voltage and frequency and at normal ratio
… (KI/sq.cm)
a- core
b- yoke
22- Maximum flux density at 110% voltage and frequency and at normal
voltage and frequency and at normal ratio ……… (KI/sq.cm)
a- Core
b- Yoke

23- Insulation of
a- Core bolts
b- Core bolts washer
c- Side plates
d- Core laminations

24- Current destiny in windings – Amps/sq.cm.

a- H.V. winding
b- L.V. winding

25- Insulation on copper

26- Insulation strength of winding.
a- Impulse full wave …….(kV)
(i) H.V.
(ii) L.V.
b- Impulse chopped wave ………(kV)
(i) H.V.
(ii) L.V.
c- Applied voltage test ……… kV)
d-Induced voltage test ……… (kV)

27- Insulation strength of terminals.

a-Over voltage test ………(kV)
b- Minimum wet withstand voltage ……… (kV)
c-Minimum impulse withstand ……… (kV)
d- Minimum puncture or oil-immersed withstand voltage …..(kV)

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

28- Type of core

29- Tap changer
a- Manufacturer
b- Type
c- Step of one tap in per cent of rated voltage
30- Thickness of transformer tank …….. (mm)
a- Sides
b- Bottom
c- Corrugated radiators
31- Weights and dimensions
a-Net weight of core …….. (Kg)
b-Net weight of copper …….. (Kg)
(i) H.V.
(ii) L.V.
c-Net untanking weight of
(i) Core …….. (Kg)
(ii) Frame ……..(Kg)
(iii) Coil …….. (Kg)
d- Volume of insulating oil ……..(liter)
e- Net weight of insulating oil ……… (Kg)
f- Total weight of transformer less oil ……..(tons)
g- Weight of the largest shipping package …….. (tons)
h- Crane lift for untanking core and coils ……… (m)
i- Crane lift for removal of bushings ……… (m)
j- Dimensions of transformer ………. (m)
(i) Under base to top most point
(ii) Under base to bushing mounting flanges
(iii) Overall breadth
(iv) Overall length
k- Overall shipping dimensions of tee largest package.
32-Noise level …dB at 0.3 (m)

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TECHNICAL SPESIFICATION OF DISTRIBUTION TRANSFORMER 33/0.416 kV

SCHEDULE (B)
OIL CHARACTERISTICS TABLE (TO BE COMPLETED BY THE TENDERER)
NO. DESCRIPTION SPECIFICATIONS UNIT
1. MAKER’S NAME
2. REFERENCE NAME OF OIL
3. SLUDGE VALUE (Wt %)
4. FLASH POINT (CLOSED) C 0

5. POUR POINT C 0

6. VISCOSITY AT:
a. 400 C mm2 /s
b. -300 C mm2 /s
7. ELECTRIC STRENGTH (BREAKDOWN (KV)
8. ACIDITY(NEUTRALIZATION VALUE)
a. TOTAL mg KOH/g
b. INORGANIC mg KOH/g
9. COPPER DISCELERATION
10. CRACKLE
11. SPECIFIC GRAVITY
12. SULFER CONTENT
13. DIELECTRIC DISSIPATION FACTOR (tan δ)

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