annex (a) technical specifications for distribution

Annex (A)

Technical Specifications for

Distribution Transformers

PART 1: GENERAL

1. Scope

This specification covers the design, manufacturing, testing, supply, delivery and

performance requirements of three phase 11/0.416 kV outdoor type distribution

transformers for use in the electricity distribution networks of Iraq.

2. Standards

The equipment shall comply with the latest editions and amendments of the

international standards listed below as a minimum.

IEC International Electrotechnical Commission:

IEC 60071: Insulation co-ordination

IEC 60076: Power transformers

IEC 60137: Bushing for alternating voltages above 1,000V

IEC 60156: Method for the determination of the electric strength of

insulting oils

IEC 60296: Specification for unused mineral insulating oils for

transformer and switchgear

IEC 60354: Loading guide for oil-immersed power transformers

IEC 60437: Radio interference test on high-voltage insulators

IEC 60551: Determination of transformer and reactor sound levels

IEC 60616: Terminal and tapping markings for power transformers

IEC 60722: Guide to the lightning impulse and switching impulse

testing of power transformers and reactors

ISO International Organization for Standardization:

ISO 1459: Metallic coatings - Protection against Corrosion by Hot

Dip Galvanising - Guiding Principles

ISO 1460: Metallic coatings - Hot dip galvanized coatings on

ferrous materials. Gravimetric determination of the

mass per unit area

ISO 2178: Non-magnetic coatings on magnetic substrates -

Measurements of coating thickness - Magnetic method

ISO 9000: Quality management and quality assurance standards -

Guidelines for selection and use

CENELEC/CEN Harmonized European Standards:

HD 428: Distribution Transformers

ASTM American Society for Testing and Materials:

D 202: Methods of sampling and testing untreated paper used for

electrical insulation.

Where any provision of this specification differs from those of the standards

listed above, the provision of this specification shall apply. In case of conflict,

the order of precedence shall be:

This specification

IEC standards

ISO standards

Other standards

Equipment confirming to alternative standards may be accepted provided it is

demonstrated that they give a degree of quality and performance equivalent or

better than that of the reference standards. Acceptability of any alternative

standard is at the discretion of the Employer.

3. Service Conditions

Transformers will be installed outdoors, at ambient conditions given below.

3.1 Outdoor

Item Description

Altitude above sea level: Up to 1,000m above sea-level

Ambient Temperature:

Maximum outdoor - shade +55 °C for 6 hours a day

Minimum outdoor -10 °C

Maximum outdoor daily average +40 °C

Maximum outdoor yearly average +30 °C

Maximum ground at depth 1 m +35 C

Maximum Black Body (black objects in direct sun) +80 C

Relative Humidity:

Maximum 92 %

Minimum 12 %

Yearly Average 44 %

Maximum wind velocity: 140 kilometre per hour

Rainfall per year:

Maximum 500 mm

Minimum 50 mm

Maximum in one day 65 mm

Yearly Average 150 mm

Atmosphere: Subject to sand storms and

wind blown dust

Average number of days per year of dust storms 30

Average number of days per year of thunder storms 15

4. System Conditions

The network design information is as follows;

Note: The 11 kV networks are normally operated with the neutral point earthed

through a resistor to limit earth fault current. However, the 11 kV networks

may also be operated with the neutral isolated from earth during abnormal

conditions. The unearthed 11 kV equipment shall be suitable for continuous

operation with an earth fault on one phase and shall be designed to

withstand the over voltage that may occur due to arcing to earth.

5. Inspection, Testing and Quality Assurance

5.1 Inspection

The Contractor shall submit a detailed program covering the design,

manufacture and testing of the Distribution Transformers within one month of

receipt of the contract award. Reports shall subsequently be submitted at

intervals, outlining progress.

The Employer or its nominated entity shall have free entry at all times, while

work on the contract is being performed, to all parts of the manufacturer’s

works which concern the processing of the work. The manufacturer shall

afford the Employer without charge, all reasonable facilities to verify that the

equipment being furnished is in accordance with this specification.

5.2 Testing

The equipment shall have been type tested and successfully passed all type

tests referred to in Part 2 “Technical”, and in the most recent editions of the

standards referenced in Clause 2. Certificates of type tests already carried out

shall be submitted with the bid for evaluation.

Fresh type tests shall be carried out if required by the Employer at an

independent certified/accredited testing laboratory and witnessed by the

Employer or some other representative acceptable to the Employer. If the

Employer wishes to witness tests, then the Contractor shall give the Employer

a minimum of one-month notice that the equipment/material is ready for

Description Voltage

11 kV 400 V Nominal Voltage 11 kV 400/230 V Highest System Voltage 12 kV 416 V Number of Phases 3 3 Frequency 50 Hz 50 Hz Neutral Point See Note below Directly Earthed 3 Phase Short Circuit Level 25 kA 10 kA Duration of Short Circuit 1 sec - Insulation Levels:

Impulse 75 kV - Power Frequency 1 min 28 kV 3 kV

testing. If the Employer does not indicate an intention to participate in the

testing, the manufacturer shall carry out the tests and the Contractor shall

furnish the results thereof to the Employer for review and acceptance. Cost of

type tests shall be included in the Price Schedule.

All routine tests required by the relevant standards shall be carried out even

though they are not listed in this specification, at the expense of the Contractor

and these tests shall be carried out at the manufacturer’s works. The

Contractor shall submit full details of the proposed methods of testing,

including connection diagrams to the Employer for approval, at least one

month before testing.

The Contractor shall submit to the Employer five signed copies of the test

certificates, giving results of the prescribed tests. Equipment shall not be

dispatched until the Employer has received the test certificates and the

Contractor has been informed that they are acceptable. The Employer

reserves the right to reject any item of the equipment if the test results do

not comply with the values specified or with the data given in the Schedule

of Technical Data.

5.3 Quality Assurance

The manufacturer must operate a quality assurance system that complies with

ISO 9000. The Contractor shall provide current certification showing the

manufacturers’ compliance with ISO 9000 or equivalent national standard.

The certificate must have been issued by an independent, accredited issuing

authority.

6. Spare Parts

Not required.

7. Packing, Shipping and Hazardous Substances

7.1 Packing

All equipment, including accessories, shall be packed and securely clamped

against movement in robust, non-returnable packing cases to ensure safe transit

from the manufacturer's works to the agreed point of delivery. The base of the

packing case shall be strong enough to carry the weight of the transformer and be

large enough so that no part of the transformer and accessories such as pipes,

valves, etc extends beyond the edge of the pallet.

Transformers shall be supplied filled with oil. The weight and volume of oil in

the transformer shall be clearly stated.

All the spare parts shall be packed for long storage.

Internal surfaces of equipment and accessories shall be sealed off by means of

gaskets and blanking off plates. Equipment and surfaces liable to deterioration

due to condensation shall be protected by packs of silica gel or other approved

desiccant.

Each transformer shall have 2 suitable plywood labels tied to it on adjacent sides.

Each label shall contain the following information indelibly marked on it:

Individual serial number

Employer’s name

Contract number

Contractor's name

Manufacturer’s name

Description of contents

Country of origin

Case measurements

Gross and net weights in kilograms

All necessary slinging and stacking instructions

The label and ties shall be fixed such that no damage or abrasion is caused to the

paintwork.

Each transformer shall contain a fully detailed packing list in a sealed waterproof

envelope robustly attached to it. Five (5) copies of each packing list shall be sent

to the Employer prior to dispatching the equipment.

7.2 Hazardous Substances

The Contractor shall submit safety data sheets for all hazardous substances used

with the equipment. These substances shall be classified in accordance with the

European Union SI 426.

If such substances are not used in with the equipment, the Contractor shall

give an assurance that there are no substances classified as hazardous in the

equipment supplied.

8. Submittals Required by Employer after Contract Award

The Contractor shall submit a detailed programme covering the manufacture,

testing and delivery of the materials and equipment within the time stated in the

following table.

# Description Delivery Time Objective No. of

Copies

1. Programme for production and

testing

Within one month

of contract award Approval 3

2.

Detailed dimension drawings for

all components, general

arrangement drawings showing

detailed component layout and

overall assembly drawings

# Description Delivery Time Objective No. of

Copies

3. Detailed drawing of mounting

arrangements

4. Certificates of compliance and

certificates of origin

5. Progress reports At agreed

intervals Monitoring 3

6. Notification of inspection and

tests One month before

inspection /

testing

Review and

necessary

action

3

7. List of tests and description of

the tests to be performed Approval 3

8.

Test reports for all type tests,

routine tests and special tests

and inspection reports

Immediately after

tests/inspection

are completed

Approval 5

9. Technical Data Schedule with

approved revisions if any

One month before

delivery Approval

5

10. Detailed schematic and wiring

drawings for all components 5

11.

General description of the

equipment and all components

including brochures

5

12. Installation and commissioning

instructions 5

13. Operation and maintenance

instructions manual 5

The programme for production and testing should be in the form of a Gantt

chart.

The Contractor shall submit progress reports detailing progress against this

programme and explaining any variations. The progress reports shall be

submitted at defined intervals agreed by the Employer.

At each of the approval stages indicated in above table, the Contractor should

not proceed to the next step in the programme until the Employer gives

approval.

PART 2: TECHNICAL

9. General

This specification covers the design, manufacturing, testing, supply, delivery and

performance requirements of three phase, 50 Hz, 11/0.416 kV distribution power

transformers with accessories.

All transformers shall have separate primary and secondary windings and be

hermetically sealed, oil immersed with natural oil and air cooling (ONAN).

The design of the tank, fittings, bushings, etc. shall be such that it will not be

necessary to keep the transformer energized to prevent deterioration as the

transformers may be held in reserve, outdoors, for many years.

10. Technical Requirements

Description Requirement

Rated Voltage HV 11 kV

LV 416 V

Frequency 50 Hz

Number of Phases 3

Power ratings 100kVA, 250 kVA, 400 kVA and 630 kVA

Type Oil immersed, hermetically sealed (bolted type)

Standard IEC 60076

Cooling Self-cooled (ONAN)

Voltage Variation Off-load tap changer with 5 positions in the HV winding

giving + 2 x 2.5 %.

Windings Copper only

Core Grain orientated silicon steel, step-lap mitered joints

HV and LV Bushings Outdoor type

Vector Group Dyn11

10.1 Rated Power

The continuous rating of the distribution Transformers shall be 100kVA, 250

kVA, 400 kVA and 630 kVA.

Each Transformer shall be capable of supplying its rated power being the product

of rated voltage and rated current on the line side winding (at center tap)

expressed in kVA, as defined in IEC 60076-1.

The transformer shall also be capable of delivering rated current at an applied

voltage equal to 105% of the rated voltage.

- Likewise, each transformer shall be capable of supplying its rated power

continuously under ambient temperature conditions without the

temperature rise of the top oil exceeding 50 C and without the temperature

rise of the windings as measured by resistance exceeding 55 C.

10.2 Overload Capacity

The transformer shall be capable of operating in accordance with the loading

guidelines of IEC 60354 without exceeding the normal daily use of life and

without the transformer winding hot spot temperature exceeding 140 C.

The Contractor shall submit calculations demonstrating that above requirements

are met. These calculations shall disregard the effect of winding thermal

capacity.

Importance is attached to overload capacity. Transformers incapable of meeting

the overload performance specified will not be considered.

10.3 Impedance Voltage

The guaranteed value of impedance measured at 75 C and center tap shall be

4% for the transformers of 100kVA, 250 kVA and 400 kVA capacities and 6%

for the distribution transformers of 630 kVA capacity and it shall be subject to

the tolerance specified in IEC 60076.

The resistance component of impedance measured at 75 C on the center tap

shall not exceed 25 % for all kVA ratings

10.4 Short Circuit Performance

The transformer shall be capable of withstanding the thermal and dynamic

effects of short circuits. System short circuit level and the withstanding duration

are given in table “system conditions” in section 3.2.

The short circuit characteristics shall be as follows;

The X/R ratio shall conform to HD 398 / HD 428

The initial winding hot spot temperature shall be 98 C

The final winding hot spot temperature shall be 250 C

The ability to withstand the thermal and dynamic effects of a short circuit shall

be demonstrated in accordance with IEC 60076 and IEC 60354. Calculations /

test certificates shall be submitted for approval.

10.5 Flux Density

The flux density at any point of the magnetic circuit when the transformer is

connected on the centre tap and operating at normal voltage and frequency shall

not exceed 1.65 Tesla. Saturation must not occur at 10 % over voltage.

10.6 Noise Level

The average noise level of the transformers shall not exceed the values given in

IEC 60551. The measurements shall be carried out in accordance with the above

standard at a distance of 300 mm from the envelope of the transformer.

10.7 Tap Changing Characteristics

Each transformer shall be fitted with 5 taps with ± 2x2.5% voltage variation. Tap

changing and the tap changing mechanism shall have the following

characteristics:

Tap changing shall be carried out with the transformer off-load. An

externally operated self-positioning tapping switch shall be provided.

Provision shall be made for locking the tap switch handle with a padlock

having a 6 mm diameter hasp.

Tap changer handles shall be fitted with gasketed covers, so that sealing

of the transformer under normal conditions is independent of the switch

shaft gland.

11. Materials and Construction

11.1 Core and Coils

The HV and LV windings shall be made of high conductivity copper. Copper

foil may be used for the LV winding.

The windings shall be uniformly insulated and the LV neutral point shall be

insulated for full voltage. The insulation material of windings and connections

shall be high quality, free from insulation softening, shrinking or collapsing

during service. Moreover none of the material used shall disintegrate, carbonize

or become brittle under the action of hot oil, under all load conditions.

The core shall be manufactured from non-aging, grain-orientated silicon steel of

high permeability with step-lap mitered joints.

The core and coil assembly shall have the core and coils rigidly connected to the

tank and suitable closed lugs shall be provided for removing the core and coil

assembly from the tank.

11.2 Bushings and Terminals

All bushings shall be so designed that there will be no excessive stressing of

any parts due to temperature changes and adequate means shall be provided to

accommodate conductor expansion. Insulation levels for bushings shall be at

least equal to those specified for the windings.

The Bushings shall be so installed that they are easy to be checked and

removed without removing the tank cover and the pipe work.

The creepage distances for the bushings and the insulators shall not be less than

25 mm/kV for maximum phase to phase system voltage.

Both HV and LV Bushings shall be complete with Brass terminals suitable for

terminating Copper conductors as details given below:

HV: outdoor bushings with clamp for terminating 50-95 mm2 Copper

Conductor

LV: outdoor bushings with terminals suitable for terminating copper cables

as specified below.

100 kVA – 1x1C 95 mm2

250 kVA – 2x1C 95 mm2

400 kVA – 3x1C 150 mm2

630 kVA – 4x1C 150 mm2

The HV and LV bushings shall be:

Easily replaceable and cemented in bushings are not acceptable.

Sufficiently robust to withstand normal transport hazards.

The HV bushings shall be labeled in accordance with IEC 60076. Letters shall be

at least 12 mm high. The means of marking shall be either:

Engraved metal plate or etched anodized aluminium. Identification by

adhesive stickers is not acceptable.

If labeling is to be carried out on the tank, it is preferred that one plate be

used rather than individual markings for each phase, in order to prevent

incorrect phase markings.

11.3 Earthing Terminals

All transformers shall be provided with a main earthing terminal of stainless steel

welded to the tank and be fitted with a stainless steel M12 bolt, nut, spring

washer and a lock washer.

11.4 Tank Fabrication

The transformer tank shall be of rigid construction, shall not leak and shall be

designed so that the completed transformer can be lifted and transported without

permanent deformation or oil leakage. The Contractor shall state what method

of leak testing is used.

The tank shall be fabricated of mild steel or stainless steel. If stainless steel is

used it shall not discolour or corrode; a minimum grade 304 L is required.

The minimum thickness of the steel tank shall be 3 mm for mild steel and an

equivalent thickness for stainless steel such that its mechanical strength shall be

the same as that of the 3 mm thick mild steel tank. Thickness below the

minimum value will be considered only in exceptional cases, such as where

special protective finishes are used. The Contractor shall provide full information

about any such special finish, including any field experience.

The transformer tank and the top cover shall be designed in such a manner as to

leave no external pockets in which water can lodge or dust deposits can build up.

The top cover shall be of the bolted type and fitted with neoprene bonded cork

seals suitable for temperature as stipulated in this specification. Surfaces at

gasketed joints shall be such that an even face is presented to the gasket, thereby

eliminating the necessity for the gasket to take up surface irregularities.

The cooling surfaces may be oil filled fins or radiators. Only larger faces of the

transformer shall be used to attach cooling surfaces.

All pipes and radiators, which are welded to the tank wall, shall be welded

externally.

100kVA, 250 kVA and 400 kVA transformers shall be pole mounted and 630

kVA transformers shall be wheel mounted. Skids shall be aligned at right angles

to the line of the HV bushings.

11.5 Surface Treatment

The transformer tank, radiators and accessories should be adequately protected

against corrosion and the Contractor shall submit details of the proposed method

of protection.

All surfaces shall be thoroughly cleaned of rust, scale, grease and dirt and other

foreign matter and all imperfections shall be removed by means of approved

methods.

The transformer tank and its steel attachments shall be hot dip galvanized or

metallized, followed by painting. The painting system used should be proven and

documented.

The outside of the tank shall be painted Gray.

The inside of the tank shall be painted with an approved oil resisting varnish so

that the oil cannot come into contact with the tank metal at any time.

11.6 Tank Fittings and Attachments

The following fittings and attachments shall be provided in all transformers:

Tap changer (off-circuit with pad lockable switch)

HV bushing assembly

LV bushings assembly

Oil filling and drain valves

Main earthing terminal

Lifting eyes pulling eyes and jacking pads

Stainless steel engraved rating and connection plate in both Arabic and

English languages

Pressure relief valve

Protecting irons

Oil level indicator

Terminal marking

11.7 Transformer Assembly

The core and winding shall be dried in a vacuum drying oven. The heating and

vacuum drying cycle shall be approved by the Employer. The tank, complete

with core and windings, shall be filled with oil under a vacuum.

11.8 Transformer Oil

The transformers shall be supplied filled with class 1 mineral oil conforming to

IEC 60296. The Contractor shall submit a detailed specification for the type of

oil proposed. The oil shall not contain polychlorinated biphenyls (PCB). The

Employer may require evidence that the oil is not contaminated by PCB. If an

anti oxidant is recommended, its use shall be subject to the Employer's approval.

12. Transformer Losses

The Contractor shall state the guaranteed losses. No positive tolerance is

allowable on the guaranteed values. Transformers supplied with losses exceeding

the guaranteed values will be rejected.

The Contractor shall also state the value of guaranteed magnetizing current,

subject to the tolerance specified in IEC 60076.

12.1 Loss Evaluation

The admissible tolerances for component and total losses of transformer after

testing shall be according to IEC 60076.

The Employer may at its sole discretion reject any transformer with Copper

losses or Iron losses exceeding the relevant tolerances.

For the purpose of evaluation the transformer shall be evaluated according to the

total price plus the capitalized value of losses. The formula to be used in

evaluation will be:

Capitalized Cost = $T + (Fe x $5,000) + (Cu x $1,200) Where,

$T = The total cost of the transformer as tendered.

Fe = No load loss in kW

Cu = Load loss in kW at full rated load and maximum operating

temperature.

13. Tests

The tests listed hereinafter shall be carried out in accordance with provisions

in the referenced standards in the specification.

13.1 Routine Tests

Routine tests shall be carried out on all transformers and the tests shall be

conducted in accordance with IEC 60076 /other standards as applicable.

The following routine measurements and tests shall be carried out:

Measurement of winding resistance

Measurement of voltage ratio and check of polarity and vector group

Measurement of impedance voltages

Measurement of load losses

Measurement of no load losses and no load current, including

measurement of harmonics

Induced overvoltage withstand test

Separate source voltage-withstand tests on HV and LV windings

Bushing routine tests

Oil leakage test

Relief Device test

Dielectric Routine Tests

Galvanizing tests.

13.2 Type Tests

Following shall be regarded as type tests:

Temperature Rise Test. This test shall be carried out on the tap

having maximum losses

Short Circuit Withstand test

Measurement of zero-sequence Impedances

Impulse Voltage Test and Power Frequency Test

Acoustic Sound Level Measurement

Tank Vacuum Test

Measurement of Harmonic Level in no load condition

Oil Analysis

13.3 Galvanizing Tests

Galvanizing tests shall be carried out on transformer tanks prior to painting.

Those shall be routine tests, which shall be part of the routine tests

documentation and shall not be charged to the Employer. Testing shall be in

accordance with ISO 1460 and is summarized as follows.

The following tests, measurements or inspections shall be carried out on each of

the selected samples:

Visual inspection

Thickness of galvanizing coat

Uniformity of galvanizing coat

In the event of disagreement or dispute over the results of the above tests a

coating mass test shall be carried out. The result of this test shall be definite and

binding.

14. Label and Rating Plates

Labels, name plates, markings and instructions shall be clear and indelible and

in the English language. A weatherproof rating plate shall be provided in

accordance with IEC 60076 and showing the following items, indelibly

marked:

- Type of transformer

- Specification to which standard it was manufactured

- Manufacturer’s name

- Serial number

- Year of manufacturer

- Number of phases

- Rated power

- Rated frequency

- Rated voltage

- Rated currents

- Vector group

- Percentage impedance voltage at rated current

- Type of cooling

- Continuous ambient temperature at which ratings apply

- Top oil temperature rise at rated load

- Total weight

- Volume of oil

- Weight of core and windings

- Table of primary voltages at the 5 tapping positions

- Connection diagram

- Employer’s name

15. Drawings

Typical mounting arrangement of pole-mounted transformers is shown in the following

drawings.

15.1 100kVA - 250 kVA Transformer

15.2 400 kVA Transformer

SCHEDULES TO BE COMPLETED BY THE BIDDERS

1. Technical Data Schedule

The following Technical Schedule shall be filled out separately for each transformer

rating.

1.1 Technical Data Schedule for 100 kVA Distribution Transformer

# Description Unit Data

1 International standards transformer complies with - 2 Nominal frequency Hz 3 Rated Power kVA 4 Nominal primary voltage kV 5 Nominal secondary voltage V 6 Rated primary voltage kV 7 Rated secondary voltage V 8 Type of cooling - 9 Vector group - 10

Tap changing Number of steps ± steps

Tapping range ± % 11

Rated short circuit current

and withstanding duration

Current kA 12 Duration s 13 Impedance measured at 75 C and center tap % 14 X/R ratio -

15 Duration of overload

25 % overload C

minutes

50% overload C

minutes 16 Design maximum outdoor temperature C 17 Design continuous ambient temperature C 18

Thermal Characteristics

Average winding temperature rise C

Maximum average temperature rise C

Maximum hot spot temperature rise C

Hot-spot to top-oil temperature gradient C 19 Magnetic flux density Tesla 20 Core Losses W 21 Winding losses W 22 No load current A 23 Regulation: full load, PF=1

full load, PF=0.85 % %

24 Silicon steel

Manufacturer Type and grade

# Description Unit Data Operating flux density Tesla

Losses kW/kg at operating flux density kW/kg

Manufacturer’s data sheet supplied Yes/No


25

Conductor for HV winding

Manufacturer/Supplier and type

Conductor Material

Shape and cross sectional area 26

Conductor for LV winding


Conductor Material


HV Bushing

Manufacturer/Supplier

Type and grade

Bushing catalogue number 28

LV Bushing


Type and grade

Bushing catalogue number 29 Bushing basic impulse

level HV Bushing kV

30 Bushing power frequency withstand voltage

HV Bushing kV

LV Bushing kV 31

Terminals

Type and metal used in HV terminal

Type and metal used in LV terminal

Type of metal used in Earth terminal 32 Minimum phase to phase clearance mm 33 Minimum phase to earth clearance mm 34 Spring and lock washers included Yes/No 35

Tap changer

Manufacturer/supplier

Type

Catalogue details attached Yes/No

Manufacturers data sheet attached Yes/No 36 Can tap changer switch be locked Yes/No 37

Tank Fabrication

Tank material Thickness of the metal sheet Painting method details attached Yes/No

38

Tank Dimensions

Width mm Height mm Depth mm

39 Transformer weights Weight of core and windings kg

Weight of tank kg Weight of oil at 20 C kg Total weight of transformer, ready for

service kg

Shipping weight of transformer kg

Signature: ______________ Company Seal Date:










25 % overload C

minutes

50% overload C








24

Silicon steel


Operating flux density Tesla




25



Conductor Material




Conductor Material


HV Bushing


Type and grade


LV Bushing


Type and grade


level HV Bushing kV


HV Bushing kV

LV Bushing kV 31

Terminals




Tap changer


Type



Tank Fabrication


38

Tank Dimensions


39

Transformer weights

Weight of core and windings kg Weight of tank kg Weight of oil at 20 C kg Total weight of transformer, ready for

service kg


Signature: ___________________ Company Seal










25 % overload C

minutes

50% overload C








24

Silicon steel


Operating flux density Tesla





25



Conductor Material




Conductor Material


HV Bushing


Type and grade


LV Bushing


Type and grade


level HV Bushing kV


HV Bushing kV

LV Bushing kV 31

Terminals




Tap changer


Type



Tank Fabrication


38

Tank Dimensions


39 Transformer weights

Weight of core and windings kg Weight of tank kg

Weight of oil at 20 C kg Total weight of transformer, ready for

service kg



2. Schedule of Non Compliance

On this schedule, the Contractor shall provide a list of non-compliances with this

specification, documenting the effects that such non-compliance is likely to have

on the equipment's life and operating characteristics. Each non-compliance shall

be referred to the relevant specification clause.

2.1 Schedule of Non Compliance - 100 kVA Distribution Transformer

Clause No Non Compliance


Claus

e No

Non Compliance


Clause No Non Compliance


Date: _____________________

3. Schedule of Test Certificates

On this schedule, a list of the test certificates shall be provided. This list shall

include type test certificates and sample routine test reports. Each certificate

listed shall be referred to the relevant specification clause.

3.1 Schedule of Test Certificates for 100 kVA Distribution Transformer

Clause No Type Test Certificate and Routine Test Report





Signature: ________________________ Company Seal

Date: ______________________

ELECTRICITY COMMISSIONPLANNING AND STUDY DEP

BAGHDAD, REPUBLIC OF IRAQ

SPECIFICATION No. D-26

DISTRIBUTION TRANSFORMERkV

REVISION YEAR 2001

DISTRIBUTION TRANSFORMERS

1- SCOPE OF THE TENDER :

Tenderer are invited for the design , manufacture , testing and supply of a11000/416 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 hermetically sealed (without conservator tank)bolted coverwith bushing insulators on both H.T and L.T sides for the following rating : 100 ,250 , 400 , Box type for rating 630 and 1000 KVA .And a valid ISO 9001 certificate.

2- GENERAL REQUIREMENTS :

The transformers shall be of first class quality and design for continuoussatisfactory operation as continuity of supply is of prime consideration . the designshall be allow all necessary precaution for the safety of operation and maintenancepersonnel . the transformers shall operate satisfactorily under variations of load ,voltage or short circuit or other conditions which may occur on the system providedthat these variations are within the assigned rating of the apparatus. All theequipment 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 10CMaximum yearly average+30CMaximum daily average +40C

2-1-2 Sun Temperature:Black objects under direct sunshine attain a temperature of 80 C .

2-1-3 Air humidity :Maximum 92% at 40 C

Minimum 12% Yearly average 44%

2-1-4 Sand storm:In general the atmosphere is dusty which may result in a layer ofdust being deposited on all exposed surfaces. Also fine dustparticles may penetrate even through minute openings.

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

2-3 System Data:

2-3-1 High voltage side:-Nominal voltageShort circuit levelFrequencyHighest system voltagesystem

11000 Volts25 KA at 11000 volts50 HZ.12000 volts3- phase,3-wire with neutral isolated butprovision is made for earthling through anearthling resistance of 21.1 ohms to limitthe earth fault current to 300 Amp.

2-3-2 Low voltage side:-Nominal voltage: 416/240 volts ssystem

Short circuit level

phase,4-wire neutral solidlyearthed.

According to the short circuit level ofH.T side and the rated power of thetransformer

2-4 Standards:All the equipments 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 specification.

2-6 Schedules:The tender shall duly fill in the schedules A&B of guaranteed technical

particulars , prices , delivery and 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 arrivals, whichever periodexpires earlier.

3- system compositionThe transformer shall operate in distribution systems where most of the net workis overhead lines and comprising partly underground cable.

4- TECHNICAL SPECIFICATION

The transformers shall be copper winding. Hermetically sealed of the blolted cover andshould have the following characteristics:-

KVA.ep-down, outdoor bushing type for 100,250,400,Box type for 630 & 1000

KVH.-phase

- 416 volt.

- star with neutral brought out.Vector rel

C in top oil by thermometer (ii) 50 C in winding byresistance.

Off circuit tapings . . . . . . five tapping for 2.5% - 5% on the H.T winding for offcircuit operation externally. The machine must be ofthe robust and definite position type with a clickindicating position arrived during tap changing.

System Highest Voltage . . H.V side 12 kVTerminal arrangement of transformers:-

The 11 kV side terminal is to be a clamp type with eyebolt and nut suitable forconductors up to 150 mm2 copper.

The low voltage terminal are to be flat bar type with holes suitable forcompression type thimble the sizes of L.V side:For 100 KVA transformer 4x1x70 mm2 copper.For 250 KVA transformer 6x1x195+1 70 mm2 copperFor 400KVA transformer 7x1x150 mm2 copperFor 630 KVA transformer 11x1x240 mm2 copperFor 1000 KVA transformer 14x1x240 mm2 copper

Terminal arrangement of outdoors transformers must be brown colored bushinginsulator mounted on the top cover of transformer for both H.T. and L.T, with arcinghorn on H.T.bushing for outdoor transformer only. Neutral bushing shoulddistinguished from phase bushing,

- For box-type transformer a suitable iron box cover the top bushings.

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 , to be of mechanical type located on the top cover of

transformer to avoid oil leakage , covered by metallic envelop.

6- paintingA primary coat shall be applied immediately after cleaning all ungalvanized

metallic parts thoroughly. An oil and weather resistant type second coat shall thenbe applied and the transformer finished in aluminum paint.

7- insulating oilThe transformer is to be shipped with first filling of oil which shall be SHELL

DIALA (B).

8- loss evaluationThe tolerance permitted is +10% of the evaluated guaranteed total losses

mentioned in the offer. Any transformer with total losses more than + 10% will berejected. For transformer with total losses within +5% of the evaluated guaranteedlosses , no variation to the contract price shall be made , for transformers where thetotal losses between 105% to 110% of the total evaluated guaranteed losses , thecontract price shall be reduced by the cost of the difference between the total losses andthe 105% of the total evaluated guaranteed losses according to the following values.

Iron losses 1800 USD per kW.Copper losses 600 USD per kW.For any transformer with total losses less than 100% of the guaranteed losses , no

variation to the contract price shall be made.

9- Test9-1 Inspection:

The material shall be subjected to inspection and test by our inspectors orinternational inspector at any time during manufacture.

The manufacture shall provide all inspection facilities for the saidinspection and inspection shall be made at the place of manufacture or atinternational testing facilities.

The inspector shall have the right of rejecting any portion of the material atany time during manufacture if it dose not meet with the requirements of thisspecification in all particulars . He shall have the right of overseeing the packingand shipping of all material to be supplied.

9-2 Test at manufacture work:

Test at manufacturroutine tests.

a-Type testsThe 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 impulse-voltage withstand test clause test

45 of IEC 76/1967.3- Cost of these tests to be borne by the manufacturer.

b- Routine testsEach transformer shall be subjected to all the routine tests specified in

section twelve of IEC 76/1967.

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 tests.

- 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 factory shall be witnessed by anauthorized representative of our (EC).

The cost of travelling & accommodation of required authorized engineersto witness the test at the place of manufacture for required days , to be ontenderer account.

10- Drawing , Instruction Book And Litreature.

10-1 document to be submitted with the tender:The following documents shall be submitted by the tenderer along with his

tender:-a- full and technical specification of transformer including schedule

A&B of guaranteed technical particulars.b- An outline drawing showing the plan , front and side elevation of

the transformers , dimensions , terminals , equipment , and all accessories ofthe 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.

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 equipments.c- 24 copies of instruction for erection of the equipment.d- 24 copies of spare parts list with catalogue number.

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 dimension of each type of the

required transformers to be as small as possible the following table is indicativeas a maximum for each single dimension:-

Table of Dimension

TransformerKVA

LengthMM

WidthMM

HeightMM

100 1220 600 1200250 1230 700 1300400 1400 1000 1400630 1500 1200 16001000 1500 1300 1800

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 thesame before commencing manufacture.

Failure to comply with this clause shall make the equipment or parts orparts there of liable to rejection.

11- PackingThe supplier will pack or protect the goods in the most appropriate manner.

He will be responsible for any loss or damage arising from carelesspacking or protection up to the place of final destination after completion of theinspection 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 thetime of erection shall be conspicuously tagged.

The method of packing shall be such as to protect all the items againstexcessive corrosion of dampness, and shall afford adequate protection againstbreakage or other injury, or loss due to breakage of cases or crates from the timethe items leaves the factory until finally installed at the substation during whichtime, the apparatus will travel by rail by a long sea voyage again by rail or truckto the site of the substation. The equipment will also undoubtedly stand onwharves and in the open during and in between periods of transportation and willthereby be exposed to heavy rain, hot sun, humid climate and sudden changes oftemperature.

Owing to the numerous handlings, the containers should be very strongalso extra ordinary care should be given to the packing of the equipment andespecially the items having insulating material to prevent the injury due tomoisture, from sources external to the packing or from excessive condensationwith the packing.

12- Spare parts and special tools for each rating

12-1 Spare parts:1- H.T / L.T winding. 3%2- 10%3- 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 piece for each item are required.12-2 Special tools:

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

SCHEDULE ((A))SCHEDULE OF THE GUARANTEED PERFORMANCE AND

OTHER TECHNICAL PARTICULARS(TO BE COMPLETED BY THE TENDERER)

Unit 100 250 400 630 1000KVA KVA KVA KVA KVATr. 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 ( valid clause 5 (1) ONAN rating-(KVA)5- Rated temperature rise ( C )a- Oil by thermometer.b- Winding by resistance6- Hottest spot temperature-(c).7- No-load voltage ratio at normal tap & vector relationship>8- Exciting current referred to H.V. and 50 c/s and at . . (Amps)a- 90% rated voltage.b- 100% rated voltage.c- 110% rated voltage.9- Power factor of exciting current at100% rated voltage and 50 HZ . . (%).

10- Iron losses at 50 HZ and at .. (kW).a- 90% rated voltage.b- 100% rated voltage.c- 110% rated voltage.11- Copper losses at full load (O.N.rating) and at 75 C (kW)12- Total losses .. (kW).13- Resistance voltage at full load and at 75 C (%).14- Reactance voltage at full load and at 75 C . . . (%)15- Impedance voltage at full load 75 C . . .a- At normal tap.b- At highest tap.c- At lowest tap.

16- Resistance of H.V. winding per phase at 20 C -(ohms).17- Resistance of L.V. winding per phase at 20 C -(ohms).18- regulation at full load at 75 C

a- 1.0 power factor.b- 0.8 P,F lagging.

19- Efficiency at 75 C -(%)a- 100% loadb- 75% load

c- 50% loadd- 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- yoke22- Maximum flux density at 110% voltage and frequency and at normal voltage and

frequency and at normal ratioa-Coreb- Yoke

23- Insulation ofa-Core boltsb- Core bolts washerc-Side platesd- Core laminations

24- Current destiny in windings Amps/sq.cm.a- H.V. windingb- L.V. winding

25- Insulation on copper26- insulation strength of winding.

a- Impulse full wave -(kV)( I ) H.V.(I I ) L.V.

b- Impulse chopped wave -(kV)( I ) H.V.(I I ) 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)

28- Type of core29- Tap changer

a- Manufacturerb- Typec- Step of one tap in per cent of rated voltage

30- Thickness of transformer tank (mm)a-Sidesb-Bottomc-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 -(IMP.Gall)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.

SCHEDULE B

OIL CHABACTERISTICS TABLE (TO BE COMPLETED BY THE TENDERER)NO. DESCRIPTION UNIT SPECIFICATIONS1. MAKER S NAME2. REFERENCE NAME OF OIL3. SLUDGE VALUE 0%4. FLASH POINT (CLOSED) C5. POUR POINT C6. VISCOSITY AT 21 CST7. ELECTRIC STRENGTH(BREAKDOWN KV VOLTAGE)

8. ACIDITY(NEUTRALIZATION VALUE)-TOTAL mg/KOH/g-INORGANIC

9. SAPONIFICATION VALUE mg/KOH/g10. COPPER DISCELERATION

11. CRACKLE12. SPECIFIC GRAVITY13. SULFER CONTENT14. DIELECTRIC DISSIP ATION FACTOR (tend)

annex (a) technical specifications for distribution

Documents