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
Altitude above sea level:
Ambient Temperature:
Maximum outdoor - shade
Minimum outdoor
Maximum outdoor daily average
Maximum outdoor yearly average
Maximum ground at depth 1 m
Maximum Black Body (black objects in direct sun)
Relative Humidity:
Maximum
Minimum
Yearly Average
Maximum wind velocity:
Rainfall per year:
Maximum
Minimum
Maximum in one day
Yearly Average
Description
Up to 1,000m above sea-level
+55 °C for 6 hours a day
-10 °C
+40 °C
+30 °C
+35 C
+80 C
92 %
12 %
44 %
140 kilometre per hour
500 mm
50 mm
65 mm
150 mm
Subject to sand storms and
Atmosphere:
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;
Voltage
Description
Nominal Voltage
Highest System Voltage
Number of Phases
Frequency
Neutral Point
3 Phase Short Circuit Level
Duration of Short Circuit
Insulation Levels:
Impulse
Power Frequency 1 min
11 kV
11 kV
12 kV
3
50 Hz
See Note below
25 kA
1 sec
400 V
400/230 V
416 V
3
50 Hz
Directly Earthed
10 kA
-
75 kV
28 kV
3 kV
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
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.
#
1.
2.
Description
Programme for production and
testing
Detailed dimension drawings for
all components, general
arrangement drawings showing
detailed component layout and
overall assembly drawings
Delivery Time
Objective
Within one month
Approval
of contract award
No. of
Copies
3
#
3.
4.
Description
Progress reports
6.
Notification of inspection and
tests
8.
9.
10.
11.
12.
13.
Objective
No. of
Copies
Detailed drawing of mounting
arrangements
Certificates of compliance and
certificates of origin
5.
7.
Delivery Time
List of tests and description of
the tests to be performed
Test reports for all type tests,
routine tests and special tests
and inspection reports
Technical Data Schedule with
approved revisions if any
Detailed schematic and wiring
drawings for all components
General description of the
equipment and all components
including brochures
Installation and commissioning
instructions
Operation and maintenance
instructions manual
At agreed
intervals
Monitoring
Review and
One month before necessary
action
inspection /
testing
Approval
Immediately after
tests/inspection
are completed
Approval
3
3
3
5
5
5
One month before
Approval
delivery
5
5
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
Rated Voltage
10.1
Requirement
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
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.
-
10.2
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.
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:
11.
11.1

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.
Materials and Construction
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:
11.3

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.
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:











11.7
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
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:












13.2
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.
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

13.3
Tank Vacuum Test

Measurement of Harmonic Level in no load condition

Oil Analysis
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
15.
-
Table of primary voltages at the 5 tapping positions
-
Employer’s name
Connection diagram
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
1
2
International standards transformer complies with
Nominal frequency
3
Rated Power
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
11
Hz
kVA
Number of steps
± steps
Tapping range
±%
Current
kA
Duration
s
12
Rated short circuit current
and withstanding duration
13
Impedance measured at 75 C and center tap
%
14
X/R ratio
25 % overload
15
Duration of overload
50% overload
C
minutes
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
19
20
21
22
23
24
Magnetic flux density
Core Losses
Winding losses
No load current
Regulation: full load, PF=1
full load, PF=0.85
Manufacturer
Silicon steel
Type and grade
C
Tesla
W
W
A
%
%
Data
#
Description
Operating flux density
Losses kW/kg at operating flux density
Manufacturer’s data sheet supplied
#
Description
25
Unit
Tesla
kW/kg
Yes/No
Data
Unit
Data
Manufacturer/Supplier and type
Conductor for HV winding
Conductor Material
Shape and cross sectional area
26
Manufacturer/Supplier and type
Conductor for LV winding
Conductor Material
Shape and cross sectional area
27
Manufacturer/Supplier
HV Bushing
Type and grade
Bushing catalogue number
28
Manufacturer/Supplier
LV Bushing
Type and grade
Bushing catalogue number
29
30
Bushing basic impulse
level
Bushing power frequency
withstand voltage
31
HV Bushing
kV
HV Bushing
kV
LV Bushing
kV
Type and metal used in HV terminal
Terminals
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
Manufacturer/supplier
Tap changer
36
37
Catalogue details attached
Yes/No
Manufacturers data sheet attached
Yes/No
Can tap changer switch be locked
Tank material
Tank Fabrication
Thickness of the metal sheet
Tank Dimensions
Painting method details attached
Width
Height
Transformer weights
Depth
Weight of core and windings
38
39
Type
Yes/No
Yes/No
mm
mm
mm
kg
Weight of tank
kg
Weight of oil at 20 C
Total weight of transformer, ready for
service
Shipping weight of transformer
Signature: ______________
Company Seal
kg
kg
kg
Date:
1.2 Technical Data Schedule for 250 kVA Distribution Transformer
#
Description
Unit
1
2
International standards transformer complies with
Nominal frequency
3
Rated Power
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
11
Hz
kVA
Number of steps
± steps
Tapping range
±%
Current
kA
Duration
s
12
Rated short circuit current
and withstanding duration
13
Impedance measured at 75 C and center tap
%
14
X/R ratio
25 % overload
15
Duration of overload
50% overload
C
minutes
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
19
20
21
22
23
24
Magnetic flux density
Core Losses
Winding losses
No load current
Regulation: full load, PF=1
full load, PF=0.85
Manufacturer
Type and grade
Operating flux density
Silicon steel
Losses kW/kg at operating flux density
Manufacturer’s data sheet supplied
C
Tesla
W
W
A
%
%
Tesla
kW/kg
Yes/No
Data
#
Description
25
Unit
Manufacturer/Supplier and type
Conductor for HV winding
Conductor Material
Shape and cross sectional area
26
Manufacturer/Supplier and type
Conductor for LV winding
Conductor Material
Shape and cross sectional area
27
Manufacturer/Supplier
HV Bushing
Type and grade
Bushing catalogue number
28
Manufacturer/Supplier
LV Bushing
Type and grade
Bushing catalogue number
29
30
Bushing basic impulse
level
Bushing power frequency
withstand voltage
31
HV Bushing
kV
HV Bushing
kV
LV Bushing
kV
Type and metal used in HV terminal
Terminals
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
Manufacturer/supplier
Tap changer
36
37
Type
Catalogue details attached
Yes/No
Manufacturers data sheet attached
Yes/No
Can tap changer switch be locked
Tank material
Tank Fabrication
38
Tank Dimensions
39
Transformer weights
Yes/No
Thickness of the metal sheet
Painting method details attached
Width
Height
Depth
Weight of core and windings
Weight of tank
Weight of oil at 20 C
Total weight of transformer, ready for
service
Yes/No
mm
mm
mm
kg
kg
kg
kg
Data
Shipping weight of transformer
kg
Signature: ___________________ Company Seal
1.3 Technical Data Schedule for 400 kVA Distribution Transformer
#
Description
Unit
1
2
International standards transformer complies with
Nominal frequency
3
Rated Power
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
11
Hz
kVA
Number of steps
± steps
Tapping range
±%
Current
kA
Duration
s
12
Rated short circuit current
and withstanding duration
13
Impedance measured at 75 C and center tap
%
14
X/R ratio
25 % overload
15
Duration of overload
50% overload
C
minutes
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
19
20
21
22
23
24
Magnetic flux density
Core Losses
Winding losses
No load current
Regulation: full load, PF=1
full load, PF=0.85
Manufacturer
Type and grade
Silicon steel
Operating flux density
Losses kW/kg at operating flux density
C
Tesla
W
W
A
%
%
Tesla
kW/kg
Data
#
Description
Manufacturer’s data sheet supplied
#
Description
25
Unit
Yes/No
Data
Unit
Data
Manufacturer/Supplier and type
Conductor for HV winding
Conductor Material
Shape and cross sectional area
26
Manufacturer/Supplier and type
Conductor for LV winding
Conductor Material
Shape and cross sectional area
27
Manufacturer/Supplier
HV Bushing
Type and grade
Bushing catalogue number
28
Manufacturer/Supplier
LV Bushing
Type and grade
Bushing catalogue number
29
30
Bushing basic impulse
level
Bushing power frequency
withstand voltage
31
HV Bushing
kV
HV Bushing
kV
LV Bushing
kV
Type and metal used in HV terminal
Terminals
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
Manufacturer/supplier
Tap changer
36
37
Type
Catalogue details attached
Yes/No
Manufacturers data sheet attached
Yes/No
Can tap changer switch be locked
Tank material
Tank Fabrication
Thickness of the metal sheet
Painting method details attached
Width
38
Tank Dimensions
39
Transformer weights
Yes/No
Height
Depth
Yes/No
mm
mm
mm
Weight of core and windings
kg
Weight of tank
kg
Weight of oil at 20 C
Total weight of transformer, ready for
service
Shipping weight of transformer
kg
kg
kg
Signature: ___________________ Company Seal
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
2.2 Schedule of Non Compliance - 250 kVA Distribution Transformer
Non Compliance
Claus
e No
2.3 Schedule of Non Compliance - 400 kVA Distribution Transformer
Clause No
Non Compliance
Signature: ___________________ Company Seal
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
3.2 Schedule of Test Certificates for 250 kVA Distribution Transformer
Clause No
Type Test Certificate and Routine Test Report
3.3 Schedule of Test Certificates for 400 kVA Distribution Transformer
Clause No
Type Test Certificate and Routine Test Report
Signature: ________________________
Date: ______________________
Company Seal
ELECTRICITY COMMISSION
PLANNING AND STUDY DEP
BAGHDAD, REPUBLIC OF IRAQ
SPECIFICATION No.
D-26
DISTRIBUTION TRANSFORMER
kV
REVISION
YEAR 2001
DISTRIBUTION TRANSFORMERS
1- SCOPE OF THE TENDER :
Tenderer are invited for the design , manufacture , testing and supply of a
11000/416 volt,oil immersed copper winding outdoor type (Directly under the sun)
transformers to be supplied complete with all necessary fittings , accessories offload tap changer , insulating oil and spare parts . . . etc.
The transformer is to be hermetically sealed (without conservator tank)bolted cover
with 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 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 Sun Temperature:
Black objects under direct sunshine attain a temperature of 80 C .
2-1-3 Air humidity :
Maximum
Minimum
Yearly average
92% at 40 C
12%
44%
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:
2-3-1 High voltage side:Nominal voltage
Short circuit level
Frequency
Highest system voltage
system
11000 Volts
25 KA at 11000 volts
50 HZ.
12000 volts
3- phase,3-wire with neutral isolated but
provision is made for earthling through an
earthling resistance of 21.1 ohms to limit
the earth fault current to 300 Amp.
2-3-2 Low voltage side:Nominal voltage: 416/240 volts s
system
phase,4-wire
earthed.
neutral
solidly
Short circuit level
According to the short circuit level of
H.T side and the rated power of the
transformer
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 period
expires earlier.
3- system composition
The transformer shall operate in distribution systems where most of the net work
is overhead lines and comprising partly underground cable.
4- TECHNICAL SPECIFICATION
The transformers shall be copper winding. Hermetically sealed of the blolted cover and
should 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 by
resistance.
Off circuit tapings . . . . . . five tapping for 2.5% - 5% on the H.T winding for off
circuit operation externally. The machine must be of
the robust and definite position type with a click
indicating position arrived during tap changing.
System Highest Voltage . . H.V side 12 kV
Terminal arrangement of transformers:The 11 kV side terminal is to be a clamp type with eyebolt and nut suitable for
conductors up to 150 mm2 copper.
The low voltage terminal are to be flat bar type with holes suitable for
compression type thimble the sizes of L.V side:
For 100 KVA transformer 4x1x70 mm2 copper.
For 250 KVA transformer 6x1x195+1 70 mm2 copper
For 400KVA transformer 7x1x150 mm2 copper
For 630 KVA transformer 11x1x240 mm2 copper
For 1000 KVA transformer 14x1x240 mm2 copper
Terminal arrangement of outdoors transformers must be brown colored bushing
insulator mounted on the top cover of transformer for both H.T. and L.T, with arcing
horn on H.T.bushing for outdoor transformer only. Neutral bushing should
distinguished 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- painting
A primary coat shall be applied immediately after cleaning all ungalvanized
metallic parts thoroughly. An oil and weather resistant type second coat shall then
be applied and the transformer finished in aluminum paint.
7- insulating oil
The transformer is to be shipped with first filling of oil which shall be SHELL
DIALA (B).
8- 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 variation to the contract price 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 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- 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 dose 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 work:
Test at manufactur
routine tests.
a-Type tests
The type test prescribed shall be carried out on one unit of each capacity
1Test of temperature rise clause 41 of IEC 76/1967.
2Full wave impulse-voltage withstand test clause test
45 of IEC 76/1967.
3Cost 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.
-
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 an
authorized representative of our (EC).
The cost of travelling & accommodation of required authorized engineers
to witness the test at the place of manufacture for required days , to be on
tenderer account.
10- Drawing , Instruction Book And Litreature.
10-1 document to be submitted with the tender:
ab-
cdef-
The following documents shall be submitted by the tenderer along with his
tender:full and technical specification of transformer including schedule
A&B of guaranteed technical particulars.
An outline drawing showing the plan , front and side elevation of
the transformers , dimensions , terminals , equipment , and all accessories of
the transformers.
Catalogues of the manufacturer for transformers.
Valid ISO-9001 certificate of the manufacture r for transformers.
Test certificate for identical transformers.
Reference list of manufactured and exported transformers.
g-Incomplete tenders are liable to rejection.
10-2 Document to be furnished by the successful tenderer:
a-
bcd-
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:24 sets of prints on paper on all drawings.
24 copies of all instruction books and technical maintenance of the
transformer, OFF Load tap changing gear and other ancillary equipments.
24 copies of instruction for erection of the equipment.
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 indicative
as a maximum for each single dimension:-
Table of Dimension
Transformer
KVA
100
250
400
630
1000
Length
MM
1220
1230
1400
1500
1500
Width
MM
600
700
1000
1200
1300
Height
MM
1200
1300
1400
1600
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 the
same before commencing manufacture.
Failure to comply with this clause shall make the equipment or parts 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 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:
1234567-
H.T / L.T winding.
3%
10%
10%
Tap changer.
3%
Pressure relief valve.
2%
Oil level indicator.
10%
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 be
included in the scope of supply. An itemized list of special tools together with
prices shall be submitted with the tender.
SCHEDULE ((A))
SCHEDULE OF THE GUARANTEED PERFORMANCE AND
OTHER TECHNICAL PARTICULARS
(TO BE COMPLETED BY THE TENDERER)
Unit
1234-
100
KVA
Tr.
250
KVA
Tr.
400
KVA
Tr.
630
KVA
Tr.
1000
KVA
Tr.
Name of manufacturer.
Country of origin.
Standard on which performance data is based.
Continuous maximum rating for the specified.
Temperature rise and ambient temperature ( valid clause 5 (1) ONAN rating-(KVA)
5Rated temperature rise ( C )
aOil by thermometer.
bWinding by resistance
6Hottest spot temperature-(c).
7No-load voltage ratio at normal tap & vector relationship>
8Exciting current referred to H.V. and 50 c/s and at . . (Amps)
a90% rated voltage.
b100% rated voltage.
c110% rated voltage.
9Power 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% 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
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.
(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 core
29- Tap changer
a- Manufacturer
b- Type
c- Step of one tap in per cent of rated voltage
30- Thickness of transformer tank
a-Sides
b-Bottom
c-Corrugated radiators
(mm)
(i)
(ii)
(i)
(ii)
(iii)
defghij(i)
(ii)
(iii)
(iv)
k-
31- Weights and dimensions
a-Net weight of core
-(Kg)
b-Net weight of copper
-(Kg)
H.V.
L.V.
c-Net untanking weight of
Core
-(Kg)
Frame
-(Kg)
Coil
-(Kg)
Volume of insulating oil
-(IMP.Gall)
Net weight of insulating oil
-(Kg)
Total weight of transformer less oil
-(tons)
Weight of the largest shipping package
-(tons)
Crane lift for untanking core and coils
-(m)
Crane lift for removal of bushings
-(m)
Dimensions of transformer
-(m)
Under base to top most point
Under base to bushing mounting flanges
Overall breadth
Overall length
Overall shipping dimensions of tee largest package.
32- Noise level
..dB.
SCHEDULE B
8.
11.
12.
13.
14.
OIL CHABACTERISTICS TABLE (TO BE COMPLETED BY THE TENDERER)
NO. DESCRIPTION
UNIT
SPECIFICATIONS
1.
MAKER S NAME
2.
REFERENCE NAME OF OIL
3.
SLUDGE VALUE
0%
4.
FLASH POINT (CLOSED)
C
5.
POUR POINT
C
6.
VISCOSITY AT 21
CST
7.
ELECTRIC STRENGTH(BREAKDOWN
KV VOLTAGE)
ACIDITY(NEUTRALIZATION VALUE)
-TOTAL
mg/KOH/g
-INORGANIC
9. SAPONIFICATION VALUE
mg/KOH/g
10. COPPER DISCELERATION
CRACKLE
SPECIFIC GRAVITY
SULFER CONTENT
DIELECTRIC DISSIP ATION FACTOR (tend)