Download 7. Electrical tests - Schneider Electric

Specification for Tender
582753327
General Specification for three-phase oilimmersed HV-LV distribution
transformers 100 to 2500 kVA
Last update : 2017-05-05
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Specification for Tender
582753327
Table of contents:
1. Scope…………………………………………………………………………………………..........
p. 3
2. Standards……………………………………………………………………………………...........
p. 3
3. Description……………………………………………………………………………………........
p. 3
3.1 Magnetic core…………………………………………………………………………………........
p. 3
3.2 LV windings……………………………………………………………………………………......
p. 3
3.3 HV windings.....................................................................................................................................
p. 3
3.4 HV connections……………………………………………………………………………….........
p. 3
3.5 LV connections……………………………………………………………………………….........
p. 3
3.6 HV tapping……………………………………………………………………………………........
p. 4
4. Accessories and standard equipment………………………………………………………….....
p. 4
5. Protection……………………………………………………………………………………..........
p. 4
6. Main characteristics of construction…………………………………………………………......
p. 4
6.1 Tank…………………………………………………………………………………………….......
p. 4
6.2 Dielectric and component material……………………………………………………………........
p. 4
6.3 Gaskets ………………………………………………………………………………………….....
p. 4
6.4 Protection against corrosion……………………………………………………………………......
p. 5
7. Electrical tests…………………………………………………………………………………. .....
p. 5
7.1 Routine tests……………………………………………………………………………………......
p. 5
7.2 Type tests or special tests………………………………………………………………..................
p. 6
7.3 Caractéristiques techniques ………………………………………………………………………..
p. 7
Last update : 2017-05-05
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Specification for Tender
582753327
1. Scope
Three-phase oil-immersed transformers, hermetically sealed with integral filling, insulation system with oil
natural air natural (ONAN) cooling for indoor or outdoor installation, destined for use in three-phase HV/LV
distribution systems .
2. Standards
These transformers will be in compliance with the following standards :
IEC 60076-1 à 60076-5
- CENELEC Harmonisation Documents :
- HD 398-1 : 1980 + A3 1986 for power transformers
- HD 428-1 S1 : 1992 for three-phase oil-immersed type distribution transformers 50 Hz, from 100 to 2500
kVA with highest voltage for equipment not exceeding 24 kV.
- IEC 354 edition dated 1991- Loading Guide for oil-immersed type power transformers.
These transformers will be manufactured in accordance with :
- a quality system in conformity with ISO 9001
- an environmental management system in conformity with ISO 14001, both certified by an official
independent organisation.
3. Description
3.1 magnetic core
This will be made from laminations of grain oriented silicon steel, insulated with mineral oxide; the method
of cutting and stacking will be "step lap", so as to optimise the level of no-load losses.
3.2 LV windings
These will be made from copper profile wire or aluminium or copper foil (according to the manufacturer's
preference ) .
3.3 HV windings
These will be made of copper profile wire or aluminium or copper round wire (according to the
manufacturer's preference).
3.4 HV connections
The standard HV connections will use porcelain bushings on the top of the transformer.
Fixed HV plug-in bushings 24 kV 250A, with HV mobile plug-in bushings - straight or elbow according to
the orientation of the incoming cables - may be provided as an option.
3.5 LV connections
The LV connections will be made using porcelain bushings up to 200 kVA, and flat-bars from 250 kVA
onwards.
LV porcelain bushings from 250 kVA are also available on request.
A LV air-insulated terminal cover may be provided as an option.
Last update : 2017-05-05
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Specification for Tender
582753327
3.6 HV tapping
The tapping which act on the highest voltage adapting the transformer to the real supply voltage value, will
be provided with an off-circuit tap-changer switch with a padlocking facility on the top cover of the
transformer.
4. Accessories and standard equipment
These transformers will be equipped with :
- 4 bi-directional flat rollers
- 2 lifting and untanking lugs
- 2 earthling terminals
- 1 filling plug
- 1 draining device
- 1 rating plate
- 1 routine test certificate
5. Protection
These transformers will be equipped in option with a protection relay , DGPT2 type, (strongly recommended
for powers higher than 400 kVA) including :
- 1 gas detector/flow level indicator with one contact (for gas discharge and drop in liquid level)
- 1 over-pressure contact (for internal pressure increase)
- 1 thermostat with 2 contacts for alarm and tripping (for internal temperature increase)
- 1 dial type thermometer without contact.
6. Main characteristics of construction
6.1 Tank
The tank of the transformer will be made with flexible cooling corrugations, in order to absorb the expansion
of the dielectric due to temperature variations.
The cover will be bolted on top of the tank.
The tank will be built in such a way as to avoid any water accumulation.
6.2 Dielectric and component material
The dielectric will be mineral oil, class I & II according to IEC 296.
The concentration in PCB (polychlorobiphenyl) has to be lower than the minimum detection rate of 2 ppm
(parts per million).
The components of the transformer such as insulation material, varnish, painting, etc. have to be new and
PCB-free.
The filling of the transformer will be made under vacuum, in order to guarantee the maximum preservation
of dielectric properties.
The live part of the transformer will be previously oven dried so as to remove all residual humidity.
6.3 Gaskets
All the gaskets (in general made of elastomer) have to be resistant against the action of the mineral oil, at the
working temperature.
Last update : 2017-05-05
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Specification for Tender
582753327
6.4 Protection against corrosion
The anticorrosion treatment of the tank and the cover will comprise :
- an external degreasing and rinsing
- a hot phosphating operation
- a powdering through application of a polyester resin with an electrostatic spray gun (minimum thickness 40
to 50 microns)
- final colour green grey RAL 7033
The main characteristics of the coating guarantee:
- a gloss of 30 to 60 % for an angle of 60° (measured according to ASTM-D523)
- a salt spray resistance of 1000 hours (measured according to ASTM-B117)
- a UV resistance without losses more than 10% gloss according to the RAL scale 1 (measured according to
NFT 30-057, over a 3 months period)
- an adherence of between 0 and 1 (measured according to ASTM-D3359)
7. Electrical tests
7.1 Routine tests
These tests will be carried out on all the transformers after the manufacturing, enabling an official test
certificate to be produced for each one :
- applied voltage dielectric test
- induced voltage dielectric test
- measurement of no load loss and no load current
- measurement of windings resistance
- measurement of impedance voltage and load loss
- measurement of the transformation ratio and vector group
(All these tests are defined in the IEC 60076-1 to 60076-5 standards).
7.2 type tests or special tests
These tests can be requested as option, but are subject to prior agreement of the supplier :
- temperature rise test
- lightning impulse test
- measurement of partial discharges.
- short circuit test (implemented in an approved laboratory)
- noise level measurements in accordance with IEC 551.
(All these tests are defined in the IEC 60076-1 to 60076-5 standards).
Last update : 2017-05-05
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Specification for Tender
582753327
7.3 Technical Data
For each requested transformer, the supplier will give the following data :
Rated power.....................................................................................................
kVA
Cooling ............................................................................................................. ONAN
Quantity............................................................................................................
Rated frequency...............................................................................................
Hz
Rated primary voltage ......................................................................................
kV
Rated primary insulation level ..........................................................................
kV
Applied voltage to industrial frequency (50 Hz/1 min) ......................................
kV
Basic Insulation Level (BIL) or impulse (1.2/50 µ) ............................................
kV
Off-circuit tapping .............................................................................................
%
Secondary voltage at no load between phases ............................................
V
phase to neutral.............................................
V
Rated secondary insulation level .....................................................................
kV
Applied secondary voltage to industrial frequency ...........................................
kV
Vector group ....................................................................................................
No load losses .................................................................................................
W
Load losses at 75° C ........................................................................................
W
Rated impedance voltage at 75° C ..................................................................
%
Acoustic power Lw(A) ...................................................................................... dB(A)
Acoustic pressure at 0.3 metre Lp(A) ............................................................... dB(A)
Maximum ambient temperature .......................................................................
Daily average ambient temperature .................................................................
Yearly average ambient temperature ...............................................................
Maximum altitude .............................................................................................
°C
°C
°C
m
Temperature rise of windings .........................................................................
Temperature rise of dielectric .........................................................................
K
K
Length ..............................................................................................................
Width ................................................................................................................
Height ..............................................................................................................
Total weight......................................................................................................
Dielectric weight ...............................................................................................
mm
mm
mm
kg
kg
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