PART 1 - GENERAL
1.01 DESCRIPTION
A. This section cover the manufacturer, furnish, install and test all equipment, accessories and materials required for the installation of cast resin distribution transformer in accordance with specifications and drawings. Any material or equipment necessary for the proper operation not specified or described herein shall be deemed part of the specifications.
1.02 APPLICABLE CODES AND STANDARDS
A. The work shall be carried out in accordance with this specification, the contract drawings and the standards listed hereunder.
The following codes and standards provide an acceptable level of quality for materials and products:
1. SASO Saudi Arabian Standards Organization.
2. IEC 60076-1 Power transformers
to 60076-5
3. IEC 60726 Dry type power transformers
4. IEC 60905 Loading guide for dry-type power transformers.
5. CENELEC Harmonisation Documents:
- HD 464 S1: 1988 + / A2: 1991 + / A3: 1992 for dry-type power transformers
- HD 538-1 S1: 1992 for three-phase dry-type distribution transformers 50 Hz, from 100 to 2500 KVA with highest voltage for equipment not exceeds 24 KV.
1.03 QUALITY ASSURANCE
A. All materials and products shall be new, sound and uniform in quality, size, shape, color and texture and shall be free from defects.
B. The contractor shall be responsible for ensuring that the required standards of quality control as mentioned in relative sections are maintained for the proposed transformer.
C. If requested by the client, the supplier shall provide proof of application of a quality procedure complying with standards. This means:
1. use of a quality manual approved and signed by a management representative,
2. regular updating of this manual so that it reflects the most recent applicable quality control procedures,
3. ISO 9002 certification.
D. The manufacturer must have a sound experience in the field of transformers for not less than ten years, and should have a presentable reference list of the already supplied equipment of the same type and same make and that this equipment has been in satisfactory operation in Kingdom of Saudi Arabia for at least three years.
1.04 SUBMITTAL
A. Shop Drawings and Manufacturer's Data:
The contractor shall submit to the client/client representative for review, detailed dimensioned shop drawings and manufacturer's literature where deviations from the contract drawings or specification exist. Shop drawings and/or data sheets shall be based on information stated in the specifications and as shown on the contract drawings and shall show all pertinent deviations and data for the fabrication and complete installation.
Manufacturer's data sheets shall be submitted indicating the necessary installation dimensions, weights, materials and performance information. The above information may be provided by standard catalogue sheets marked to indicate the specific items provided.
B. Operation and Maintenance Instructions:
The contractor shall furnish data covering model, type and serial numbers, capacities, maintenance and operation of each major item of equipment or apparatus in accordance with the requirements of the contract documents. Operating instructions shall cover all phases of control.
C. Test Reports:
The contractor shall submit test reports to the client/client representative for review.
D. Recommended Spare Parts List:
The contractor shall submit recommended spare parts list to the client/client representative for review.
E. As Built Drawings:
The contractor shall submit the as built drawings to the client/client representative for review and approval.
1.05 COORDINATION
A. The contractor shall be held responsible for the proper coordination of all phases of the work under this contract.
B. It shall be the responsibility of the contractor to coordinate the work and equipment as specified herein with work to be performed and equipment to be furnished under other sections of the specifications in order to assure a complete and satisfactory installation.
1.06 PRODUCT DELIVERY, STORAGE AND HANDLING
A. Deliver, store, protect and handle products to site as per manufacturer’s instructions.
B. Store transformers in clean and dry space. Inspect for damage. Maintain factory wrapping or provide an additional heavy canvas or heavy plastic cover to protect units from dirt, water, construction debris and traffic.
C. Lift only with lugs provided for the purpose. Handle carfully to avoid damage to transformers internal components, enclosure and finish.
PART 2 - PRODUCTION
2.01 GENERAL
A. The following specifications apply to three-phase transformers of cast resin type, class F insulation system with natural (AN) cooling for indoor installation, destined for use in three-phase MV/LV distribution systems.
B. If required, forced cooling (AF) can be used to increase the rated power up to 40%.
2.02 GENERAL REQUIREMENTS
A. General
1. The transformers shall be of climatic class C2 and of environmental class E2 as defined in appendix B of HD 464 S1: 1988 / A2: 1991. C2 and E2 classes shall be indicated on the rating plate.
2. The transformers shall be of fire behaviour class F1 as defined in article B3 of CENELEC HD 464 S1: 1988 / A2: 1991. F1 class shall be indicated on the rating plate.
B. Magnetic Core
1. This shall be made from laminations of grain oriented silicon steel, insulated with mineral oxide and shall be protected against corrosion with a coat of varnish.
C. LV Windings
1. These shall be made from aluminium or copper foil (according to the manufacturer's preference) with class F interlayer insulation by encapsulation (impregnation) with synthetic alkyd resin or equivalent.
2. At least the upper part of the LV coils shall be covered with a coat of epoxy resin or equivalent and the foil shall be protected everywhere with an insulation material even in the air ducts.
D. MV Windings
1. These shall be independent of the LV windings and shall be made of aluminium or copper wire or foil (according to the manufacturer's preference) with class F insulation.
2. The MV windings shall be vacuum cast in a class F fireproof epoxy resin casting system composed of:
- An epoxy resin
- An anhydride hardener with a flexibilising additive
- A flame-retardant filler.
3. The flame-retardant filler shall be thoroughly mixed with the resin and hardener. It shall be composed of trihydrated alumna powder (or aluminium hydroxide) or other flame-retardant products to be specified, either mixed with silica or not.
4. The casting system shall be of class F.
E. MV Connections
1. The MV connections shall be made from above on the top of the connection bars. Each bar shall be drilled with a 13-mm hole ready for connection of cable lugs on terminal plates.
2. The MV connection bars shall be in rigid copper bars protected by heat shrinkable tubing.
3. MV connections in cables are not allowed.
4. The MV connections shall be copper.
F. LV Connections
1. The LV connections shall be made from above onto bars located at the top of the coils on the opposite side to the MV connections.
2. Connection of the LV neutral shall be directly made to the LV terminals between the LV phase bars.
3. The LV connection bars shall be copper or tinned aluminium (according to preference of the manufacturer).
G. MV Tapping
1. The tapping which act on the highest voltage adapting the transformer to the real supply voltage value, shall be off-circuit bolted links.
2. Tapping with connection cables is not allowed.
3. These bolted links shall be attached to the MV coils.
2.03 METAL ENCLOSURE
A. If mentioned in the documents, the transformers shall be equipped with a metal enclosure for indoor installation comprising an integral IP 31 (except the base which may be IP 21) metal enclosure with:
1. An anti-corrosion protection in the manufacturer's standard colour.
2. Lifting lugs enabling the transformer and enclosure assembly to be handled.
3. A bolted access panel on the enclosure front to allow access to the MV connections and to the tapping. This shall be fitted with handles; it shall have one "Danger Electricity" warning label (T 10 warning), a rating plate and a visible braid for earthling.
4. Blanked off holes for fitting key locks on the bolted access panel to enable it to be locked.
5. 2 UN-drilled gland plates on the roof: one on the MV side, one on the LV side (drilling and cable gland not supplied).
6. 1 plate at the right MV side on the bottom of the enclosure for the MV cables for connections from the bottom.
2.04 ACCESSORIES AND STANDARD EQUIPMENT
A. The transformers shall be equipped with:
1. 4 flat bi-directional rollers
2. 2 lifting lugs
3. Haulage holes on the under base
4. 2 earthling terminals
5. 1 rating plate
6. 1 "Danger Electricity" warning label
7. 1 routine tests certificate
8. 1 instruction manual for installation, commissioning and maintenance in English.
B. Thermal protection
1. The transformers shall be equipped with a thermal protection device, which shall comprise:
- 2 sets of 3 PTC sensors, one sensor for "Alarm 1", one for "Alarm 2" per phase, installed in the coils of the transformer. They shall be placed in a tube to enable them to be replaced when ever necessary.
- An electronic converter with two independent monitoring circuits equipped with a changeover switch, one for "Alarm 1" and the other for "Alarm 2". The position of the relays shall be indicated by different coloured indicator lights. A third indicator light shall indicate the presence of voltage.
2. The three indicator lights shall be on the front of the converter. The electronic converter shall be installed away from the transformer.
3. A plug-in terminal block shall be provided for connection of the PTC sensors to the electronic converter.
4. The PTC sensors shall be supplied assembled and wired to the terminal block fixed on the upper part of the transformer. The converter shall be supplied loose with the transformer, packaged complete with its wiring diagram.
2.05 ROUTINE AND TYPE TESTS
A. Routine Tests
The following tests shall be carried out on all the transformers after the manufactu¬ring, enabling an official test certificate to be produced for each one:
1. Measurement of windings resistance.
2. Measurement of the transformation ratio and vector group
3. Measurement of impedance voltage and load loss
4. Measurement of no load loss and no load current
5. Applied voltage dielectric test
6. Induced voltage dielectric test
(All these tests shall be in accordance with Harmonisation Document HD 464 S1: 1988, the IEC 60726 and IEC 60076-1 to 60076-5 standards).
C. Type Tests and Special Tests
The following tests may be requested (if mentioned in the documents):
1. Temperature rise test carried out in accordance with the simulated loading method as defined by the IEC 60726 standard.
2. Lightning impulse test.
3. Short circuit test.
4. Noise level measurements in accordance with IEC 60551.
5. Measurement of partial discharges.
For measurement of the partial discharges, the acceptance criterion shall be:
- Partial discharges less than or equal to 10 pC at 1.10 Um.
If Um > 1.25 Un (Un = rated voltage, Um = system highest voltage), then the 10 pC are guaranteed at 1.375 Un.
(All these tests shall be in accordance with Harmonisation Document HD 464 S1: 1988, the IEC 60726 and IEC 60076-1 to 60076-5 standards).
6. The climate and environmental tests shall be performed in accordance with appendix ZA and ZB of CENELEC HD 464 S1: 1988 / A3: 1992.
7. The fire behaviour test shall be performed in accordance with appendix ZC of CENELEC HD 464 S1: 1988 / A3: 1992.
D. The manufacturer shall produce a test report from an official laboratory on a transformer of the same design as those produced.
Transformer Technical Data
For each requested transformer, the supplier shall give the following data :
Rated power As required KVA
Cooling AN or AF (as mentioned in the documents)
Rated frequency 60 Hz
Primary voltage 13.8 KV
Rated primary insulation level 17.5 KV
Power frequency withstand Voltage(rms) 38 KV
Basic Insulation Level (BIL) or impulse withstand voltage (peak) 95 KV
Off-circuit tapping +/- 2.5 %
Secondary voltage at no load between phases As required V
phase to neutral As required V
Vector group Dyn11
No load losses W
Load losses at 75° C W
Load losses at 120° C W
Rated impedance voltage at 120° C %
Acoustic power Lw(A) dB(A)
Acoustic pressure at 1 metre Lp(A) dB(A)
Maximum ambient temperature °C
Daily average ambient temperature °C
Yearly average ambient temperature °C
Maximum altitude m
MV winding temperature class F
LV winding temperature class F
Temperature of insulation system 155 °C
Climatic classification (HD 464 S1) C2
Environmental classification (HD 464 S1) E2
Fire behaviour classification (HD 464 S1) F1
Enclosure YES NO
Protection degree IP 31
Length mm
Width mm
Height mm
Total weight kg
Measurement circuit supply voltage for the thermal protection electronic
Converter DC AC V
PART 3 - EXECUTION
3.01 WORKMANSHIP
A. Materials, products and equipment furnished by the contractor, shall be installed and all work shall be performed in a first-class workmanship manner, in conformity with the best trade practices and the printed directions of the applicable manufacturers; by skilled workers equipped to produce satisfactory results; in a safe, substantial manner so as to avoid undue stresses, rigid enough to prevent undue movement, so as to present a neat, orderly appearance and to facilitate operating, servicing, maintenance and repairing.
3.02 FOUNDATIONS AND SUPPORTS
A. The contractor shall provide concrete pedestals, anchor bolts, hangers, channels, saddles, etc., for installation of equipment and apparatus shown on the drawings and specified in the various sections.
3.03 EQUIPMENT ERECTION
A. All electrical equipment shall be installed in accordance with the manufacturer's recommendations, good electrical engineering practice, and the relevant drawings and specifications.
B. All metal surfaces to be bolted shall be thoroughly cleaned before assembly. The connections shall be tightened with manual torque wrenches to the manufacturer's erection instructions.
3.04 EQUIPMENT TESTING AND COMMISSIONING
A. After the installation is complete and properly adjusted, the contractor shall conduct operating tests. The various equipment and systems shall be demonstrated to operate in accordance with the requirements of the contract documents. Tests shall be performed in the presence of the client/client representative. The contractor shall provide electric power, instruments and personnel necessary for performing the various tests.
B. The testing of all electrical equipment shall include, but not be limited to, the items below. This shall be in addition to testing specified elsewhere in this specification.
1. General equipment check.
2. Field wiring and ground system verification.
3. Equipment adjustment.
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