1.00.00 SCOPE AND GENERAL INFORMATION
1.01.00 In addition to the detailed scope and other requirements specified in Part-A, the intent of the specifications for various electrical equipments shall also cover the following scope:
1.02.00 Contractor shall be responsible for design and engineering of overall system/station, and all elements, systems, sub-systems, facilities, equipments, material, etc.. The Contractor shall submit design calculations, drawings, codes, codes of practices, construction drawings, etc. for Employer’s approval.
The basic design shall include, but not limited to, the following:
a) Development of general arrangement.
b) Development of detailed layout (plan & section/elevation) drawings.
c) Development of single line diagram with parameters of equipment and details of protection.
d) Protection and control philosophy and selection of protection, control and annunciation schemes.
e) Development of interlocking schemes.
f) Development of switchyard structure loading details.
g) Development of earthing system.
h) Development of direct stroke lightning protection system.
i) Insulation coordination of the EHV equipment.
j) Calculation of static and dynamic force load and selection of spacer spans and equipment terminal loading, (for outdoor switchyard)
k) Development of clearance diagrams.
l) Lighting design, Lux level calculations and conduit wiring diagram (for out door switchyard).
m) Development of power & control cable laying and termination schedules.
n) Relay setting calculations.
o) Development of erection key diagram with bill of material.
p) Foundation design and construction drawings.
q) Development of cable trench layout and sections, and construction drawings.
1.03.00 Contractor shall furnish detailed drawings for the various equipments covered in their scope for Employer’s approval. The equipment shall conform to type tests as per specification and applicable standards and reports of the same shall be furnished for approval.
1.04.00 Contractor shall furnish design calculations and construction drawings for all civil works showing details of pockets to be left in foundations and embedments to be provided in cable trenches.
1.05.00 Contractor shall furnish the schematics, general arrangement drawings, cable schedules, interconnection schedules, panel wiring diagrams etc. for various control and relay panels for Employer’s approval. Contractor shall also furnish the recommended relay settings to be adopted.
1.06.00 The Contractor shall note that the list of standards specified elsewhere in this specification is not complete. Whenever necessary the list of standards shall be considered in conjunction with specification, IS & IEC. In case governing standards for the equipment is different from IS or IEC, the salient points shall be clearly brought out alongwith English language version of the same.
1.07.00 Exposed live parts shall be placed high enough above ground to meet the requirements of Indian Electricity Rules and other statutory codes. All responsibilities regarding co-ordination with Electrical Inspection Agencies and obtaining clearance certificate from them rests with the Contractor.
1.08.00 All equipment shall be supplied with suitable terminal connectors. The terminal connector shall be well coordinated with the type/size of conductor and equipment to be connected. The conductor terminations for equipment shall be either rigid or expansion type suitable for tube or horizontal or vertical take off suitable for quad moose The spacing for quad moose ACSR conductor shall be 450 mm as required.
The exact requirement to terminal clamps would be finalised by the Contractor in consultation with Employer based on layout requirement. The terminal pads shall preferably be capable of taking the required conductor span under normal, short circuit and meteorological conditions, without affecting the performance of the equipment.
1.09.00 All equipment shall be supplied with necessary interpole cabling and its cost shall be included in the cost of equipment.
1.10.00 The minimum temperature is expected to reach upto -10 degree Celcius under extreme condition. The equipments shall be designed to withstand such conditions satisfactorily.
1.11.00 All equipment (outdoor) shall be suitable for hot line washing.
1.12.00 The Contractor shall cooperate in all respects and exchange the necessary technical data/ drawings with other agencies and Employer’s other Contractors under intimation to Employer to ensure proper coordination and completion of work in time.
1.13.00 Insulation Co-ordination and Selection of Surge Arrestor
1.13.01 The contractor shall be fully responsible for complete insulation co-ordination of switchyard including GIS. Contractor shall carry out detailed studies and design calculations to evolve the required parameters locations, energy capability etc. of surge arrestors such that adequate protective margin is available between peak impulse, surge and power frequency discharge voltages and BIL of the protected requirement. The locations of surge arrestors shown in single line diagram is indicative only. If the contractors feels that surge arrestors at some more locations are required to be provided, the cost for the same should also be included in the offer.
1.13.02 The contractor shall perform all necessary studies for surge arrestors. The report shall detail the limits of all equipment parameters which could affect the insulation co-ordination. The report shall also detail the characteristics of the surge arrestor and shall demonstrate arrestor’s protective and withstand levels, discharge and coordinating currents and arrestor ratings and comply with the requirement of this specification.
1.13.03 The contractor shall also consider in the studies, the open circuit breaker condition, fast transients generated by slow operation of disconnecting switches and high speed earthswitches etc. The study report and design calculations shall be submitted for Employer’s approval.
2.00.00 LT SWITCHGEAR AC Feeders:
The LT AC switchgear shall be designed to cater for all the loads required for bay marshalling kiosks, auxiliary power requirement. For reliability, each equipment and bay marshalling kiosk shall be connected with two independent sources of power supplies. The LT switchgear shall be suitable for power supplies to all Marshalling kiosks, maximum four (4) bay marshalling kiosks can be looped by forming a ring main. The LT switchgear panels shall be equipped with 20% spare feeders.
Two feeders of AC supply at 415V shall be available at Station Service Boards for connection to the (two) nos of 415V, 3 phase AC distribution boards with required no. of MCCB modules including 20% spare modules for switchyard requirement.
Additional 2 (two) feeders shall also be available from 415V Switchboard installed in pothead switchyard for catering power supply to outdoor switchyard.
DC Feeders:
The Contractor shall provide suitable DC distribution boards with busbars and all other equipments. For reliability, dual supplies for all loads shall be considered. 20%
spare feeders shall be provided.
4 (four) feeders of DC supply shall be available in unitized unit DC distribution boards of the power house for further connection to DC distribution boards for distribution.
3.00.00 CLEARANCES
The minimum clearances for 400 KV Outdoor Switchyard shall be as given below:
400KV
Phase to earth clearance 3500 mm Phase to phase clearance 4000 mm Section clearance 6500 mm
Ground clearance 8000 mm
The above clearances are valid upto altitude 1000M only. Bidder shall provide adequate clearances considering the altitude of the site. The Contractor shall supply the structures suitable to meet the clearances.
4.00.00 SERVICES TO BE PERFORMED BY THE EQUIPMENT BEING SUPPLIED
The 400 KV system is being designed to limit the power frequency over voltage of 1.5 p.u. and the switching surge over voltage to 2.5 p.u. In 400 KV system the initial value of temporary over voltage could be 2.0 p.u. for 1-2 cycles. All the equipment/materials covered in this specification shall perform all its functions satisfactorily without undue strain, restrike etc. under such over voltage conditions.
5.00.00 SYSTEM PARAMETERS
The system parameters shall be as under:
GIS AIS
a) Highest system voltage 420 KV rms 420 KV rms
b) System Frequency 50Hz 50Hz
c) Lightning Impulse Voltage
Phase to earth & between phases 1425 KV 1425 KV Across isolating distance 1425(+240) KV
d) Switching Impulse Voltage
Phase to earth 1050KV 1050 KV
Across isolating distance 900(+345) KV
Between phases 1575KV
e) Power frequency withstand for 1 min (rms)
Phase to earth & between phases 650KV 520 KV
Across isolating distances 815KV 610 KV f) PD level of GIS conductor Less than 5
Pico coulomb
Less than 10 Pico coulomb g) Corona Extinction voltage 320 KV (rms) h) Short Circuit current 40 kA for 1
sec.
40 kA for 1 sec.
The values of insulation level given above are applicable to altitude of 1000 M.
Bidder shall appropriately correct the values as per the site altitude.