Ancillary electrical works for Setting up of 50 Bedded Critical Care Hospital Block at Malda Medical College and Hospital, Malda. (Electrical Work)_External E.I. Work (Substation and Compound Light)

SITC 11 KV HT PANEL

Supply, Installation, testing & commissioning of 11 kV, 800A, short-circuit capacity of 26.3 kA for 3 sec 4-panel HT Gear with VCBs as per Specification [Make - SIEMENS / ABB / Crompton Greaves / L&T/Schneider] below :-

PANEL The HT panel is rated at 11 kV, 3-Phase 800A, Breaking Current/short-circuit capacity of 26.3kA for 3 sec, 50c/s and shall be of floor-mounting, sheet steel clad, free-standing metal enclosed air insulated switchgear cubicle with VCB inside. The Vacuum Circuit Breaker (Make- Schneider Electric / SIEMENS / ABB / Crompton Greaves / L&T) is horizantal isolation & horizantal drawout/Vertical isolation & horizontal drawout with 3 compartments and is made of 2mm CRCA sheet for load bearing members with vermin & moisture proof along with automatic shutter arrangement for complete isolation of bars, cable sockets & other live parts etc. when the removable portion is withdrawn. The breaker is arranged for hand operation through front of the panel push buttons & spring charging mechanism and also electrical motor which will be energizied by 230V AC. Closing and tripping coils are rated for 110V DC to be made available from local power supply 230V, 50 Hz, AC with remote operation compatibility. The shutter shall be gravity operated.

FRONT DOOR High-Voltage door during switching operations, the high-voltage door should remain closed and mechanical interlock should prevent opening of door when the switching device is in service and is switched ON. The position of the withdraw-able section, the CLOSED/OPEN switch position of the switching device, the operating cycle counter and the “spring charged” indication should be visible through pressure-resistant inspection windows in the high-voltage door. The panel front door can be closed with the breaker in isolated position. The degree of protection in the panel is IP-43 as per Indian Standard IS 3427.

BUSBAR The spacious bus bar compartment is provided on the top of the cubicle. The main bus bar can carry current upto 1000A and are made of electrolytic grade Aluminum & shall be vertically placed one after another. The bus bars should be air insulated but must be HT PVC sleeved & color coded for R-Y-B. No live parts should be accessible. All joints should be insulated covered and color coded for easy identification.

BREAKER The vacuum circuit breaker is mounted on a truck and is of horizontal isolation and horizontal drawout/Vertical isolation & horizontal drawout type having a robust motorized mechanism. The spring charge cycle duty of mechanism is O-C-O. The vacuum circuit breaker is single break design and have one vacuum interrupter per phase. The minimum operational life of the vacuum interrupter is 30,000 mechanical, 10,000 electrical at rated current & 100 at rated short circuit. The breaker is having auxiliary switch 6NO+6NC. [OEM Certificate to be provided]

EARTHING A continous copper earth bus runs across the entire length of the switchboard. All doors partitions, covers and non current carrying metallic parts are earthed to achieve earth potential for the entire enclosure. Terminals are provided at each end of the earth bus to connect the grid earthing. If integral earthing facility is not available separate earthing truck shall be provided for earthing.

INTERLOCK The circuit breaker can be operated only in service/test position and not in any intermediate position, beside fully isolated condition. The circuit breaker cannot be inserted into service position in closed condition and cannot be removed from service unless it is in open condition. The circuit breaker cannot be moved from test position to service position unless auxiliary plug is engaged and auxiliary plug cannot be disengaged if the breaker is in service position. If earth switch is provided it shall be mechanically interlocked with the breaker so that both the devices can not be 'ON' simultaneously.

CURRENT TRANSFORMER The current transformer should be wound type. Cast resin encapsulated current transformer 150/5,5A for I/C & 75-60/5,5A for O/G CT with multicore arrangement is acceptable. Metering core should be of class 1.0 & protection core shall be of class 5P10. The CT should have at least 25% over capacity than total connected load. The CT should be capable to withstand the rated full short circuit current for minimum 1 second.

POTENTIAL TRANSFORMER The potential transformer is drawout type with HRC fuses provided in both the sides of primary & secondary. The PT shall be cast resin moulded & insulated type encapsulated & 3- phase type with Dyn11 connection. It should be of class 1.0 with over-voltage factor 1.2 conntinuous for a solidly grounded system.