We often depends Diesel Electrical Genset as emergency power system due to mains failure. As a professional, the installation of diesel electrical power generator should be as per the clients requirement and to be inline with the authoritative norms and standards. Safety, security, convenience, future expansions etc are to be considered and co-ordinated before start detailing of the genset's installation. The generator should be as close to the main change-over board as possible. In cases like Textile Mills, where there is fear of smoke affecting the quality of the yarn etc., generators may be located away from the Plant / Department.
- The generator should be erected in a well ventilated room preferably with a ridge opening. It is not desirably to locate this in the basement.
- The generator should be so erected that the radiator of the engine is facing the opening for effective heat radiation.
- A minimum clear space of 750mm should be provided all around the generator.
- The applicable de-rating factors, as recommended by the manufacturer of the generator, for the de-ration of the capacity of the generator should be given due consideration for the design of the installation.
- Generally armoured cables should be used for connecting the generator. If un-armoured cables are used, these should be enclosed in earthed metallic casings.
- The control panel of the generator should be located away from the generator, but in the same room. The clearance between the generator and the control panel should be more than 1 metre, for small sets upto and including 5OO KVA. For larger sets, more separation for proper cooling is the deciding factor.
- When two generators are erected side by side, a minimum clearance of 1500 mm should be provided between the generators.
- The control panel of the generator should be erected with clearances as applicable to switch boards.
- The generator shall be complete with control panel, daily service tank, underground bulk storage tank and transfer pump set with duty/standby pumps.
- The control panel should comprise of means for adequate control and protection for the generator supply with required meters and indication lamps and should be vermin proof.
- The control and protection may be is follows:
- Upto and inclusive of 100 KVA: Switch fuse, Fuse Switch or Circuit Breaker
- Above 100 KVA: Circuit Breaker.
- Where fuses are provided as back up protection before the circuit breaker / contactor and also in cases where fuses alone are provided in Control Panels of the Generator, a linked switch or isolator should be provided before the said fuses for isolation and to facilitate safe renewal of fuses.
- Tapping of supply to the auxiliaries of Generator should not be taken from the control panel of generator, if there is no provision made by the manufacturer of the generator for such tapping.
- A link should be introduced in the neutral circuit of the generator and the neutral earthing should be done at the outgoing side of the link. The neutral earthing and the neutral link should be at the control panel. If no provision is available for this in the control panel, it should be done at the terminal box of the generator.
- The generator should never be run in parallel with the Electricity Supply Authorities' main grid.
- Double throw knife type change-over switch is not to be normally employed for change-over of supply.
- On the change-over board, a pair of 4 pole fuse switches mechanically interlocked should be used for each TPN feeder. However, TP FS is permissible if the outgoing cable is a three core cable.
- If automatic change-over arrangement is provided, the interlocked contactors should be of 4 pole type for TPN supply. If the incoming supply source is far away, suitable isolator / Fuse switch should be provided before the contactor for each incoming supply.
- Where generators are to be operated in parallel, there should be suitable paralleling arrangement with at-least Fuse Switch and contactor or Circuit Breaker for each generator for quick operation. If Circuit Breakers are used, these should be draw-out type and if non draw-out type circuit breaker is used, an isolating device should also be provided before the non-drawout circuit breaker to permit safe working on individual generator, while the other set in operation. There should also be provision for isolation of neutral of each generator and this neutral isolator should be closed first while closing and opened last while switching off.
- The following remote indications shall be displayed in the control room through Building Management or Plant Control System:
- Generator status: Run/Stop, Voltage, Load current, Frequency, oil pressure, engine temperature etc.
- Automatic Transfer Switch Status: Mains/Standby.
- Mains power status: ON/OFF for each switchboard section.
- Generator trouble:
- Fail to start.
- Voltage trouble.
- Frequency trouble.
- High Engine Temperature.
- Low oil pressure.
- Over-speed.
- Alternator low and over voltage.
- High winding temperature.
- Daily Fuel tank:
- High Level
- Low Level
- Bulk Storage tank:
- High Level
- Low Level
- Fuel Oil transfer pump status:
- RUN/STOP
- Trouble.
- In case of HV Generators, if isolator or Circuit Breakers is provided for neutral, necessary mechanical-interlock should be provided between the neutral isolator / or Circuit Breaker so that neutral isolator / or Circuit Breaker in the neutral circuit is closed before closing the main circuit breaker of generator and vice versa.
- No oil drums and other containers should be stored in the generator room and the room should not be used for any extraneous purposes, nor any equipment pertaining to other services installed therein.
- All generators with rating of 100 KVA and above shall be protected against earth fault leakage. All generators of 1000 KVA and above Shall be protected against faults within the generator winding using restricted earth fault protection or differential protection or by both.
- The turbo alternators in co-generation plants require detailed protection and require special consideration since such alternators are operated in parallel with the supplier's grid. Both supply company sanction and Government permission are required for the tie up.
