I) Danger signs should be displayed to warn persons the presence of high voltage equipment.
II) Gates in switchyard fences and doors to bus compartments and other enclosures containing live equipment should be kept locked at all times except when men are working inside.
III) Unauthorized persons should not be allowed inside a hazardous operation area like a bus compartment, switchyard etc. unless such a person is accompanied by a responsible person who shall always be present while such person remains in the area. Any person deputed to clean the floors or parts of the plant in such areas must be given clear instructions and a responsible person must be present while the man is carrying out the work to ensure that the man does not endanger his own safety.
IV) Before doing any work on rotating equipment, it should be shut down and properly disconnected from power source.
V) Care should be taken to prevent clothing, wiping cloths, waste dusters, oil cans or tools from getting caught in the moving parts of machinery.
VI) When using compressed air on live electrical machinery, an insulating hose and nozzle should be used. Dust proof goggles should always be used when cleaning with compressed air. Compressed air should never be used for cleaning or dusting clothes or any part of the body.
VII) If men are working on H.T. (voltage above 650V) equipment, the area safeguarded for work shall be cordoned off by tieing a white rope or cotton tape all round and danger boards shall be fixed within the safe guarded area at various location with the inscription facing the safe working area to warn the men not to cross over the area with live equipment during the progress of work.
VIII) It should be ensured that maintenance and repair works are done promptly before the equipment deteriorates further and become a source of danger. It shall be also ensured that defective equipment is not retained in any other means than the stick or operating gear provided for this purpose.
The person using the switch stick should ensure himself of a secure footing and proper clearance from other equipment and should wear rubber gloves of adequate insulating value for the voltage of the disconnecting switch or fuse and in good condition.
2) Transformers:-
i) When work is to be carried out on a transformer, both the low and high tension (Primary & secondary sides) breakers and isolator shall be opened.
Similarly when isolating transformers to which potential transformers are connected, such potential transformers shall be isolated and secondary P.T.
fuses removed to prevent any possibility of transformer being made alive through synchronizing or voltmeter plug.
ii) Before commencing any work on a transformer, the transformer winding should be discharged to ground. In case the transformer is isolated from the supply by single point of disconnection e.g. fuse, the transformer shall be
safeguarded by shorting the phase terminals together and connecting them to ground, before commencing any work. The neutral ground of a transformer should never be treated as the grounding of phase terminals, as required above.
3) Instrument Transformers:-
i) The instrument transformers should be grounded.
ii) One lead of the secondary circuit of the current transformers should be connected to ground at all times when the C.T. is in service.
iii) Potential transformer secondary should never be shorted to ground except star point.
iv) The low voltage winding of potential transformers should always have one side permanently and effectively grounded.
4) Capacitors:-
i) Every capacitor shall be treated as ‘hot’ until proved otherwise.
Capacitors store energy and are not necessarily dead when disconnected from the lines. Once charged, a capacitor may retain this charge for several hours after it has been disconnected.
ii) Before commencing work on the capacitors, first open all cut-outs or disconnecting devices to the capacitors, then wait for at least five minutes for the internal resistor to reduce the voltage. Next using a hot stick, short circuit and ground all terminals of the capacitor. The short circuit grounding jumpers should be left attached while work is being done on the capacitor.
iii) To place the capacitor banks in service, first remove the jumpers with hot sticks, and then close the cut-outs.
D/C distribution:-
1) D/C Distribution Board (DCDB)/Battery Charger must be cleaned regularly.
Connections must be Tight / Rigid.
2) Only H.R.C. fuses of adequate and correct rating shall be used. Maintain the stock in the substation site store.
3) On DCDB, every DC feeder DC Cable provided for bay shall be named separately.
4) Separate Room shall be provided for DC distribution system in the substation.
5) AC power cables & DC control cables shall be run separately in cable Trench as soon as possible.
6) Do not pull out the control cables with force & Jerk.
7) The defective cable shall be removed from Trench. Both ends of the cable must be made free first, pull the cable gently/smoothly, without disturbing other live cables.
EHV substation shall maintain following T&P (minimum) for safe working.
1) Ten sets of discharge rods.
2) Good quality Torch (4nos) with fresh cells 3) First Aid Box
4) Tool Box (2nos) containing Insulation, Tape, all size ring & flat spanners, Allen key set, pliers (big, small size) Insulation cutter etc.
5) H.R.C. fuses of various capacities.
6) Ladder (4nos.) 7) Rope
8) A/C Distribution Board with adequate wiring set.
9) Tong Tester.
1) Police station of concerned Area.
2) Ambulance service
3) Govt. Hospitals (near to S/S) 4) Fire brigade station
5) Electrical Inspector.
6) Mobile number of following persons.
1) Substation in charge
2) Fire drill head of the substation 3) Ambulance service
4) Fire brigade.
5) Security head/person.