WORKING ON TRANSFORMERS AND CIRCUIT BREAKERS SAFETY PRECAUTION TIPS AND TUTORIALS

SAFETY PRECAUTIONS ON WORKING ON TRANSFORMERS AND CIRCUIT BREAKERS
What Are The Safety Precautions on Working on Power Transformers and Circuit Breakers

Take the following safety precautions when working on transformers and circuit breakers:

• Prevent moisture from entering when removing covers from oil-filled transformers.

• Do not allow tools, bolts, nuts, or similar objects to drop into the transformers. Tie tools or parts with suitable twine.

• Have workers empty their pockets of lose articles such as knives, keys, and watches.

• Remove all oil from transformer covers, the floor, and the scaffold to eliminate slipping hazards.

• Exhaust gaseous vapor with an air blower before allowing work in large transformer cases because they usually contain some gaseous fumes and are not well ventilated.

• Stay away from the base of the pole or structure while transformers are being raised or lowered.

• Ensure that anyone working on a pole or structure takes a position above or well clear of transformers while the transformers are being raised or supported with blocks.

• Ground the secondary side of a transformer before energizing it except when the transformer is part of an ungrounded delta bank.

• Make an individual secondary-voltage test on all transformers before connecting them to secondary mains. On banks of three transformers connected Y-delta, bring in the primary neutral and leave it connected until the secondary connections have been completed to get a true indication on the lamp tests.

• Disconnect secondary-phase leads before opening primary cutouts when taking a paralleled transformer out of service. Do not disconnect secondary neutral or ground connections until you have opened the primary cutouts.

• Do not stand on top of energized transformers unless absolutely necessary and then only with the permission of the foreman and after all possible precautions have been taken. These precautions include placing a rubber blanket protected with a rubbish bag over the transformer cover. Do not wear climbers.

• Treat the grounded case of a connected transformer the same as any grounded conductor. Treat the ungrounded case of a connected transformer the same as any energized conductor because the case may become energized if transformer windings break down.

• Ensure that the breaker cannot be opened or closed automatically before working on an oil circuit breaker and that it is in the open position or the operating mechanism is blocked.

• Ensure that metal-clad switching equipment is deenergized before working on it.

• Ensure that regulators are off the automatic position and set in the neutral position before doing any switching on a regulated feeder.

• Do not break the charging current of a regulator or large substation transformer by opening disconnect switches because a dangerous arc may result. Use oil or air brake switches unless special instructions to do otherwise have been issued by the proper authority.

• Do not operate outdoor disconnecting switches without using the disconnect pole provided for this
purpose.

• Ensure that all contacts are actually open and that safe clearance is obtained on all three phases each time an air brake switch is opened. Do not depend on the position of the operating handle as evidence that the switch is open.

• Do not operate switches or disconnect switches without proper authority and then only if thoroughly
familiar with the equipment.

• Remove potential transformer fuses with wooden tongs. Wear rubber gloves and leather over gloves.

• Do not open or remove disconnect switches when carrying load. First open the oil circuit breaker in series with the switches. Open disconnect switches slowly and reclose immediately if an arc is drawn.