Responding to a Trip

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E, CSA Z462, NOM-029-STPS, or local equivalent. This equipment must only be installed and serviced by qualified electrical personnel. Turn off all power supplying this equipment before working on or inside equipment. Always use a properly rated voltage sensing device to confirm that power is off. Replace all devices, doors, and covers before turning on power to this equipment. Beware of potential hazards, and carefully inspect the work area for tools and objects that may have been left inside the equipment. Failure to follow these instructions will result in death or serious injury.

Before inspecting electrical equipment downstream of the circuit breaker, always isolate the feed.

A trip can be caused by the following events:

• Fault detected on the installation

• Fault detected caused by a malfunction

• Intentional tripping

Check the circuit breaker and the electrical installation to find the root cause of the trip.

WARNING
HAZARD OF CLOSING ON ELECTRICAL FAULT Do not close the circuit breaker again without first inspecting and, if necessary, repairing the downstream electrical equipment. Failure to follow these instructions can result in death, serious injury, or equipment damage.

The fact that the protection has tripped does not remedy the cause of the fault detected on the downstream equipment.

Perform the following tasks after a short-circuit:

• Carefully clean off any traces of black smoke. The smoke particles can conduct electricity.

• Check the power connections and control wires.

• Operate the circuit breaker at least five times at zero load.

Depending on the type of fault detected, perform the following inspections on all or part of the equipment where the fault occurred:

• For faults tripped by thermal protection:

  • Check the system for damage, and then repair if necessary.

  • Perform checks E and G.

• For faults tripped by magnetic protection or caused by an unknown reason:

  • Check the system for damage, and then repair if necessary.

  • Perform checks A, E, and G.

• For faults tripped by earth-leakage protection:

  • Check the system for damage, and then repair if necessary.

  • Perform checks E, G, and I.

Before resetting the circuit breaker, make sure that the fault is identified and repaired, and that the installation has been checked.

If the system must be restarted quickly (for example, in a safety installation), isolate and lock out the affected part of the installation before carrying out maintenance.

The procedure for resetting a circuit breaker depends on the type of handle on the circuit breaker.