What to Do When the Circuit Breaker Trips

Overview

Local and remote indication provides information on the probable cause of a trip. In particular, the indications specific to the MicroLogic trip unit provide a high level of certainty about the cause of the trip (see MicroLogic trip unit user guides).

There are several types of trip cause:

• Electrical faults on the installation

• Device malfunction

• Intentional tripping

Note the Trip

Trips are signalled locally and remotely by the indicators and auxiliary contacts installed on devices (depending on each configuration). See ComPacT NS Electrical Auxiliaries and the user guide of the trip unit for information on the trip indications available with your device.

Identify the Cause of Tripping

Identify the cause of tripping. A circuit breaker must never be reclosed (locally or remotely) before the cause of the trip has been identified and cleared.

Depending on the type of trip and the criticality of the loads, a number of precautionary measures must be taken, in particular the insulation and dielectric tests on a part of or the entire installation. These checks and test must be directed and carried out by qualified personnel.

Inspect the Circuit Breaker Following a Short-Circuit

• Check the tightness of connections (see the device installation manual).

• Check the disconnecting contact clusters.

Reset the Device

The device can be reset locally. See detailed topic for information about how the device can be reset:

• For ComPacT NS630b-1600 with toggle handle

• For ComPacT NS630b-1600 with direct rotary handle

• For ComPacT NS630b-1600 with extended rotary handle

• For ComPacT NS1600b-3200

Maintenance of the Equipment Following Trip on Electrical Fault

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

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. This equipment must be installed and serviced by qualified electrical personnel. Disconnect all power sources before performing maintenance inspections. Assume that all circuits are live until they are completely de-energized, tested, grounded and tagged. Consider all sources of power, including the possibility of backfeeding and control power. Always use a properly rated voltage sensing device to confirm power is off. Put back all devices, doors and covers before turning on power to this equipment. Failure to follow these instructions will result in death or serious injury.

CAUTION
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 injury or equipment damage.

Depending on the type of electrical fault, maintenance inspections must be carried out on all or part of the equipment where the electrical fault occurred (see Commissioning):

• Minor faults:

  • Tripped by long time protection

  • Tripped by earth-leakage protection

    Following repairs, checks D, E, and F must be carried out.

• Serious or destructive faults:

  • Tripped due to unknown electrical fault

  • Tripped by short time protection

  • Tripped by ground fault protection

Following repairs, checks A, B, D, E, and F must be carried out. The device that tripped must be specifically checked (see Maintaining the ComPacT NS During Operation) before being returned to service.