Responding to a Trip

Taking Precautions Before 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 or CSA Z462 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. Put back all devices, doors, and covers before turning on power to this equipment. Repair the installation immediately if an insulation fault occurs during operation. Failure to follow these instructions will result in death or serious injury.

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462 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.
Put back all devices, doors, and covers before turning on power to this equipment.
Repair the installation immediately if an insulation fault occurs during operation.

Failure to follow these instructions will result in death or serious injury.

Identifying the Cause of the Trip

Local and remote indication provides information on the probable cause of a trip. In particular, the MicroLogic 5, 6 or 7 trip units provides specific information about the cause of the fault detected. For more information, refer to DOCA0141EN, ComPact NSXMicroLogic 5/6/7 Electronic Trip Units - User Guide.

The causes are of several types:

Fault detected on the installation
Fault detected due to a malfunction
Intentional tripping

Trip Following a Fault on the Installation

The control mechanism is positioned on , Trip.

Indication			Probable cause
TM-D	MicroLogic 2 and 4	MicroLogic 5, 6, and 7	Probable cause
SD	SD	SD and information on the display	Tripped manually by: Push-to-trip test Manually opening the motor mechanism Disconnecting the circuit breaker from plug-in base with circuit breaker in ON position MN or MX releases
SD and SDE	SD, SDE, and SDT	SD, SDE, and SDT and information on the display	TM-D: Tripped on electrical fault, cause unknown MicroLogic 2 and 4: Tripped by long-time protection MicroLogic 5 and 6: Tripped by long-time protection (or example, on phase 1 at 930 A, as shown)
	SD and SDE	SD and SDE and information on the display	TM-D: Tripped on electrical fault, cause unknown MicroLogic 2 and 4: Tripped by short-time or instantaneous protection (short-circuit) MicroLogic 5, 6 and 7: Tripped by short-time or instantaneous protection (short-circuit) on short-circuit (for example, on phase 2 at 18 kA, as shown)
	SD, SDE, and SDx	MicroLogic 7 SD, SDE, and SDx and information on the display	MicroLogic 4: Tripped by earth-leakage protection MicroLogic 7: Tripped by earth-leakage protection
SD, SDE, and SDV Button R on VigiPacT Add-on in the out position	SD, SDE, and SDV Button R on VigiPacT Add-on in the out position	MicroLogic 5 SD, SDE, and SDV Button R on VigiPacT Add-on in the out position and information on the display	TM-D: Tripped by earth-leakage protection MicroLogic 2: Tripped by earth-leakage protection MicroLogic 5 and 6: Tripped by earth leakage protection (no other faults reported)
–	–	MicroLogic 6 SD, SDE, and SDG and information on the display	MicroLogic 6: Tripped by ground-fault protection

Maintenance of the Equipment Following Trip on Fault

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

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.

Isolate the feed before inspecting the electrical equipment downstream of the protection.

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, perform maintenance inspections on all or part of the equipment where the fault occurred:

Minor faults:
- Tripped by long-time protection
- Tripped by earth-leakage protection
Following repairs, checks D, E, F, and G 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, F, and G must be carried out. Check the circuit breaker that tripped before being returned to service.

NOTE: Checks, tests, and inspections must be carried out by qualified electrical personnel.

If restarting is a high priority (for example, a safety installation), the defective part of the installation must be isolated and locked in order to carry out this maintenance.