Resetting the Circuit Breaker after a Trip Due to an Electrical Fault

Masterpact MTZ1 Circuit Breaker Reset Sequence

The table shows the sequence of actions to follow after a trip due to an electrical fault. Further explanation of each action is given in the following paragraphs.

Step	Description
1	Identify the trip cause by using the Micrologic X control unit HMI.
2	Acknowledge the trip message on the Micrologic X control unit.
3	Clear the electrical fault on the network .
4	Inspect the circuit breaker and switchboard after a short circuit.
5	Reset the circuit breaker (see Resetting Masterpact MTZ Devices).
6	When the circuit breaker is ready-to-close, re-close it (see Closing the Masterpact MTZ1 Mechanism).

Identifying the Masterpact MTZ Trip Cause

Trip Cause LEDs	Control Unit	Description
	Micrologic 3.0 X, 5.0 X, 6.0 X	Trip due to the long-time protection.
	Micrologic 5.0 X, 6.0 X	Trip due to the short-time protection or instantaneous protection.
	Micrologic 3.0 X, 5.0 X	Not used.
	Micrologic 6.0 X	Trip due to the ground-fault protection.
	Micrologic 3.0 X, 5.0 X, 6.0 X	Trip due to other protection (optional protections).

NOTE: Diagnostic assistance can be obtained by using a smartphone running the Masterpact MTZ Mobile App.

Acknowledging a Trip Message on Micrologic X Control Units

Step	Action
1	Press OK to view details of the trip cause on the display screen.
2	Consult the two tripping context screens: Screen 1: Name and settings of the tripping protection. Date and time of the trip. Screen 2: Current values recorded before the trip.
3	Press OK to acknowledge the trip and return to the Home menu. NOTE: If the trip is not acknowledged within the event timeout, the pop-up is displayed again.
4	Press the Test/Reset button for 3 seconds to reset the control unit and switch off the trip cause and service LEDs.

Clearing the Electrical Fault Before Reclosing the Masterpact MTZ Circuit Breaker

The fact that a circuit breaker has tripped does not remedy the cause of the electrical fault detected on the downstream electrical equipment.

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.

The feed must be isolated before inspecting the electrical equipment downstream of the protection.

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 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 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 that power is off. Replace all devices, doors, and covers before turning on power to this equipment. 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, CSA Z462, NOM 029-STPS or local equivalent.
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 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 that power is off.
Replace all devices, doors, and covers before turning on power to this equipment.

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

Inspecting the Masterpact MTZ Circuit Breaker and Switchboard after a Trip on a Short Circuit

After a trip on a short circuit due to short-time or instantaneous protection, the circuit breaker and switchboard must be inspected for smoke deposits or cracks in the device casing.

Refer to Masterpact MTZ Circuit Breakers - Maintenance Guide (DOCA0099EN) and contact a Schneider Electric field service representative.