Operating the Circuit Breaker

Circuit Breaker Status

The indicators on the front of the circuit breaker show the following information:

• Blue fault-trip reset button:

  • In: the circuit breaker is closed or open voluntarily (not tripped)

  • Out: the circuit breaker has tripped

• Position indicator of main contacts: ON or OFF.

• Closing spring and ready-to-close indicator. The state can be one of the following:

  • Discharged (no energy to close the circuit breaker)

  • Charged not ready-to-close

  • Charged ready-to-close

A Blue fault-trip reset button

B Position indicator of main contacts

C Closing spring and ready-to-close indicator

The combination of both indicators gives the circuit breaker status:

Position indicator of main contacts	Closing spring and ready-to-close indicator	Circuit breaker status description
		Circuit breaker is off (main contacts are open) and closing spring is discharged.
		Circuit breaker is off (main contacts are open) and closing spring is charged. The circuit breaker is not ready-to-close because at least one of the following conditions is true: The circuit breaker has tripped and must be reset. The MX opening voltage release is energized. The MN undervoltage release is not energized. The circuit breaker is mechanically locked in the open position by using padlock or keylock or by using an interlocking system.
		Circuit breaker is off (main contacts are open) and closing spring is charged. The circuit breaker is ready-to-close.
		Circuit breaker is on (main contacts are closed) and closing spring is discharged.
		Circuit breaker is on (main contacts are closed) and closing spring is charged. The circuit breaker is not ready-to-close because it is already closed.

Circuit Breaker Indication Contacts

The position of the circuit breaker main contacts is indicated by OF indication contacts.

Name	Contact number	Position of indicators and contacts
Circuit breaker status	–	ON	OFF	Tripped (by MicroLogic Active control unit)
Position indicator of main contacts	–
Main contact position	–	Closed	Open	Open
Blue fault-trip reset button position	–	IN	IN	OUT
OF indication contact position	1–2	Open	Closed	Closed
	1–4	Closed	Open	Open
SDE indication contact position	1–2	Closed	Closed	Open
	1–4	Open	Open	Closed

Anti-Pumping Function

MasterPacT MTZ circuit breakers provide a mechanical anti-pumping function. In the event of simultaneous maintained opening and closing orders, the standard mechanism blocks the main contacts in the open position. After a trip due to an electrical fault or intentional opening using the manual or electrical controls, the closing order must first be discontinued, then reactivated to close the circuit breaker. This prevents a cycle of closing and opening.

When remote operation features are used, allow at least four seconds for the MCH gear motor to charge the circuit breaker closing spring completely before the XF closing voltage release is actuated.

To prevent the circuit breaker from closing prematurely, the PF ready-to-close contact can be series connected with the XF closing voltage release.

Charging the Closing Spring

Manual Operation Cycle with the Spring Charging Handle

The following image shows an Open/Close/Open (OCO) cycle for manually charged circuit breakers without MCH gear motor:

Electrical Operation Cycle with an MCH Gear Motor

The following image shows an Open/Close/Open (OCO) cycle for electrically charged circuit breakers using an MCH gear motor: