Abstract: Protection is provided for servicing a distribution bus by grounding the line side of a circuit breaker through which the distribution bus is fed and then closing the circuit breaker. The trip unit of the circuit breaker includes logic, in addition to the normal protection logic, which opens the circuit breaker main contacts without delay if current is detected upon closing of the grounded circuit breaker. However, if the grounded circuit breaker has been closed for a selected period of time and then current is detected, the distribution bus is kept at zero potential by not operating the breaker. A breaker auxiliary switch with a mechanical delay provides the indication of the selected time interval after closing the circuit breaker.

Abstract: Protection is provided for servicing a distribution bus by grounding the line side of a circuit breaker through which the distribution bus is fed and then closing the circuit breaker. The trip unit of the circuit breaker includes logic, in addition to the normal protection logic, which opens the circuit breaker main contacts without delay if current is detected upon closing of the grounded circuit breaker. However, if the grounded circuit breaker has been closed for a selected period of time and then current is detected, the distribution bus is kept at zero potential by not operating the breaker. A breaker auxiliary switch with a mechanical delay provides the indication of the selected time interval after closing the circuit breaker.

Abstract: A circuit breaker includes a set of main separable contacts, an operating mechanism for operating the main separable contacts, a set of secondary separable contacts in series with the main separable contacts, and a solenoid mechanism for operating the secondary separable contacts. A first auxiliary switch is responsive to the operating mechanism, and a second auxiliary switch, electrically connected to the first auxiliary switch, is responsive to the solenoid mechanism. An input terminal for a control voltage is electrically connected to the first and second auxiliary switches. A first diode is electrically connected with a forward polarity between the first auxiliary switch and an output terminal. A second diode is electrically connected with a reverse polarity between the second auxiliary switch and the output terminal.

Abstract: A circuit breaker includes a set of main separable contacts, an operating mechanism for operating the main separable contacts, a set of secondary separable contacts in series with the main separable contacts, and a solenoid mechanism for operating the secondary separable contacts. A first auxiliary switch is responsive to the operating mechanism, and a second auxiliary switch, electrically connected to the first auxiliary switch, is responsive to the solenoid mechanism. An input terminal for a control voltage is electrically connected to the first and second auxiliary switches. A first diode is electrically connected with a forward polarity between the first auxiliary switch and an output terminal. A second diode is electrically connected with a reverse polarity between the second auxiliary switch and the output terminal.