The 3VA Circuit Breaker family offers a wide variety of internal accessories including auxiliary switches, alarm switches, shunt trips in various voltages, undervoltage trip units in various voltages, a universal release and a time delay for the undervoltage trip units.

Auxiliary switches

All auxiliary and alarm switches for the 3VA UL molded case circuit breakers belong to an integrated range of accessories. The auxiliary switches can be simply snapped into place and connected up in the accessories compartment provided on the front face of the unit to the left and right of the handle. The purpose of the auxiliary switches (AUX) is to signal the position of the main contacts of the molded case circuit breaker. The contacts of the auxiliary switches open and close simultaneously with the main ontacts of the molded case circuit breaker. Leading changeover switches (LCS) signal the opening of the main contacts with a lead time of 20 ms in advance of the circuit breaker opening and could be used to deactivate a frequency converter, for example. Trip alarm switches (TAS) signal every circuit breaker tripping operation, regardless of the cause of the trip. The trip alarm switches are actuated whenever the molded case circuit breaker switches to the TRIP position. Electrical alarm switches (EAS) are actuated as soon as the main contacts of the molded case circuit breaker open in the event that the breaker is tripped by the ETU. Special electronically-compatible (el) variants are available for applications that require the auxiliary switch signals to be linked to low voltage systems.

Auxiliary releases

Auxiliary releases allow remote electrical tripping of the circuit breaker. They can be used to monitor control or main circuits in order to implement a protective system against accidental restart following a power failure, for example. Undervoltage releases trip the 3VA UL molded case circuit breaker in the event that the rated voltage of a monitored circuit drops below a minimum permissible limit or fails altogether. Shunt trips can be used to trip the 3VA UL molded case circuit breaker remotely. The STF variant can be mounted in either the left-hand or the right-hand accessories compartment (for 3VA6 only). The STL type is specifically designed for mounting in the left-hand compartment and is a very low power consumption device. A universal release is a single, 21 mm wide component in which a shunt trip and an undervoltage release are combined. These are subject to the same tripping conditions as the individual devices.