The Siemens SENTRON 3VA9978-0AA11 is an auxiliary switch with changeover contacts, type HP, designed as a snap-on accessory for 3VA4, 3VA5, and 3VA6 molded-case circuit breakers. It provides remote status indication — open/closed/tripped — via its changeover contact set, wired back to a PLC or indicator lamp in the panel. Rated thermal current (Ith) is 10 A, which sets the continuous current-carrying capacity of the contacts under open-air conditions. The actual switching capacity depends on the load type and voltage: per the datasheet, at AC-15 (solenoid/contactor control) it handles 6 A up to 48 V and derates to 0.6 A at 600 V; at DC-13 (solenoid/electromagnet with parallel diode) it carries 3 A at 12/24 V and drops to 0.1 A at 250 V. The 14 mm housing width matches the standard 14 mm per-pole module footprint of the host breaker, so it occupies one additional module space on the DIN rail. Stripped length for the screw-clamp terminals is 15 mm (0.6 in), accepting conductors up to the breaker's terminal capacity.
This auxiliary switch snaps onto the left or right side of a 3VA4, 3VA5, or 3VA6 breaker frame. It does not require additional DIN-rail space beyond the breaker's own mounting; the switch clips into the breaker's accessory slot and becomes mechanically ganged with the operating mechanism. The changeover contacts (one normally-open, one normally-closed, common) are wired to the control circuit via the screw terminals. The surge voltage resistance of 4 kV confirms coordination with standard 400 VAC distribution systems.