The Siemens 3VA9978-0BL31 is a SENTRON shunt trip — an auxiliary release that sits in the left accessory slot of 3VA4, 3VA5, and 3VA6 molded-case circuit breakers. That's your emergency-stop or undervoltage-release circuit sorted without a separate contactor.
The coil draws 30 VA apparent (30 W active at DC), which is the load the control transformer or power supply has to handle. At 48 V that's about 0.63 A; at 60 V about 0.5 A.
This is a snap-in accessory for the left side of 3VA4/5/6 breakers. The breaker's own DIN-rail mount carries it; no extra panel space needed. The 10 mm stripped length on the wiring terminals matches standard ferrule or solid-wire prep for the control circuit.