What it is and where it fits
The Siemens 3VM9908-0BL30 is a shunt trip (auxiliary release) for the SENTRON 3VM molded-case circuit breaker family, rated for breakers up to 630 A. It mounts on the left side of the breaker and triggers a remote trip when its coil is energized — standard practice for emergency-stop circuits, undervoltage protection schemes, or interlocking between breakers in a distribution panel. Coil accepts 24 V AC at 50/60 Hz or 12–30 V DC, drawing up to 30 VA apparent power on AC or 45 W active power on DC. That 45 W DC figure is the peak inrush; steady-state hold is lower, but the control transformer or DC supply must be sized for the inrush without voltage sag.
Panel fit and wiring
The shunt trip occupies a compact footprint — 65.1 mm tall, 25.7 mm wide, 31.2 mm deep — and clips directly onto the left side of the 3VM breaker without additional DIN-rail space. The stripped length of 10 mm (0.4 in) on the flying leads matches standard ferrule or direct-wire termination in the control cabinet. Overvoltage category III and pollution degree 3. Surge voltage resistance of 4 kV.