The Siemens SENTRON 3VA9137-0HA20 is a motorized operating mechanism (MO) — a panel-mount accessory that remotely opens and closes the 3VA5 125 molded-case circuit breaker. It's the part that lets a PLC or remote pushbutton toggle the breaker without someone standing at the panel door.
Rated control supply voltage spans 110-230 V AC at 60 Hz and 110-250 V DC, so it covers standard North American 120 V and 208-240 V control circuits as well as common DC bus voltages. The operating apparent power draw is 250 VA — that's the inrush to pull the solenoid and charge the mechanism spring. Make time and break time are both 0.8 s typical. That's a deliberate, slow operation — not a high-speed shunt trip. It's sized for remote switching duty where you want a controlled open/close sequence, not for instantaneous fault interruption. Dimensions are 76 mm wide, 70 mm high, 103 mm deep. That depth — 103 mm — is the critical one for enclosure clearance. Make sure the panel door or deadfront clears that projection when the mechanism is mounted on the breaker. Stripped length for the control wiring is 7 mm — standard for screw-clamp terminals on these Siemens accessories. No special ferrule needed.
This MO mounts directly onto the 3VA5 125 molded-case circuit breaker frame. No separate DIN footprint — it rides with the breaker. The 80 °C max is the internal mechanism limit, not the breaker's — the breaker itself may have a lower ambient derating curve.