The built-in undervoltage release (UVR) drops the breaker if control voltage falls below the dropout threshold — common in emergency-stop or mains-monitoring circuits where a loss of control power must open the feeder.
Current derating and thermal limits
That's a shallow derating curve — you don't lose a full breaker size until well above typical panel ambient. Maximum power loss is 11 W, which matters for heat buildup in a densely packed enclosure; account for it when sizing ventilation.
Dimensions are 76.2 mm wide, 130 mm tall, 70 mm deep — standard 3-pole MCCB footprint for Siemens SENTRON 3VA frames. Mounts on DIN rail or direct panel. The undervoltage release adds a control-wire connection; verify wiring polarity per the terminal marking. No communication module or ground-fault monitoring on this variant.