It is a dedicated accessory — not a standalone breaker — and mounts directly onto the breaker via snap-on fastening, occupying the accessory slot on the left side of the 3RV2 frame. The coil is rated 208 V AC at 60 Hz, so it holds in when the control supply is healthy and releases the breaker mechanism if that voltage falls off, preventing an automatic restart on brownout or phase loss. This is the standard undervoltage protection scheme for motor circuits that must not re-energize without a deliberate reset.
The release snaps onto 3RV2 breakers in frame sizes S00, S0, S2, and S3. At 18.5 mm wide and 68 mm deep, it adds minimal DIN-rail footprint beyond the breaker's own width. Screw terminals accept the control wiring directly; no separate base or adapter is needed.