UCON-A120B-W(INST) Controller; AC 100 – 120V Inst. trip (Time delay adj.), b-contact

This is the device that automatically trips the breaker when the circuit voltage drops below the nominal voltage, and comprises a UVT coil and UVT controller.
time: INST (0.2 sec or less)/0.25 sec/0.5 sec/ 0.8 sec/1.0 sec/1.5 sec/3 sec.