Siemens U01JLD6 Undervoltage Circuit Breaker Trip Unit

Siemens U01JLD6 undervoltage release is a 120 V AC control accessory for Sentron molded-case circuit breakers that trips the main breaker when the monitored voltage drops below a preset undervoltage threshold. This 1‑UVR configuration provides a single undervoltage trip for use with Siemens JD/SJD, LD/SLD, and LMD frame breakers in the Sentron family, and it uses a 120 VAC control input to actuate the tripping mechanism. For circuits that require additional signaling, Siemens offers UVR variants such as U01JLD62A and U01JLD62AA that pair an undervoltage trip with auxiliary switches on compatible frames. Common applications include industrial control panels and equipment where an undervoltage condition must force disconnection to protect downstream devices like motors and relays, delivering coordinated protection within the overall protection scheme. Because it is an accessory rather than a standalone breaker, installation requires pairing with a compatible molded-case breaker and adherence to Siemens installation instructions for JD, LD, or LMD frame systems.