Inhouse product
These units are small electronic control modules that mount inside electrical panels and monitor the three incoming power lines. They typically include:
Input leads for each phase motor supply (L1, L2, L3)
Low‑voltage control terminals (C & Y/Y‑OUT for 24 V control)
LED indicators showing power ON and fault condition
Single relay output that opens on fault to protect equipment such as compressors and motors from damage caused by incorrect phase conditions.
The devices are often epoxy‑encapsulated for rugged HVAC/R environments and rated for wide line voltage ranges (190‑600 VAC typical).