Over-temperature is detected by a normally-closed-low temperature switch mounted on the stator.
The ATC Diversified Submersible Pump Monitor is a specialized control for monitoring the shaft seal and stator temperature of a submersible pump motor. Seal leakage is detected by either a resistive float switch or a pair of conductive probes installed in the seal cavity. The over-temperature function incorporates a bistable relay that retains its position during power failures..