Siemens 3UN2100-0CN7 Industrial Automation Control Module

Siemens 3UN2100-0CN7 is a thermistor-based motor protection relay that monitors motor-winding temperature with an integrated PTC sensor and trips a single SPDT contact when an over-temperature condition is detected. The unit features IP20 protection, auto reset, and monostable operation with two LED indicators for status, plus a changeover contact rated for AC 220–240 V at 50/60 Hz. Measuring about 4.0 in x 4.0 in x 1.0 in (10.2 cm x 10.2 cm x 2.5 cm) and weighing roughly 0.2 kg, the compact module is designed for panel mounting alongside Siemens protection devices and is a legacy part with documented end-of-life/PLM status in reseller listings, commonly used in motor-protection schemes to guard against overheating through thermistor-based sensing.