Transformer circuit breaker MS132-T with thermal and electromagnetic protection represents the compact and powerful series with high short-circuit breaking capacity for transformer protection up to 25 A with a module width of 45 mm. With this device, the primary-side transformer rated current is thermally monitored by setting on the current scale. The short-circuit is triggered when 20 times the device rated current occurs. The temperature-compensated device has a rotary handle operation with a clear switch position indicator I/TRIP/0. In addition, MS132-T has a short-circuit indicator. The rotary handle can be directly locked in the 0 position using a padlock. Auxiliary, signal and short-circuit signaling contacts as well as undervoltage and shunt current releases can be installed without tools. 1-phase feed-in blocks up to 25 mm² and phase connectors support the wiring of 1-phase transformers.