The 140U-H6C3-D12-A-MT circuit breaker is a thermal-magnetic circuit breaker with a double protection mechanism that consists of a fixed-thermal and a fixed-magnetic mechanism. These two protection mechanisms employ two bimetal bars that get heated by the current and by the use of magnets. These magnets have an interrupting action of up to 60 kiloamps. This circuit breaker has been designed by Allen-Bradley and it has been included in the 140U series of motor protection devices, specifically the Frame H product line. The Allen-Bradley 140U-H6C3-D12-A-MT thermal-magnetic circuit breaker comes with three poles that are connected with each other and that are responsible for performing the tripping action on the breaker once an irregular current flow has been detected. The breaker can be restarted after clearing the fault condition.

The ambient operating temperature range of the Allen-Bradley 140U-H6C3-D12-A-MT thermal-magnetic circuit breaker goes from –8.9 to 60 degrees Celsius. It can be used without any problem at temperatures of up to 75 degrees Celsius if it is properly derated. The Allen-Bradley 140U-H6C3-D12-A-MT thermal-magnetic circuit breaker can be installed in a cabinet and all of its connections must be suitable for operations at up to 75 degrees Celsius. The breaker provides short-circuit protection to motors, meaning that when exposed to excessive currents, the breaker will stop this current flow before it can cause any damage to the motor or equipment system. This breaker comes with one auxiliary contact, one alarm contact, and a shunt trip. The operational voltage of the drive goes from 230 to 690 Volts AC and from 24 to 240 Volts DC. This breaker comes with fuses and mini circuit breakers as back-up protection mechanisms.