The Allen-Bradley 140U-JDTD3-D25-M circuit breaker is a thermal-magnetic circuit breaker that has been designed to operate with motors and different kinds of industrial equipment that require branch circuit, overload, and short circuit protection. It has been manufactured and designed by Alen-Bradley/Rockwell Automation. This circuit breaker includes a thermal and magnetic trip unit that consists of the use of metal bars that receive heat and a magnet. Once the Allen-Bradley/Rockwell Automation 140U-JDTD3-D25-M thermal-magnetic circuit breaker has detected an abnormal condition, it will send a signal to its three poles to perform the tripping action and stop the current flow into the circuit or equipment. These three poles are connected so these poles can all act at the same time.

Once a tripping action has been performed and the condition that caused this action has been cleared, the Allen-Bradley/Rockwell Automation 140U-JDTD3-D25-M thermal-magnetic circuit breaker can be set back into operation. This breaker can work non-stop once current faults or conditions are correctly cleared. The breaker and the motor need to be compatible when it comes to the voltage and amperage ratings. The Allen-Bradley/Rockwell Automation 140U-JDTD3-D25-M thermal-magnetic circuit breaker belongs to the J Frame series and it operates with a current rating of 225 Amps and a voltage rating of 480 Volts. The current rating of the drive can vary according to the voltage level. It is recommended to install the breaker in a proper enclosure if the proper environmental conditions are not met. These conditions can include the presence of hazardous materials around the breaker and extreme temperatures. The maximum ambient air temperature that is permissible without derating the breaker is 40 degrees Celsius.