The Allen-Bradley 140U-K3D3-D30 Molded Case Circuit Breaker is a UL-489 listed circuit breaker that is designed to provide overcurrent protection to a wide range of industrial control panel applications. It belongs to the 400 Amos rated K-Frame circuit breaker family and it comes with a compact design that makes it suitable for applications that require minimal panel space. The 140U-K3D3-D30 Circuit Breaker is suitable for back-feeding (at around 240, 480, and 277 Volts AC, and it can be used in applications like the feeder circuits (brach circuit application), control circuits, heating, air conditioning and refrigeration (HACR), and the high-intensity-discharge circuit applications.

The 140U-K3D3-D30 Circuit Breaker has a 3-phase supply voltage rating of 480 Volts AC and a maximum trip current rating of 300 Amps. It has a breaking capacity of 35 Kilo-Amps (KA) at 480 Volts AC input voltage and a UL rated insulation voltage of 600 Volts. This device has a lifespan (mechanical) of about a hundred thousand operations and an electrical lifespan of around ten thousand operations. The 140U-K3D3-D30 Circuit Breaker has protection unit that consists of a fixed thermal and an adjustable magnetic strip. This trip unit provides fixed overload protection via a bimetal element that actuates the trip with a delay based on the set trip value, and it offers instantaneous trip action via an electromagnetic device with adjustable trip ratings. The 140U-K3D3-D30 Circuit Breaker has a fixed thermal rating of 300 Amps and an adjustable magnetic trip rating between 1500 Amps and 3000 Amps. It has an open style design, and it comes with an end cap bolt-on connector.