The 140U-K3D3-D12 UL listed Molded Case Circuit Breaker is a molded case circuit breaker from the Allen-Bradley Bulletin 140U circuit breaker family that is designed to protect industrial control panel applications from thermal overload and short-circuit conditions. Like all Bulletin 140U circuit breakers, the 140U-K3D3-D12 Circuit Breaker is designed around a compact footprint, making it ideal for applications even in limited panel space. The 140U-K3D3-D122 Circuit Breaker supports back-feeding at 240 Volts AC and 480 Volts AC and it is ideal for the control circuit, feeder circuit, HACR (heating, air conditioning, and refrigeration), and high-intensity discharge applications. The 140U-K3D3-D12 Circuit Breaker is rated at 480 Volts AC (3-phase) and it has an operating voltage range between 230 Volts AC to 690 Volts AC. It has a trio current rating of 120 Amps, and a maximum interrupt rating of 35 Kilo-Amps at 480 Volts AC.

The 140U-K3D3-D12 Circuit Breaker has a maximum impulse withstand of 6 Kilo-Volts, and it also has an insulation voltage rating of 750 Volts. It has a mechanical lifespan of 100,000 operations and an electrical life cycle of around 10,000 operations. The 140U-K3D3-D12 Circuit Breaker has a fixed thermal/adjustable magnetic trip unit comprising an actuating mechanism, contacts, a lever, and a thermal/magnetic strip. It provides fixed thermal overload protection by using a bimetal heat element that deflects and actuates contact opening based on the set overload value and it also uses an electromagnetic device with an adjustable instantaneous trip that actuates the instantaneous trip action upon reaching the set trip value. The 140U-K3D3-D12 Circuit Breaker comes with end cap bolt-on terminals as standard line and load end terminals but a terminal lugs kit must be ordered separately.