The 140U-J6D3-D20 circuit breaker is a J Frame breaker from Allen-Bradley/Rockwell Automation. It is a Series B device with a current rating of 200 Amps. The breaker has 3 poles and it operates with an input supply voltage of 480 Volts AC. The operating frequency of the breaker is 60 Hertz with fixed thermal and adjustable magnetic trip options. It is a current limiting breaker device and it can be used with both single-phase and three-phase applications. The 140U-J6D3-D20 circuit breaker comes with an electrical switch that can help protect a circuit against overload and short circuit conditions. The basic function of the breaker is to break the current flow when an unusual condition is detected. A circuit breaker comprises contacts, a lever, an actuator mechanism, line and load terminals, and a thermal-magnetic trip. When an overcurrent condition takes place, it heats the bimetallic element in the breaker which changes its shape which in turn releases the lever and trips the circuit breaker and interrupts the circuit.

The Allen-Bradley 140U-J6D3-D20 circuit breaker can be bolted into place by using a bolt-on mounting base. It comes with a complete non-interchangeable trip and a long-time instantaneous trip function. The breaker can interrupt for 65 kA at 480 Volts AC. The breaker works with both a single-phase and a three-phase power supply. The power supply is connected to a breaker through a line terminal which is in the top part of the circuit breaker. A push-to-trip feature is available in the 140U-J6D3-D20 circuit breaker which is manually used to set the trip. This circuit breaker variant is widely used in the industrial sector for protecting machine circuits.