The Allen-Bradley 140U-K6D3-D40 Circuit Breaker is a K-Frame Molded Case Circuit Breaker (MCCB) with a rated current of 400 Amps, a supply voltage of 480 Volts, an interrupting rating of 65 kA, and a 3-pole configuration. It offers fixed thermal/adjustable magnetic trip protection. In general, it has an Ampere Interrupting Capacity (AIC) rating of 65 kA at 480 Volts. It has a maintenance mode that allows the users to turn on a lower current trip threshold for a limited time, especially when they are operating on the panels and doing inspection or maintenance applications. The 140U-K6D3-D40 Circuit Breaker reacts faster if there is a current increase during the maintenance mode. It is used in circuit protection devices such as switchboards, panelboards, individual enclosures, and bus-bar trunking tap-offs.

The Allen-Bradley 140U-K6D3-D40 Molded Case Circuit Breaker is factory assembled. It has factory-installed internal control modules which are both left and right side-mounted. The left side-mounted modules include the Undervoltage Release (UVT) and Shunt Trip (SNT), whereas the right side-mounted modules are the Auxiliary Contact (AX), Alarm Contact (AL), and Auxiliary/Alarm Contact (AX/AL) combination modules. The 140U-K6D3-D40 circuit breaker has a mechanical lifespan of 20,000 operations or 120 operations per hour. It also has an electrical life of 415 Volts AC with 7000 operations at 400 Amps and 5000 operations at 630 Amps and at 60 operations per hour. It has a maximum ambient temperature of 40 degrees Celsius (104 degrees Fahrenheit) without derating and a storage temperature range of -40 to 80 degrees Celsius (-40 to 176 degrees Fahrenheit). The circuit breaker has dimensions of 140 x 108.5 x 205 millimeters.