The 140U-K6D3-D12 Molded Case Circuit Breaker is a UL489 listed 3-pole circuit breaker form the 400 Amps rated K-Frame breaker family that is built to provide thermal overload and short-circuit protection to industrial control panel applications. This circuit breaker together with other Bulletin 140U circuit breakers offer higher interrupting ratings within a compactly designed package, and they are suitable for back-feeding at 240/480 Volts AC. The 140U-K6D3-D12 Circuit Breaker is designed for feeder circuit applications such as branch circuit protection, small cabinets, and distribution panel applications, control circuit applications such as control transformers and power supply applications, HACR applications, and high-intensity discharge applications. The 140U-K6D3-D12 Circuit Breaker has a maximum interrupting rating of 100 Kilo-Amps at 480 Volts AC and a maximum trip rating of 120 Amps. It is rated at 480 Volts AC and it is suitable for a circuit with a 240 to 600 Volts AC operating voltage range.

The 140U-K6D3-D12 Circuit Breaker has an insulation voltage rating of 70 Volts and a maximum voltage withstand rating of 6 Kilo-Volts. The 140U-K6D3-D12 Circuit Breaker comes with both a magnetic and thermal trip unit that offers thermal overload and instantaneous over current protection. The thermal trip unit consists of a bimetallic element that provides a trip action based on the fixed current value and its magnetic trip unit uses an electromagnetic device with an adjustable trip rating for instantaneous trip action. The 140U-K6D3-D12 Circuit Breaker has a fixed thermal rating of 125 Amps and an adjustable magnetic current rating between 625 Amps and 1250 Amps. The 140U-K6D3-D12 Circuit Breaker has standard screw (bolt-on) terminals, and it comes with an open type of enclosure design. It has a rated operating temperature range of -8 to 60 degrees Celsius, and it has a maximum operating height of 2000 meters.