The Allen-Bradley 140G-KTF3-D40 trip unit is a general-purpose circuit breaker trip unit from the 140G molded case circuit breaker series that is designed for the efficient and cost-effective protection of branch and main circuit applications. The 140G-KTF3-D40 trip unit is a thermal-magnetic trip unit for the K Frame molded case circuit breaker series, and it features adjustable thermal and magnetic trip ratings to accommodate wider applications. The 140G-KTF3-D40 trip unit is a 400 Amps rated trip unit (it is a protection unit only), and it is suitable for a circuit with a maximum operating voltage rating of 600 Volts AC. This trip unit has a thermal trip rating that is adjustable from 280 Amps to 400 Amps, and its magnetic trip rating is also adjustable from 2000 Amps to 4000 Amps to suit a wider application range.

The 140G-KTF3-D40 trip unit is designed with an electromagnet trip element that provides a magnetic field that is proportional to the line current, thus tripping the breaker’s contacts when the line current exceeds the set tripping value. It also has a bimetallic thermal trip element that provides a thermal tripping action by using the proportional relationship between current and heat, thus tripping the breaker’s contact when the ambient temperature reaches the set value. The 140G-KTF3-D40 trip unit has a mechanical lifetime rating of 20,000 operations and a mechanical lifetime rating of up to 4000 operations at 415 Volts AC. This trip unit has a rated withstand voltage value of 8.0 KiloVolts, and a rated insulation voltage value of 800 Volts. The 140G-KTF3-D40 trip unit is rated 80% efficient at 40 degrees Celsius ambient temperature, and it will begin to de-rate at a temperature above this value. Like every 140G circuit breaker and circuit breaker accessory, the 140G-KTF3-D40 trip unit is CCC, CSA, CE, and UL certified.