The 140U-JD3D3-D17 circuit breaker from Allen-Bradley is an advanced molded case circuit-breaker in a compact JD-frame enclosure. The circuit breaker's continuous current rating is 175 Amps. The 140U-JD3D3-D17 circuit breaker supports both thermal and magnetic tripping through the incorporation of a thermal-magnetic trip module. The thermal trip thresholds are fixed. However, the magnetic trip thresholds are configurable and can be set at 875 Amps, 980 Amps, 1090 Amps, 1200 Amps, 1310 Amps. 1420 Amps, 1530 Amps, 1640 Amps, and 1750 Amps. When used as a NEMA starter size 4 device, the 140U-JD3D3-D17 circuit breaker supports 40 Horsepower of output at 200 Volts AC, 50 Horsepower of output at 230 Volts AC, and 100 Horsepower of output at 460 Volts AC. When used as a NEMA starter size 5 device, the breaker supports 125 Horsepower of output at 575 Volts AC.

The 140U series to which the 140U-JD3D3-D17 circuit breaker belongs has several key features, including a wide interrupting/breaking capacity range, a compact circuit breaker design, common accessories, support for electronic trip units, and a wide range of operating mechanisms. Key features of the 140U family of breakers are simplified panel design, panel space savings, and flexibility due to the availability of field-installable breaker accessories. The 140U-JD3D3-D17 circuit breaker is a 3-pole breaker with 30 to 39 kiloamps breaking capacity/interrupting rating at 480 Volts AC. Allen-Bradley strongly recommends the disconnection of the power supply to systems where the 140U-JD3D3-D17 circuit breaker is either being installed, serviced, or tested. Failure to follow this recommendation can lead to serious consequences, including damage to the associated electrical equipment and injury to the workers.