MCCB for 640 A feeder and motor protection
The Siemens SENTRON 3VM1140-5MH32-0AA0 is a 3-pole molded case circuit breaker rated for 640 A maximum, with a TM120M thermal-magnetic overcurrent release. It breaks up to 187 kA at 240 V AC and 121 kA at 415 V AC — enough headroom for high-fault panelboards and transformer secondaries. Rated insulation voltage is 800 V, operating voltage 690 V AC, so it covers 480/600 V distribution without derating on voltage. Thermal derating is tight: 40 A continuous through 50 °C, dropping only to 37 A at 70 °C. That means the breaker holds its rating across most panel ambient conditions without upsizing.
Dimensions are 70 mm deep, 76.2 mm wide, 130 mm tall — a standard MCCB footprint for DIN-rail or panel-mount installation. IP40 front protection suits enclosed panel use; not rated for washdown environments.