What this 50 A MCCB delivers on a mill floor
The Siemens 3VA1150-5EE42-0AA0 is a SENTRON molded case circuit breaker rated 50 A at 40 °C with a TM220 thermal-magnetic release. Four poles give you the isolation and overcurrent protection a three-phase line needs plus a switched neutral — common on European-sourced panels where a solid neutral isn't assumed. The 187 kA breaking capacity at 240 V means this breaker can sit upstream of a fault without the arc flashing back into the bus; at 415 V it still clears 121 kA, so it handles the high-fault conditions you get near a mill's main step-down transformer. Rated insulation voltage is 800 V, which keeps the internal creepage distances adequate for 690 V line-to-line systems — common in European industrial networks and some North American 600 V class installations. The TM220 release gives a fixed thermal pickup and magnetic trip that's factory-set; no field-adjustable dials, so what you order is what protects the feeder.
Thermal derating and panel fit
At 40 °C the breaker carries a full 50 A. That holds steady through 50 °C; at 55 °C it derates to 49 A, and at 70 °C it's 45 A. If the panel sits near a dryer section or a hot motor control center, the 45 A floor at 70 °C still gives you headroom for a 40 A continuous load. The 14.6 W maximum power loss means the heat it dumps into the enclosure is modest — a standard steel enclosure with passive ventilation handles it, but if you're stacking several breakers in a tight row, check the cumulative dissipation against the enclosure's rating. Dimensions are 70 mm deep, 101.6 mm wide, 130 mm high. The 4-inch width (101.6 mm) fits a standard 4-pole MCCB footprint on the DIN rail or bolted bus. Front protection is IP40 — no water ingress protection, so keep it inside a panel rated for the environment. The operating range is -25 °C to 70 °C; storage range is -40 °C to 80 °C, which covers a cold warehouse or a hot shipping container without issue.
Selectivity and coordination
The 187 kA at 240 V and 121 kA at 415 V are the ultimate breaking capacities — the breaker clears a fault at those levels once and must be replaced afterward. For selectivity studies, the TM220's magnetic trip is fixed, so you coordinate by choosing a downstream breaker with a lower magnetic threshold. The 800 V rated insulation voltage gives you the dielectric margin for 690 V systems, but the actual breaking capacity at 690 V drops to 17 kA — that's still adequate for most 690 V motor branch circuits, not for a main tie.