Siemens 3VA1150-5EF32-0AB0 SENTRON MCCB, 50A, 187kA at 240V

The Siemens 3VA1150-5EF32-0AB0 is a SENTRON molded case circuit breaker (MCCB) built for line protection in distribution panels and industrial switchboards. It carries a 50 A continuous rating at 40 °C ambient and holds that rating steady up to 50 °C — no derating needed in a warm enclosure — then drops to 45 A at 70 °C. That thermal curve means you can size it for a 50 A feeder and still have headroom if the panel runs hot. Breaking capacity is what sets this MCCB apart: 187 kA at 240 VAC, 121 kA at 415 V, and 75.6 kA at 440 V. Those numbers tell you it's designed for high-fault locations — think transformer secondaries or large motor control centers where available fault current is serious. At 500 V and 690 V it still handles 17 kA, which covers most industrial 480/600 V services. It's a 3-pole unit with a TM240 thermal-magnetic release — fixed thermal and magnetic trip settings, no adjustment dial. The overload curve is set for line protection (cable/feeder), not motor protection, so don't use it as a motor starter protector unless you have separate overloads downstream. Insulation voltage is rated 800 V, so it's comfortable on 690 V systems with margin. Power loss runs 14.6 W maximum at rated load — negligible for thermal calculations in most enclosures, but worth noting if you're packing multiple breakers in a small dead-front panel. Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — standard 3-pole MCCB footprint that fits most Siemens SENTRON mounting bases and busbar systems.