50 A MCCB with shunt trip for line protection
The Siemens 3VA1150-5EF32-0KA0 is a SENTRON 3-pole molded case circuit breaker rated 50 A at 40 °C, designed for line protection in distribution panels. Its 187 kA breaking capacity at 240 V AC handles high-fault-current scenarios typical at the service entrance or main feeder, giving the upstream transformer or generator a clean fault-clearing point without cascading through downstream gear. The integrated shunt trip release (STL) allows remote tripping via a control signal — useful for emergency-off circuits or interlocking with a fire-alarm panel. The breaker carries a TM240 thermal-magnetic overcurrent release, so it responds to both sustained overloads (thermal) and short-circuit events (magnetic) with a fixed time-current curve.
Breaking capacity across voltage levels
The interrupting rating drops as system voltage rises: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V. For a 400 V class panel (common in European industrial distribution), the 121 kA rating at 415 V provides ample headroom for most transformer-fed installations, but the steep drop to 17 kA at 500 V means this breaker is not suited for 480 V or 600 V systems where the available fault current exceeds that threshold.
Thermal derating and ambient temperature
The breaker holds its full 50 A rating up to 50 °C ambient, then derates to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. In a sealed, uncooled enclosure — say a panel mounted near a furnace line or in a Middle East substation — the 45 A floor at 70 °C still leaves margin for a 40 A continuous load, but a design pushing 48 A at 60 °C is at the limit. The operating range spans -25 °C to 70 °C; storage from -40 °C to 80 °C.
Physical fit and panel integration
Dimensions: 130 mm height, 76.2 mm width (3 in), 70 mm depth (2.76 in). The 3-pole footprint matches the standard SENTRON 3VA mounting pattern.