What it is and what it does
The Siemens 3VA1150-4EF36-0AG0 is a 3-pole SENTRON molded case circuit breaker (MCCB) rated 50 A at 40 °C, designed for line protection in commercial and industrial distribution panels. It carries a 121 kA interrupting capacity at 240 VAC and 75.6 kA at 415 VAC, with a TM240 thermal-magnetic release that combines a thermal bimetal for overload protection and a magnetic coil for short-circuit response. Rated insulation voltage is 800 V, and maximum power loss is 14.6 W.
Breaking capacity and selectivity
The 121 kA at 240 VAC is the headline SCCR figure — enough for high-fault utility feeds in North American panels. At 415 VAC it still holds 75.6 kA, dropping to 52.5 kA at 440 VAC and 11.9 kA at both 500 VAC and 690 VAC. For a 50 A frame, these numbers mean it can be used as a main or feeder breaker in most industrial switchboards without needing a current-limiting upstream device. The thermal-magnetic TM240 release coordinates cleanly with downstream miniature breakers in a selective scheme — the magnetic trip is fixed, so verify the instantaneous threshold against the let-through of the downstream devices during coordination study.
Current ratings across temperature
Rated current holds at 50 A from 40 °C through 50 °C. At 55 °C it derates to 49 A, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. Ambient temperature inside the enclosure matters — if the panel runs hot, the continuous current capability drops. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Auxiliary switching and monitoring
This variant ships with one auxiliary switch and one trip alarm switch. The auxiliary switch signals the breaker's open/closed position; the trip alarm switch signals when the breaker has tripped on fault — useful for remote status monitoring in a PLC or SCADA system. It has a trip indicator and no undervoltage release or communication function. Ground-fault monitoring is not included. The supplied basic switch is order code 3VA11504EF360AA0.