The Siemens SENTRON 3VA1150-4EF36-0BH0 is a 3-pole molded case circuit breaker (MCCB) rated 50 A at 40 °C, designed for line protection in industrial distribution panels. It carries a 121 kA interrupting capacity at 240 V AC, dropping to 75.6 kA at 415 V and 52.5 kA at 440 V — figures that tell you this breaker handles high-fault locations like transformer secondaries or main feeders without cascading upstream.
Breaking capacity and selectivity
The 121 kA SCCR at 240 V is the headline number, but the real-world fit depends on the system voltage. At 415 V the breaker still clears 75.6 kA, and at 440 V it manages 52.5 kA — enough for most North American 480Y/277 V and European 400 V distribution. At 500 V and 690 V it holds 11.9 kA, so it stays viable for 690 V industrial networks with moderate fault levels. The rated insulation voltage is 800 V, which covers the 690 V class comfortably.
Current rating and thermal derating
Rated 50 A continuous at 40 °C ambient. The thermal curve holds flat to 50 °C, then derates to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If your panel ambient runs above 50 °C, size the load accordingly — the breaker won't trip early, but you lose headroom. Power loss at full load is 17.1 W maximum, which matters for enclosure heat calculations in a sealed cabinet.
Auxiliary and release configuration
Factory-fitted with an undervoltage release (UVR) and a 2-auxiliary-switch plus 1-trip-alarm-switch (HQ) block. The UVR ensures the breaker drops out on voltage loss — typical for safety circuits or motor feeder coordination. The trip alarm gives a dedicated signal for remote fault indication, separate from the aux position feedback. No ground-fault monitoring on this variant.