MCCB for line protection — 50 A, 3-pole, with UVR and aux switches
The Siemens SENTRON 3VA1150-5EF36-0CC0 is a 3-pole molded case circuit breaker (MCCB) designed for line protection, rated 50 A at 40 °C with a thermal derating curve that holds 50 A through 50 °C, then steps down to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C — so in a 65 °C panel ambient the breaker still carries 46 A continuously without tripping. Interrupting capacity is 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 — the 187 kA figure at 240 V means this breaker can safely clear a fault on a high-capacity 240 V distribution transformer without upstream fuses needing to clear first.
Built-in undervoltage release and auxiliary switch complement
It also carries two auxiliary switches HQ (high-rupturing-capacity type) for remote status indication — one normally-open and one normally-closed contact pair that can be wired into a PLC input module or a panel lamp circuit to confirm the breaker position. The basic switch ordered separately is 3VA11505EF360AA0 — the factory-assembled variant here avoids field-fitting the UVR and aux switches, which saves panel-build labour and eliminates the risk of mis-wiring the release coil.
Thermal management and panel fit
Maximum power loss is 17.1 W at rated load — for a 3-pole breaker in a sealed enclosure this heat must be accounted for in the thermal budget; the derating curve above 55 °C already reflects internal heating. Dimensions are 130 mm height, 76.2 mm width, and 70 mm depth (2.76 in).