What it is and what it does
The Siemens 3VA1150-5EF36-0BC0 is a SENTRON 3VA-series molded case circuit breaker (MCCB) for line protection, rated 50 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. It is a 3-pole unit with an undervoltage release (UVR) and two auxiliary switches (HQ type) built in. The TM240 release provides fixed thermal and magnetic trip settings for overload and short-circuit protection in distribution panels and motor control centers. The undervoltage release (UVR) trips the breaker when supply voltage drops below a threshold, protecting downstream equipment from brownout conditions.
Breaking capacity — the real-world headroom
This MCCB delivers 187 kA breaking capacity at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. These figures mean it can safely interrupt fault currents up to those levels without welding contacts or rupturing the case — critical for high-fault installations like large transformer secondaries or industrial feeder panels. The 187 kA at 240 V is among the highest in the 3VA line for a 50 A frame, giving substantial selectivity headroom upstream of downstream breakers. At 690 V the 17 kA rating still covers most industrial motor branch circuits.
Thermal derating and ambient temperature
Rated continuous current holds at 50 A from 40 °C through 50 °C ambient. Above that, it derates linearly: 48 A at 55 °C, 47 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. For a panel running hot near the 70 °C operating maximum, expect to lose 5 A of headroom — factor that into your load schedule. The operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. The IP40 front protection means it's suitable for dry indoor panels but not washdown areas.
Lifecycle and sourcing reality
The integrated auxiliary trip is order code 3VA9608-0BB11 — a separate line item if you need a spare or replacement for that subassembly.
Physical fit and panel integration
Dimensions: 130 mm height, 76.2 mm width, 70 mm depth. The 76.2 mm width (3-inch footprint) is standard for 3-pole MCCBs in the 3VA frame size — it mounts on a DIN rail or panel-mount baseplate. Verify the depth clearance in your enclosure: 70 mm plus wiring space for the line and load lugs.