What this MCCB delivers — and where the rating matters
The Siemens SENTRON 3VA1120-5EF36-0CA0 is a 3-pole molded case circuit breaker (MCCB) rated for 20 A continuous current at up to 50 °C ambient — no derating needed until you cross that threshold. Above 55 °C it steps down linearly to 18 A at 70 °C, which is the operating maximum. The headline number here is the interrupting capacity: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V. That 187 kA at 240 V means it can safely clear a fault of that magnitude without welding contacts or rupturing the case — critical for high-fault installations like transformer secondaries or large motor control centers where available fault current can exceed 100 kA. The TM240 thermal-magnetic release handles the overload and short-circuit protection in one package; no separate trip unit to order. The undervoltage release (UVR) is integrated, so if control voltage drops, the breaker trips — a standard requirement for safety circuits that need to drop power on loss of pilot voltage.
Panel integration and physical fit
The 3VA1120-5EF36-0CA0 measures 76.2 mm wide, 130 mm high, and 70 mm deep — a 3-pole MCCB footprint that fits standard Siemens SENTRON panelboards and distribution blocks. IP40 on the front means it's protected against tools and wires >1 mm, but not against water ingress; mount inside a rated enclosure for washdown or outdoor environments. The integrated undervoltage release (UVR) is wired to the control circuit; no auxiliary contacts are included, so if you need status feedback to a PLC or SCADA, plan for the separate 3VA9608-0BB24 auxiliary trip accessory. No communication module, no phase-failure detection — this is a straight line-protection breaker, not a smart device.
Selectivity and coordination note
The 187 kA breaking capacity at 240 V gives headroom for selective coordination with downstream breakers. The TM240 release's thermal curve is fixed. The 15,000-cycle mechanical endurance is adequate for distribution duty.