Siemens SENTRON 3VA1120-6EF32-0BC0 — 20 A MCCB with 220 kA interrupting capacity
The Siemens SENTRON 3VA1120-6EF32-0BC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 20 A at 40 °C and a massive 220 kA breaking capacity at 240 V — that SCCR headroom means it can sit at the service entrance or on a high-fault panel feeder without cascading upstream. Rated insulation voltage is 800 V, and the interrupting ratings scale down with voltage: 154 kA at 415 V, 121 kA at 440 V, and 17 kA at 500 V and 690 V — so it stays effective on 480 V or 600 V class systems where fault current can still hit tens of kiloamps. This MCCB ships with an integrated undervoltage release (UVR) and two auxiliary switches (HQ design), which means it can be wired into a safety circuit that drops the breaker on loss of control voltage, and the aux contacts report position back to a PLC or status lamp — no external add-on block needed for basic signaling.
Thermal derating and panel fit
Current rating holds flat at 20 A from 40 °C up to 55 °C, then derates to 19 A at 60 °C through 70 °C — so in a warm enclosure near the top of the ambient range you lose only 1 A, not a full frame size. Dimensions are 76.2 mm wide (3 in), 130 mm tall (5.12 in), and 70 mm deep (2.76 in) — a standard 3-pole MCCB footprint that fits a DIN-rail or panel-mount backplate without surprises. Maximum power loss is 14.5 W — modest enough that ventilation slots in a typical steel enclosure handle the heat without forced air, but worth checking if the breaker is packed next to other high-dissipation gear.