Siemens SENTRON 3VA1112-5EF32-0KC0 — 125 A MCCB for Line Protection
The Siemens SENTRON 3VA1112-5EF32-0KC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection at 125 A continuous, with a thermal-magnetic TM240 overcurrent release and an integrated shunt trip (STL) for remote tripping. It carries 2 auxiliary switches (HQ configuration) for status feedback to a PLC or panel indicators. Breaking capacity is the headline here: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V. That 187 kA figure at 240 V means it can safely interrupt very high fault currents typical of transformer secondaries or large motor banks — essential for selective coordination downstream of a 2000 kVA transformer without cascading failure. Rated insulation voltage is 800 V, so the breaker is rated for 690 V AC systems with margin. Power dissipation maxes at 28.1 W — factor that into enclosure thermal calculations when packing multiple breakers in a panel.
Panel Fit and Mounting
The 3VA1112-5EF32-0KC0 measures 130 mm high, 76.2 mm wide, and 70 mm deep — a standard 3-pole MCCB footprint that drops into most SENTRON mounting plates and DIN-rail adapters without panel modification. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The current derating curve starts above 55 °C — at 55 °C it still carries 122 A, at 70 °C it derates to 114 A. For a 125 A nominal load in a 50 °C panel, no derating is needed.
Auxiliary Release and Switching
The shunt trip (STL) design allows remote tripping via a control signal — typical for emergency-stop circuits or supervisory shutdown. The 2 auxiliary switches (HQ version) provide normally-open and normally-closed contacts for status monitoring without additional interposing relays.