What this MCCB carries and where it fits
The Siemens SENTRON 3VA1112-6MH32-0BC0 is a 3-pole molded case circuit breaker (MCCB) rated 125 A at 40 °C, with a breaking capacity of 220 kA at 240 V and 154 kA at 415 V — numbers that put it in the high-interrupting class for industrial distribution panels where fault currents can hit those levels. It ships with an undervoltage release (UVR) and two HQ auxiliary switches built in, so it's ready for a safety circuit that drops the breaker when control voltage is lost, and for remote status feedback without adding separate contact blocks. The insulation voltage is rated 800 V, which covers 690 V line-to-line systems with margin — common in heavy industrial motor control centres.
Breaking capacity across voltages — what matters for selectivity
At 240 V this breaker clears 220 kA; at 415 V it's 154 kA; at 440 V it drops to 75.6 kA; and at 500 V and 690 V it holds at 7.5 kA. The steep drop above 440 V means you need to check the available fault current at the point of installation — if your system runs 480 V or 600 V class, the 7.5 kA rating may force a larger frame or a current-limiting fuse upstream.
Current derating and thermal limits
Rated 125 A up to 50 °C; at 55 °C it's 122 A, at 60 °C it's 120 A, at 65 °C it's 117 A, and at 70 °C it's 114 A. If your panel ambient runs hot, you lose about 1 A per 5 °C above 50 °C — factor that into the load calculation so you don't nuisance-trip on a summer afternoon. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The storage limit is wider because it's not under load — fine for warehousing spares. Maximum power loss is 30.6 W — that's the heat it dumps into the enclosure. If you're packing several of these in a small panel, add that to your thermal budget.
Panel fit and mounting
Dimensions: 130 mm high, 76.2 mm wide, 70 mm deep. That's a 3-inch wide footprint — standard for a 3-pole MCCB in this class. Bolts into a panel or mounts on a DIN rail adapter; the depth leaves room for rear-connected bus bars.