The Siemens 3VA1112-6EF36-0AH0 is a SENTRON molded case circuit breaker (MCCB) rated 125 A at 40 °C, 3-pole, with a TM240 thermal-magnetic overcurrent release. It's designed for line protection in distribution panels — the interrupting rating of 220 kA at 240 V means it can clear a bolted fault at that level without rupturing, which is the kind of headroom you want on a high-capacity bus or transformer secondary.
Ratings and what they mean for fit
The 125 A continuous rating holds across 40 °C to 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. That's a shallow derate curve — you can run it near its nameplate in a warm enclosure without losing much margin. The interrupting rating steps down with voltage: 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. At 480 V systems (common in North America) it's still well above typical available fault currents. Insulation voltage is rated 800 V, so it's comfortable on 690 V line-to-line networks.
Physical fit and integration
The 3VA1112-6EF36-0AH0 measures 130 mm high, 76.2 mm wide, and 70 mm deep — a 3-pole frame that fits standard SENTRON mounting feet and busbar adapters. It carries 2 auxiliary switches plus a trip alarm switch (HQ design) for remote status indication. No undervoltage release or ground-fault monitoring on this variant; those are add-on accessories if needed.