The Siemens SENTRON 3VM1112-3EE46-0AA2 is a 4-pole molded case circuit breaker (MCCB) rated 125 A continuous, designed for line protection in distribution panels. It carries a TM220 thermal-magnetic overcurrent release — that's a fixed thermal trip with an adjustable magnetic pickup, so you set the short-circuit threshold to coordinate with downstream devices without swapping the breaker body. Interrupting capacity hits 76 kA at 240 V AC, 53 kA at 415 V, 32 kA at 440 V, and 12 kA at 500 V, giving you selectivity headroom across common industrial voltages.
Thermal derating and real-world ampacity
The 125 A rating holds at ambient temperatures up to 50 °C. Above that, the breaker derates linearly: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If your panel runs hot — say, a sealed enclosure near a furnace line or a crowded cabinet with multiple heat sources — you need to size up one frame or accept the reduced continuous current. The 23 W maximum power loss at rated load is manageable but contributes to internal cabinet heating; factor it into your thermal budget.
Mounting and panel fit
This MCCB measures 101.6 mm wide, 130 mm tall, and 70 mm deep. It's a standard panel-mount footprint — no DIN-rail clip on this frame, so you bolt it directly to the mounting plate or into a distribution block. The IP40 front protection means it's splash-safe in the panel but not rated for washdown; keep it behind a sealed enclosure door in wet environments.