What this MCCB carries and where it fits
The Siemens 3VA1112-5EF36-0CC0 is a SENTRON molded case circuit breaker rated for 125 A continuous current (Iu) across three poles, with a TM240 thermal-magnetic overcurrent release. That TM designation means the thermal element handles overloads and the magnetic element handles short-circuits — no electronic trip unit, so no auxiliary power needed for the trip curve. Breaking capacity runs from 187 kA at 240 V down to 17 kA at 690 V, which gives selectivity headroom for most distribution panels without cascading upstream. The 800 V rated insulation voltage (Ui) covers 480/600 VAC systems with margin. Panel builders will note the 70 mm depth and 76.2 mm width — standard 3-pole MCCB footprint for DIN-rail or screw-mount chassis integration.
Thermal derating and ambient limits
The 125 A rating holds flat from 40 °C through 50 °C. Above that it derates linearly: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, 112.5 A at 70 °C. If the panel ambient runs hot — say a packed enclosure near a furnace line — that 112.5 A floor at 70 °C still leaves headroom for a 100 A continuous load. Operating range is -25 °C to 70 °C; storage from -40 °C to 80 °C. The IP40 front protection keeps dust out of the mechanism but won't survive washdown — keep it inside the enclosure.
Auxiliary and undervoltage release
This variant ships with two factory-fitted HQ auxiliary switches (3VA9608-0BB24) and an undervoltage release (UVR). The UVR drops the breaker when control voltage falls below a threshold — standard for emergency-stop chains or undervoltage protection on motor feeders. The two auxiliary contacts give status feedback to a PLC or indication lamp without adding a separate contact block. No communication module, no ground-fault monitoring, no voltage-trip trigger on this build.