125 A MCCB with TM240 release — what the ratings mean for your panel
The Siemens 3VA1112-4EF32-0AH0 is a 3-pole SENTRON molded case circuit breaker rated for 125 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. That 125 A holds flat from 40 °C through 50 °C ambient, then derates to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C — so in a warm enclosure you lose about 10 % of headroom at the top end. The TM240 designation means the thermal element is fixed at 240 A frame rating with an adjustable magnetic trip; the time delay tr max. is 1 s, which governs short-time withstand for selective coordination downstream. Breaking capacity is what decides whether this breaker clears a fault without upstream devices needing to trip. At 240 V it interrupts 121 kA; at 415 V, 75.6 kA; at 440 V, 52.5 kA; and at 690 V, 11.9 kA. For a 480 V panel feed, the 52.5 kA at 440 V is the closest published figure — that is well above typical utility fault levels for a distribution board, so it gives solid SCCR headroom for downstream branch protection.
Panel fit and auxiliary wiring
Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a standard 3-pole MCCB footprint that drops into a SENTRON distribution panel or a DIN-rail adapter. The auxiliary contact block is factory-fitted as 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), so you get both a signal contact for the closed position and a separate alarm contact that changes state only on a trip event. That saves a wiring step versus adding a separate alarm module later. Front IP40 protection keeps dust out of the enclosure cutout.