What this MCCB brings to the panel
The Siemens 3VA1112-3ED26-0AA0 is a SENTRON molded case circuit breaker sized for 125 A continuous duty in a 2-pole package. It carries a TM210 thermal-magnetic release — that means the thermal element handles overloads and the magnetic trip handles short circuits, with the instantaneous pickup fixed at 1250 A. At 240 V it interrupts 75.6 kA; at 415 V that drops to 52.5 kA, so the available fault current at the panelboard is what decides the fit. The 70 mm depth and 50.8 mm width let it tuck into a standard MCCB slot without stealing extra DIN rail real estate.
Derating and thermal reality
This breaker holds its full 125 A rating from 40 °C up through 50 °C. At 55 °C it derates to 122 A, at 60 °C to 120 A, and at 70 °C to 114 A. That's a clean thermal curve — no surprise drop at 45 °C. If the panel ambient runs hot, the 125 A nameplate is still good for most of the range. Maximum power loss hits 18.74 W, which matters for heat buildup inside a sealed enclosure.
Panel fit and environment
Front-face protection is IP40 — fine for a clean indoor panel, but not for washdown or outdoor exposure. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C. The 2-pole form factor and 50.8 mm width mean it fits the same footprint as other SENTRON 2-pole MCCBs; no panel rework needed if swapping from a similar unit.
Compliance and documentation
Rated insulation voltage is 500 V. The breaker is designed for line protection (not motor protection or ground-fault). No communication function, no motor drive option, no neutral conductor upgrade. Reference code per IEC 81346-2 is Q. Standard compliance documentation (CE, UL, IEC) is available from the manufacturer for this series.