What this MCCB delivers
The Siemens SENTRON 3VA1125-3EF32-0KA0 is a 3-pole molded case circuit breaker (MCCB) rated for 25 A continuous current at 40 °C, with a TM240 thermal-magnetic overcurrent release. It carries a 75.6 kA interrupting capacity at 240 V, stepping down to 52.5 kA at 415 V and 32 kA at 440 V — enough to handle high-fault utility feeds or transformer secondaries in a distribution panel. The 800 V rated insulation voltage (Ui) means it can sit on 690 V line-to-line systems without derating the insulation path. This is a line-protection version — no ground-fault monitoring, no undervoltage release, no communication module. The only auxiliary is a shunt trip (STL) release, ordered separately as 3VA9688-0BL33. For a panel builder, that means the breaker is a clean overcurrent-only device; any remote trip or status feedback requires adding that shunt trip and wiring it into a safety or PLC circuit.
Thermal derating and panel fit
The 25 A rating holds flat from 40 °C to 50 °C. Above that, it derates: 24 A at 55 °C, 23.5 A at 60 °C, 23 A at 65 °C, and 22.5 A at 70 °C. If the panel ambient runs above 50 °C, size the load circuit for the lower figure — the TM240 release will track the bimetallic curve, not the nameplate. The breaker measures 70 mm deep by 76.2 mm wide by 130 mm high, with IP40 protection on the front face. That width matches the standard 3VA1110/1112 footprint, so a panel laid out for those siblings accepts this unit without re-drilling the mounting plate.