What this MCCB carries — and where it fits
The Siemens 3VA1125-5EF36-0CC0 is a SENTRON molded case circuit breaker (MCCB) built for line protection in three-phase distribution panels. It carries a 25 A continuous rating at 40 °C, and the thermal derating curve holds that same 25 A through 50 °C, then steps down to 24 A at 55–60 °C and 23 A at 65–70 °C — so in a warm enclosure you lose only a couple of amps. The 3-pole design breaks all phases simultaneously, and the 187 kA interrupting rating at 240 V AC gives serious fault-clearing headroom for high-available-fault panels. At 415 V it still handles 121 kA, at 440 V it's 75.6 kA, and at 500 V or 690 V it's 17 kA — that's a lot of SCCR margin for most industrial distribution boards. This variant ships with an undervoltage release (UVR) and two auxiliary switches HQ built in — the UVR trips the breaker when control voltage drops below a threshold, which is standard for emergency-stop or undervoltage protection schemes. The auxiliary switches give status feedback to a PLC or indication lamp without extra wiring. The rated insulation voltage is 800 V, so it's comfortable on 480/277 V or 600 V systems with margin. Mounting dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a standard MCCB footprint that drops into most DIN-rail or panel-mount enclosures without rework. Power loss is 11 W maximum, which is modest for a 25 A frame; factor that into enclosure thermal calculations if you're packing several breakers side by side.
What the breaking capacity numbers mean for coordination
The 187 kA at 240 V is the maximum short-circuit current this breaker can safely interrupt at that voltage — useful for panels fed from large transformers where the prospective fault current is high. At 415 V (common in European industrial systems) the 121 kA still covers most distribution boards. The drop to 17 kA at 500 V and 690 V means on higher-voltage systems you need to verify the available fault current doesn't exceed that limit. For a 25 A frame, these are high-end numbers; the 3VA series is designed for selective coordination with downstream MCBs.