What this MCCB carries
The Siemens 3VA1125-5EF32-0KH0 is a SENTRON molded case circuit breaker built for line protection — 3-pole, rated 25 A continuous at 40 °C, with a 187 kA interrupting capacity at 240 VAC. That 187 kA figure at 240 V means it can clear a bolted fault on a high-capacity transformer secondary without the arc re-striking; the 121 kA at 415 V and 75.6 kA at 440 V still cover most industrial distribution panels. Rated insulation voltage is 800 V, so it's comfortable in 480 V or 600 V class systems as well. Thermal derating is minimal through 50 °C — still 25 A — then drops only 1 A per 5 °C step to 23 A at 70 °C. That's a flat curve; you don't lose much headroom in a warm enclosure. Power loss maxes at 8.5 W, so heat buildup in a crowded panel is manageable.
Auxiliary and release configuration
This variant ships with a factory-fitted shunt trip (STL) release and a 2+1 auxiliary switch block — two NO/NC auxiliary switches plus a separate trip alarm switch (HQ). That's enough for remote status and alarm feedback without adding a separate module. No undervoltage release, no ground-fault monitoring, no communication function — it's a straightforward line-protection breaker with remote trip capability. The base switch mechanism is the 3VA11255EF320AA0 sub-assembly. Panel footprint is 76.2 mm wide, 130 mm tall, 70 mm deep — standard 3-pole MCCB spacing for DIN-rail or backplate mounting. If you're swapping into an existing panel laid out for a 3VA1110 frame, check the lug centers; the 3VA1125 frame is the same width but slightly deeper, so busbar alignment should hold.