The Siemens 3VA1225-5EF42-0AH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current in a 4-pole configuration. It carries a TM240 thermal-magnetic release — the thermal element handles overloads, the magnetic element clears short-circuits — and is designated for line protection, meaning it guards the feeder cable or bus, not a specific load device.
Breaking capacity and selectivity
This MCCB delivers 187 kA breaking capacity at 240 V, 121 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. Those are the Icu (ultimate short-circuit breaking capacity) figures — the breaker can safely interrupt a fault once at those levels. For a 250 A frame, 187 kA at 240 V is high-end; it gives the panel designer headroom for high-fault installations like transformer secondaries or large motor control centers where the available fault current can exceed 100 kA. The 4-pole design (three phases plus neutral switched) is standard for TN-S or TT systems where the neutral needs disconnection.
Thermal derating and operating range
Rated continuous current holds at 250 A from 40 °C through 50 °C ambient. At 55 °C it derates to 243.3 A, at 60 °C to 236.5 A, at 65 °C to 229 A, and at 70 °C to 223 A. That means in a warm panel — say 50 °C internal — you still get full 250 A; above that, the thermal element trips earlier to protect the breaker internals. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The IP40 front protection is typical for panel-mounted breakers — dust-protected but not sealed against water ingress.
Auxiliary contacts and signaling
Fitted with 2 auxiliary switches plus 1 trip alarm switch (HQ designation). The trip alarm signals a fault trip separately from manual on/off status — useful for remote monitoring or PLC input. No undervoltage release, no shunt trip, no communication module on this variant; it's a straightforward thermal-magnetic MCCB with basic auxiliary signaling.