What it is and what it does
The Siemens SENTRON 3VA1225-4EF42-0HA0 is a 4-pole molded case circuit breaker (MCCB) rated 250 A continuous, designed for line protection in distribution panels. It carries a TM240 thermal-magnetic release — the thermal element handles overloads, the magnetic element handles short-circuits — and is fitted with a shunt trip (STL) auxiliary release for remote tripping. Rated insulation voltage is 800 V, and the breaker's interrupting capacity depends on the line voltage: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. That means it can safely clear a fault up to those levels without upstream damage — a key spec for high-fault panels.
Current derating and thermal management
The 250 A rating holds from 40 °C through 50 °C, then steps down: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If the panel ambient runs hot, the breaker's continuous current must be derated accordingly — the full 250 A is only available up to 50 °C. Maximum power loss is 57 W, which matters for enclosure heat calculations.
Panel fit and mounting
Footprint: 140 mm wide, 158 mm high, 70 mm deep. Four poles in a single molded case. No undervoltage release, no ground-fault monitoring, no communication function — this is a straightforward line-protection breaker with a shunt trip for remote disconnect. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.