Siemens 3VA1225-6GF42-0DH0 — 250 A SENTRON MCCB with TM240 Release
The Siemens 3VA1225-6GF42-0DH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current at 40 °C, with a 4-pole configuration and a TM240 thermal-magnetic overcurrent release. Its interrupting capacity reaches 220 kA at 240 V and 154 kA at 415 V, which means it can safely clear high-fault currents in low-voltage distribution without cascading upstream — a key spec for main or tie-breaker positions where available fault current exceeds 100 kA. For line protection duty, this breaker does not include a voltage trigger, communication module, or phase-failure detection — it is a straightforward overcurrent-only device with an undervoltage release (UVR) fitted as standard. The auxiliary contact block is a 2-auxiliary-switch plus 1-trip-alarm-switch HQ variant (order code 3VA9608-0BB25 for the integrated auxiliary trip). The N-conductor protection is rated at 100 %, so the neutral pole is fully rated for the same current as the phase poles — important for 4-wire distribution where the neutral carries load current.
Above 50 °C the continuous current must be derated per the datasheet curve: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C.
Dimensions are 158 mm height, 140 mm width, and 70 mm depth. The 70 mm depth means the breaker protrudes less than 3 inches from the mounting surface — relevant when the panel door clearance is tight or when busbar connections are made on the rear.
With a rated insulation voltage of 800 V and interrupting capacities of 36 kA at 440 V and 17 kA at 690 V, this breaker can be applied in 400 V and 690 V systems, though the interrupting rating drops significantly at the higher voltage. For DC network applications, Siemens directs users to the 3VA MCCB device manual for switching power values — the standard AC ratings do not apply in DC circuits.