What this MCCB is and what it does
The Siemens 3VA2225-8HL42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current, with a 4-pole configuration and an ETU320 electronic trip unit. It is designed for line protection in distribution panels and industrial switchboards, where it provides adjustable overload and short-circuit protection for cables and busbars. The ETU320 trip unit allows the long-time pickup to be set between 375 A and 2500 A, covering a wide range of feeder and main breaker applications. The breaker's rated insulation voltage is 800 V, and it dissipates up to 48 W at full load.
Breaking capacity — what the ratings mean for fit
This MCCB carries a 440 kA interrupting rating at 240 V AC, dropping to 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. These are the maximum fault currents the breaker can safely clear at each voltage level — critical for verifying coordination with upstream transformers and downstream equipment. The 440 kA at 240 V is typical for high-fault-capacity service-entrance or large-feeder positions in North American 277/480 V panels where the line-to-neutral fault can exceed 200 kA.
Thermal derating and operating limits
The breaker holds its full 250 A rating up to 50 °C ambient. Above that, it derates linearly: 241 A at 55 °C, 232 A at 60 °C, 222 A at 65 °C, and 213 A at 70 °C. The operating temperature range is -25 °C to +70 °C, with storage from -40 °C to +80 °C. The front face carries an IP40 protection rating — suitable for dry indoor panels but not washdown environments.
Physical fit and panel integration
The breaker measures 181 mm high, 140 mm wide, and 86 mm deep. It mounts on a DIN rail or directly to a panel backplate via the SENTRON 3VA2 mounting accessories. The 4-pole width (140 mm) is the same as other 4-pole 3VA2 frames, so a panel drilled for a 3VA2 250 A frame accepts this unit without rework.