What this MCCB is and where it fits
The Siemens 3VA2325-8HM42-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels and industrial switchgear. It sits in the 3VA2 family — the compact, high-performance frame that replaced the 3VL series. At 250 A continuous rating and 4 poles, this breaker handles three-phase plus neutral loads in a single enclosure, sized for main or large feeder duty.
Rated current and thermal derating — what the flat curve means
Rated continuous current is 250 A, and it holds that rating flat from 40 °C all the way to 70 °C ambient (–). That is unusual — most MCCBs start derating above 40 °C. Here, the breaker delivers full 250 A in a hot panel or outdoor enclosure without needing an upsized frame. The adjustable thermal-magnetic trip unit covers 375 A minimum to 3 000 A maximum short-circuit release, so the same breaker body can be tuned for different feeder sizes by swapping the trip pack.
Short-circuit withstand — the number that decides the bus rating
Short-circuit breaking capacity is given per voltage level, and this is the spec that determines whether the breaker clears a fault without upstream coordination failure. At 240 V it interrupts 440 kA; at 415 V and 440 V, 330 kA; at 500 V, 220 kA; and at 690 V, 52.5 kA. The 690 V figure is the one to check for 600 V class industrial systems — 52.5 kA is high enough for most secondary distribution but not for a main service entrance with a utility transformer rated above 2 MVA. Rated insulation voltage is 800 V, so the breaker is electrically rated for 690 V networks with margin.
Ground-fault and panel fit
This version includes ground-fault monitoring via summation current formation on L + N conductor — it sums the phase and neutral currents and trips if the vector sum exceeds the threshold. That makes it suitable for solidly-grounded or resistance-grounded systems where ground-fault protection is required by code. Panel dimensions are 248 mm high, 184 mm wide, 110 mm deep — standard 4-pole MCCB footprint for a 250 A frame. Maximum power loss is 37.5 W, which matters for enclosure thermal calculations when grouping multiple breakers.