What it is and what it does
The Siemens SENTRON 3VA2025-8HM42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, designed for line protection in distribution panels. Its interrupting capacity hits 440 kA at 240 V — that means it can clear a bolted fault up to that level without the arc flashing over to adjacent gear, which is the difference between a localized trip and a panel rebuild.
Key ratings and what they mean for fit
The 25 A continuous rating is the load it carries indefinitely at 40 °C ambient; the spec table shows it holds that same 25 A all the way up to 70 °C (–), so no derating needed in a warm enclosure. The adjustable thermal-magnetic trip range is 38 A minimum to 300 A maximum — that's the short-circuit and overload pickup window, not the continuous rating. Interrupting capacity drops with system voltage: 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V (–). If your fault current at the panel is above those numbers at your line voltage, this breaker isn't the right call. Ground-fault monitoring is built in via summation current formation on L + N conductor — that's a residual-current detection method that sums phase and neutral currents; if they don't cancel, it trips. No undervoltage release and no communication function, so this is a straight thermal-magnetic breaker with ground-fault, not a smart or remote-trip unit.
Where it goes in the panel
Dimensions are 140 mm wide, 181 mm high, 86 mm deep — standard MCCB footprint for a 4-pole 25 A frame. Rated insulation voltage is 800 V.