The Siemens SENTRON 3VA2125-7HN42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, built around the ETU350 electronic trip unit. It's designed for line protection in distribution panels, with an interrupting capacity that reaches 330 kA at 240 V and stays above 240 kA through 440 V — that's the kind of headroom you want when coordinating with downstream breakers in a high-fault industrial service.
Ratings and what they mean for fit
The 25 A continuous rating holds flat across the entire operating temperature range from 40 °C to 70 °C — no derating curve to worry about in a warm panel. The 800 V rated insulation voltage means it's comfortable on 480 V or 600 V class systems with margin. The ETU350 trip unit gives you adjustable overload and short-circuit protection; it's an electronic trip, so you get better accuracy and selectivity than a thermal-magnetic on the same frame. Interrupting capacity drops to 3.7 kA at 690 V — that's still adequate for most 690 V motor control centers, but if your fault current at that voltage is higher, you'll need a current-limiting upstream device or a higher-rated frame. The 4-pole configuration suits three-phase systems with a switched neutral or dual-supply applications.
Physical fit and panel integration
The breaker measures 140 mm wide, 181 mm tall, and 86 mm deep — that's a standard SENTRON 3VA2 frame footprint. It mounts on a DIN rail or can be screw-fixed to a backplate. The IP40 protection on the front means it's splash-proof from the front but not sealed; keep it inside a rated enclosure in wet environments.