The Siemens SENTRON 3VA2125-8HN36-0AA0 is a 3-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 duty — the kind of fixed, non-communicating breaker you spec into a distribution panel where you need reliable overcurrent protection without extra monitoring layers.
Key ratings and what they mean for fit
The 25 A continuous rating holds flat across the full operating temperature range from -25 °C to 70 °C — no derating curve to chase in a warm enclosure. Insulation voltage is rated at 800 V, so it's comfortable in 480 V and 600 V class systems with headroom to spare. Breaking capacity is the headline number that decides whether this breaker clears a fault or welds shut. At 240 V it's rated for 440 kA; at 415 V and 440 V it holds at 330 kA; at 500 V it's 220 kA; and at 690 V it drops to 52.5 kA. For most North American 480Y/277 V panels the 330 kA figure applies — that's well above typical available fault current in commercial and light industrial distribution, so it gives you selectivity headroom without needing a current-limiting upstream device. The ETU350 electronic trip unit is a fixed-function, non-adjustable release — no dials for long-time, short-time, or instantaneous pickup. It's a straight thermal-magnetic replacement in electronic form, meaning it's a drop-in choice for a BOM line that just needs a coordinated 25 A breaker without commissioning steps.
Dimensions and panel fit
At 181 mm high, 105 mm wide, and 86 mm deep, this 3VA frame fits standard MCCB mounting footprints in Siemens SENTRON distribution panels and most third-party enclosures with a DIN-rail adapter or direct screw-mount plate. The IP40 front protection means it's fine in a clean indoor panel but not in washdown zones or outdoor cabinets without a higher-rated enclosure over it.
Lifecycle and sourcing reality
Power loss is listed at 0.5 W maximum — negligible for panel thermal budgeting, but worth noting if you're packing a high-density enclosure and tracking every watt.