What it is and what it does
The SENTRON 3VA1125-5GF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated 25 A continuous, with a TM240 thermal-magnetic release. It's a line-protection device — the core job is clearing faults fast enough to protect downstream cables and equipment without taking out the whole panel. The interrupting ratings climb to 187 kA at 240 V and still hold 121 kA at 415 V, which puts it in the high-fault-current bracket for industrial mains or large sub-distribution boards. Insulation voltage is rated 800 V, so it's comfortable on 480/600 V systems.
What the ratings mean for your panel
The 25 A rating holds across the full 40–50 °C range and only starts to derate at 55 °C (24 A) and 70 °C (23 A) — so in a warm enclosure you still get nearly the full continuous current. The TM240 release is a thermal-magnetic type: the thermal element handles overloads, the magnetic element handles short circuits. No undervoltage release, no ground-fault monitoring, no communication function — this is a straight breaker, not a smart device. The IP40 on the front means it's protected against tools and wires >1 mm, but not against water; keep it inside the panel, not on a washdown wall.
Dimensions and panel fit
The breaker measures 101.6 mm wide by 130 mm tall by 70 mm deep. That 70 mm depth is shallow enough to fit most standard distribution enclosures without hitting the backplate or door. The 4-pole width (101.6 mm) is a standard 4-module footprint for SENTRON MCCBs — it'll drop into the same busbar or mounting plate as other 4-pole 3VA breakers. No trip indicator, no voltage trigger — just the handle position tells you the state.