The Siemens SENTRON 3VA2125-5HN42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated at 25 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed for warm panel environments. It carries an interrupting rating of 187 kA at 240 V and 121 kA at 415 V, which means it can safely clear high-fault currents in low-voltage distribution without cascading upstream. The ETU350 electronic trip unit provides adjustable N-conductor protection (OFF or 100%) and line protection for the main feeder.
Key ratings and what they mean for fit
The 25 A rating is stable from 40 °C to 70 °C — you don't lose capacity as the panel warms up, which is a practical advantage for a densely packed enclosure. The interrupting rating of 187 kA at 240 V and 121 kA at 415 V covers most industrial service-entrance and feeder applications; at 690 V it drops to 3.7 kA, so it's not suited for high-voltage motor circuits at that level. The ETU350 release is an electronic trip unit with adjustable N-protection, giving you flexibility to set the neutral pole to 100% or OFF depending on the system grounding scheme.
Panel integration
Dimensions are 140 mm wide, 181 mm high, and 86 mm deep — fits standard MCCB mounting footprints. The front face carries an IP40 rating, so it's protected against tools and solid objects larger than 1 mm; no washdown rating, so keep it inside the enclosure. No undervoltage release or communication function on this variant — it's a straight line-protection breaker with no auxiliaries.