The Siemens 3VA1125-5EF46-0AA0 is a SENTRON 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current at 40 °C, using a TM240 thermal-magnetic overcurrent release. It's built for line protection in distribution panels where you need high interrupting capacity across multiple voltage levels — 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and still 17 kA at 500 V and 690 V. That kind of curve tells you this breaker is designed for strong fault current discrimination downstream of a large transformer or generator.
Ratings and what they mean for fit
The 25 A rating holds flat from 40 °C through 50 °C, then derates to 24 A at 55–60 °C and 23 A at 65–70 °C. If your panel ambient runs hot — say near a transformer or in a non-conditioned enclosure — that derating curve is what governs the actual load you can protect. The TM240 trip unit is thermal-magnetic: the thermal element handles overloads (slow response, I²t curve), the magnetic element handles short-circuit instantaneous trip. No ground-fault monitoring on this variant, and no N-conductor protection built in. Rated insulation voltage Ui is 800 V, and max operational voltage hits 600 V DC. Power loss at rated current is 8.5 W — modest for a 4-pole frame, but worth accounting for in a densely packed panel with multiple breakers side by side. IP40 on the front means it's protected against tools and wires >1 mm, but not against moisture ingress; keep it inside a rated enclosure.
Panel fit and integration
Dimensions are 70 mm deep × 101.6 mm wide × 130 mm high. The 4-pole width (101.6 mm) is standard for a 4-pole MCCB in this class — it occupies four 25 mm module positions on a DIN rail or mounting plate. Verify the busbar system and phase spacing in your existing panel; if the previous breaker was a 3-pole unit, you'll need the fourth pole's clearance and connection.