What it is and what it does
The Siemens 3VA1025-3ED32-0HC0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It's a 3-pole unit rated at 25 A continuous current at ambient temperatures up to 50 °C, with a slight derating to 23 A at 70 °C. The rated insulation voltage is 800 V, and the interrupting capacity hits 75.6 kA at 240 V, dropping to 7.5 kA at 690 V — so it's built for high-fault scenarios on the low-voltage side of a transformer, not for 690 V motor circuits where the fault current is lower anyway.
Physical fit and panel integration
The breaker measures 130 mm tall, 76.2 mm wide, and 70 mm deep — a compact 3-pole footprint that fits standard SENTRON mounting bases in a distribution board. The 70 mm depth means it'll clear most shallow enclosures, but check the gland plate clearance if you're back-paneling with cable ducts. Max power loss is 8.5 W, so ventilation in a sealed cabinet is worth a thought if you're stacking several of these.
What the ratings mean for your BOM line
The 25 A rating at 40-50 °C is the continuous current you can count on without derating — that's the number for sizing feeder cables and upstream protection. Above 55 °C, the breaker derates linearly to 23 A at 70 °C, so if your panel ambient runs hot, size up one frame. The 75.6 kA interrupting rating at 240 V is the headline number for high-fault locations like service entrances; at 415 V it's still 52.5 kA, which covers most industrial distribution. The 800 V rated insulation voltage means it's suitable for 480/277 V and 600 V systems with margin.