What it is and what it does
The Siemens 3VA1225-6GF42-0CA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It is a 4-pole unit rated 250 A continuous, fitted with a TM240 thermal-magnetic overcurrent release and an integrated undervoltage release (UVR). The interrupting capacity reaches 220 kA at 240 V and 154 kA at 415 V, so it handles high-fault scenarios common in industrial mains or large sub-distribution boards.
Ratings and what they mean for fit
The 250 A continuous rating holds at ambient temperatures up to 50 °C without derating; above that it drops to 243 A at 55 °C and 223 A at 70 °C. If your panel runs hot, the effective current is lower than the nameplate. The TM240 release is a thermal-magnetic type — thermal for overload, magnetic for short-circuit — so it is a standard choice for cable and busbar protection in a main or feeder breaker role. Interrupting capacity varies sharply with system voltage: 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. At 690 V the 17 kA figure is the limiting case; verify your available fault current against that number before specifying this breaker on a 690 V bus. Rated insulation voltage is 800 V, and the maximum power loss is 59.5 W at rated load — relevant for thermal management inside a closed panel.
Panel integration notes
Dimensions are 158 mm high, 140 mm wide, 70 mm deep — a standard SENTRON 3VA footprint that fits most DIN-rail or panel-mount enclosures. The 4-pole body takes up 140 mm of rail width; verify fill factor if retrofitting into an existing distribution board.