What it is and what it does
The Siemens 3VA1225-4EF32-0BC0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It is a 3-pole unit rated at 250 A continuous current at 40 °C ambient, with a rated insulation voltage of 800 V. The breaking capacity is 121 kA at 240 V AC, 75.6 kA at 415 V, and 52.5 kA at 440 V — figures that tell you it can handle high-fault-current scenarios like large transformer secondaries or main feeders in industrial switchgear. At 500 V it still interrupts 17 kA; at 690 V, 11.9 kA. The continuous current holds at 250 A up to 50 °C, then derates to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — a thermal curve you need if the breaker sits in a warm enclosure or next to other heat sources.
Key ratings and what they mean for fit
The 250 A frame size and 3-pole configuration are the primary fit check: this breaker goes into a 3-phase feeder or large motor circuit. The 121 kA interrupting rating at 240 V is the headline number — it means the breaker can safely clear a fault up to that level without rupturing, which is essential for service-entrance or high-capacity distribution where available fault current is high. The undervoltage release (UVR) is built in (design of the auxiliary release: undervoltage release), so the breaker trips if supply voltage drops below a threshold — typical for applications where you need to prevent automatic restart after a power loss. The auxiliary switch configuration is 2 HQ switches, which gives you two form-C contacts for status feedback to a PLC or indication panel.
Where it goes and how it mounts
The 3VA1225-4EF32-0BC0 is a panel-mount MCCB. Dimensions are 105 mm wide, 158 mm high, and 70 mm deep.