Breaking capacity and selectivity
The Siemens SENTRON 3VA1225-4EF32-0DH0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection. Its 250 A continuous current (Iu) is thermally rated up to 50 °C without derating; at 55 °C it holds 243.3 A, and at 70 °C it still carries 223 A — so in a warm panel you lose less than 11 % of capacity at the top end. The TM240 thermal-magnetic release gives fixed thermal and magnetic trip settings, no field adjustment. Breaking capacity is the headline: 121 kA at 240 V AC, 75.6 kA at 415 V, 25 kA at 440 V, and 11.9 kA at 690 V. That 121 kA at 240 V means it can sit downstream of a large transformer or a high-fault bus without needing a current-limiting fuse ahead of it — the breaker clears the fault itself. At 415 V the 75.6 kA still covers most industrial distribution panels. Selectivity studies for a 250 A frame at these SCCR levels are straightforward; the 3VA series has published coordination tables.
Auxiliary and undervoltage release configuration
This variant ships with an undervoltage release (UVR) as the auxiliary release — part number 3VA9608-0BB25 for the integrated trip unit — plus 2 auxiliary switches and 1 trip alarm switch (HQ). The UVR means the breaker trips when control voltage drops below a threshold, standard for emergency-stop chains or undervoltage protection schemes. The auxiliary contacts report status back to a PLC or panel lamp; the trip alarm switch signals a fault trip separately from a manual open.
Panel integration
Dimensions: 105 mm wide, 158 mm high, 70 mm deep — fits standard MCCB panel cutouts and DIN-rail adapter plates. IP40 on the front means it is protected against tools and small wires entering the front face, standard for enclosed distribution boards. Storage range from -40 °C to 80 °C; operating range -25 °C to 70 °C. The 70 mm depth leaves room for cable bending behind the breaker in a 200 mm deep enclosure.