Siemens 3VA1225-6EF42-0CH0 — 250 A SENTRON MCCB for Line Protection
The Siemens 3VA1225-6EF42-0CH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A at 40 °C, with a 4-pole configuration and a breaking capacity of 220 kA at 240 V. It is designed for line protection and comes with an integrated undervoltage release. The 220 kA interrupting rating at 240 V means this breaker can safely clear very high fault currents typical of large transformer-fed or utility-tied distribution panels — it's not a branch-circuit device. At 415 V the rating drops to 154 kA, and at 690 V to 17 kA, so selectivity studies need to account for the voltage-dependent curve. Rated insulation voltage is 800 V, which covers most 480/277 V and 600 V industrial systems with margin. The 59.5 W maximum power loss at rated load matters for panel thermal calculations — especially in a densely populated enclosure.
Current Rating and Thermal Derating
The 250 A rating holds steady from 40 °C through 50 °C ambient. At 55 °C it derates to 243 A, at 60 °C to 237 A, at 65 °C to 230 A, and at 70 °C to 223 A. If the panel ambient runs above 50 °C, size the breaker for the derated value, not the nameplate.
Dimensions and Panel Fit
The breaker measures 158 mm high, 140 mm wide, and 70 mm deep. The 140 mm width is the standard 4-pole MCCB footprint for this class — verify the mounting base and busbar spacing in the existing panel before ordering.
Auxiliary and Release Configuration
This variant ships with 2 auxiliary switches plus 1 trip alarm switch (HQ type), and an undervoltage release (UVR) fitted. The UVR automatically trips the breaker when control voltage drops below a threshold — common for emergency-stop chains or undervoltage protection schemes. No ground-fault monitoring or communication function is included on this order code.