The Siemens 3VA1125-4EF32-0KA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 25 A rated current at 40 °C, confirmed across the ambient range up to 70 °C where it derates to 23 A. The 3-pole frame uses a TM240 thermal-magnetic overcurrent release, so the thermal element handles overloads and the magnetic element clears short-circuits — no electronic adjustment, just a fixed curve suited to feeder and branch-circuit protection. Breaking capacity is the headline number here: 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. Those are the maximum fault currents this MCCB can safely interrupt at each voltage level — critical when the available fault current at the panel is known. The rated insulation voltage is 800 V, so the internal clearances are sized for 690 V systems without derating the dielectric. This variant includes a shunt trip (STL) auxiliary release — a separate control voltage triggers the breaker open remotely, which is standard for emergency-stop circuits or interlocking schemes. The undervoltage release is not fitted on this order code, so if UV protection is required, that is a different variant.
Sourcing & Lifecycle
Lifecycle stage is current; Siemens still manufactures this order code as an active catalog item.
Panel Fit & Integration
Dimensions: 130 mm height, 76.2 mm width, 70 mm depth. Mounts on DIN rail or backplate. Maximum power loss is 8.5 W, which is moderate for a 25 A MCCB. In a sealed enclosure with multiple breakers, that heat adds up — factor it into the thermal budget if the panel is densely populated. Operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C.