The Siemens 3VA1125-5EF36-0CH0 is a SENTRON molded case circuit breaker (MCCB) rated for 25 A continuous current (Iu) in a 3-pole configuration, designed for line protection. Its TM240 thermal-magnetic overcurrent release provides fixed protection against overload and short circuits. The part carries a 187 kA breaking capacity at 240 V, tapering to 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V — these are the interrupting ratings that govern its placement in the fault-current hierarchy of a panel.
Breaking capacity and selectivity
At 240 V the 187 kA rating places this MCCB well above the typical utility fault-current range for North American 240/120 V split-phase services. At 415 V the 121 kA figure covers most industrial secondary-side transformer faults. The 690 V rating of 17 kA is the limiting case — if your panel's available fault current at 690 V exceeds that, you need a current-limiting upstream device or a higher-rated frame. The 800 V rated insulation voltage (Ui) confirms the internal clearances support 690 V line-to-line without derating.
Thermal derating and panel integration
The 25 A rating holds flat from 40 °C to 50 °C ambient. Above that the thermal-magnetic trip begins to shift: 24 A at 55 °C, 23.5 A at 60 °C, 23 A at 65 °C, and 22.5 A at 70 °C. If the breaker is mounted in a sealed enclosure or next to heat-generating gear, size the load current against the derated value at the actual cabinet ambient. The front face carries IP40 protection — fine for a clean panel; not rated for washdown or outdoor exposure. Dimensions are 70 mm deep, 76.2 mm wide, 130 mm high, fitting standard SENTRON 3VA panel footprints.
Auxiliary contacts and undervoltage release
Factory-fitted with 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), and an undervoltage release (UVR). The UVR is specified as design type 3VA9608-0BB24. The UVR will open the breaker when control voltage drops below the dropout threshold — useful for emergency-stop circuits or undervoltage protection on motor feeders. The auxiliary contacts can be wired into a PLC input for remote status of the breaker position.