What this MCCB carries and what it means for your panel
The Siemens SENTRON 3VA2125-6KQ42-0DK0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, with a full-scale value of 25 A and a maximum current of 40 A. Its interrupting capacity hits 242 kA at 240 V and 187 kA at 415 V — numbers that tell you it's built for high-fault installations where a standard MCB would weld shut. At 690 V the rating drops to 3.7 kA, so if your line runs at that voltage, verify the available fault current stays under that ceiling. The 25 A rating holds flat across the entire ambient range from 40 °C to 70 °C — no derating curve to chase. That simplifies panel layout in warm enclosures or near heat sources. It ships with an undervoltage release (UVR) and a complement of auxiliary switches: one auxiliary, one trip alarm, and one electrical alarm switch HQ. The UVR means the breaker drops on loss of control voltage — useful for emergency-stop circuits or coordinated shutdown sequences.
Integration and mounting
The 3VA2125-6KQ42-0DK0 measures 86 mm deep by 140 mm wide by 181 mm high — a standard SENTRON 3VA footprint that drops into existing panel cutouts and DIN-rail mounting schemes. The 4-pole body occupies the same width as the 3-pole variant plus one pole space; plan your busbar and gland-plate layout accordingly.
Selectivity and coordination note
With a minimum trip setting of 1.5 A and a maximum of 40 A, this breaker covers a wide branch range. The 242 kA SCCR at 240 V gives headroom for transformer-fed panels where upstream devices are already coordinated. The communication function (listed as present) allows integration into a monitoring system — useful for remote trip indication or load shedding.