What this MCCB is and what it does
The Siemens SENTRON 3VA2125-6KP42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, with an ETU850 electronic trip unit that allows the overload and short-circuit pickup to be adjusted across a 38 A to 300 A range. That adjustment range means a single frame size covers multiple load ratings — useful when a panel design is still being finalized or when the same enclosure needs to accommodate different motor or feeder currents without swapping the breaker body.
Short-circuit withstanding and where it matters
The interrupting ratings vary sharply with system voltage: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 3.7 kA at 690 V. The steep drop at 690 V means this breaker is not a good fit for 690 V distribution — the 3.7 kA SCCR is barely above a typical fault level for a small transformer. At 415 V or 480 V, though, the 187 kA rating gives generous headroom for high-fault installations like substation feeders or large motor control centers.
Panel fit and environment
Dimensions: 140 mm wide, 181 mm high, 86 mm deep. The 140 mm width is standard for a 4-pole MCCB frame.
Trip unit and protection functions
The ETU850 is an electronic trip unit with communication capability. It includes an other measurement function. No ground-fault monitoring version is fitted on this variant.