The Siemens 3VA2125-8KQ42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 25 A continuous current, with a 4-pole configuration and a breaking capacity of 440 kA at 240 V AC. This is a line-protection design with integrated ground-fault monitoring via summation current formation on the L + N conductors, and it includes a communication function for integration into higher-level control or monitoring systems.
Breaking capacity and selectivity
Breaking capacity drops from 440 kA at 240 V to 330 kA at 415 V and 440 V, then to 220 kA at 500 V, and 52.5 kA at 690 V. For a site engineer planning selectivity, the 440 kA at 240 V means this breaker can sit upstream of downstream devices with lower SCCR ratings, provided the let-through energy is coordinated — the high interrupt rating gives headroom for transformer-secondary or large motor-start applications where fault current is substantial.
Thermal performance and derating
Rated continuous current holds at 25 A across the full ambient temperature range from 40 °C through 70 °C — no derating required up to 70 °C. The minimum adjustable trip setting is 38 A, and the maximum is 300 A, so the breaker can be dialed to protect a range of downstream loads. The 0.5 W maximum power loss is low enough that multiple units can be ganged in a panel without forced cooling.
Mounting and integration
Dimensions are 86 mm deep, 140 mm wide, 181 mm tall — a 4-pole MCCB that fits a standard panel-mount cutout. The communication function and ground-fault monitoring (summation current L+N) mean it can report trip events and leakage to a PLC or BMS without an add-on module. No undervoltage release or voltage-trigger function is built in, so external trip coils would be needed for those schemes.