What it is and what it does
The Siemens SENTRON 3VA2125-5MN32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, designed specifically for motor protection. It includes phase failure detection and adjustable trip classes 10A, 10E, and 20E, letting you match the thermal curve to the motor's starting profile. The interrupting capacity hits 187 kA at 240 V, 121 kA at 415 V, and still holds 75.6 kA at 500 V — enough for high-fault industrial panels without cascading upstream.
Panel fit and integration
Dimensions are 105 mm wide, 181 mm high, and 86 mm deep — a standard MCCB footprint for DIN-rail or panel-mount enclosures. The 3-pole design with no undervoltage release or communication module keeps wiring simple: line in, load out, and a separate control circuit for the trip coil if needed. Ambient temperature range is -25 °C to 70 °C operating, so it handles warm cabinet interiors without derating the 25 A rating across the full span.
What the ratings mean for your decision
The 25 A rating holds steady from 40 °C to 70 °C — no derating curve to calculate for typical panel temperatures. The adjustable trip class (10A, 10E, 20E) lets you set the overload delay: 10A for standard motor start, 10E for longer acceleration (e.g., high-inertia loads), 20E for extended start times. Phase failure detection trips the breaker if one phase drops out, protecting the motor from single-phasing. Maximum power loss is only 0.6 W, negligible for thermal budgeting in a crowded enclosure.