What this MCCB is and what it does
The Siemens 3VA2325-7MN32-0CB0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) in the motor protection version, rated for a continuous current Iu of 250 A across the full ambient range from 40 °C to 70 °C with no derating required. Its three poles and 800 V rated insulation voltage suit it for 400 V and 480 V distribution panels feeding motor loads, pumps, or compressors where phase-failure detection and undervoltage release are specified. The interrupting capacity reaches 330 kA at 240 V and 242 kA at 415 V, dropping to 7.5 kA at 690 V — the high short-circuit ratings at common low-voltage levels mean this breaker can be applied upstream in high-fault-capacity installations without cascading coordination issues.
Key ratings and what they mean for fit
The 250 A continuous rating holds flat from 40 °C to 70 °C — no thermal derating curve to calculate for warm enclosures, which simplifies panel sizing. The 330 kA interrupting rating at 240 V is the headline number, but the more relevant figure for a 400 V three-phase system is 242 kA at 415 V, still well above typical industrial service-entrance fault levels. At 690 V the capacity drops to 7.5 kA, so this breaker is not intended for 690 V motor circuits unless the available fault current is verified below that threshold. The 20 000-cycle latching endurance reflects a robust mechanism for frequent switching applications, though it is not a full-load switching rating — that is the contactor's job.
Integration and auxiliary features
This MCCB ships with two HP auxiliary switches and an integrated undervoltage release — the UVR trips the breaker when control voltage drops, preventing automatic reclosure after a power loss. Phase failure detection is built in, so no external phase-loss relay is needed for motor protection schemes. The 138 mm width and 248 mm height fit standard SENTRON 3VA2 panel cutouts; the 110 mm depth leaves clearance for rear-connected busbars. Maximum power loss is 38 W, which should be factored into enclosure thermal calculations when multiple breakers are ganged.