Switch Disconnector for Load-Break Isolation
The Siemens SENTRON 3VA1225-1AA32-0BH0 is a 3-pole switch disconnector in an MCCB (Molded Case Circuit Breaker) physical design, rated at 250 A continuous current across ambient temperatures up to 50 °C, with a slight derating curve above that: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. This unit is a pure switch disconnector — it provides no overload or short-circuit protection. Its job is safe load-break isolation under load, with a mechanical service life of 15 000 operating cycles typical. The main circuit connects via busbar connection at front terminals.
Above 50 °C, the thermal curve is linear — losing roughly 7 A per 5 °C step — which matters if the disconnector sits near heat sources like transformers or drives. Maximum power loss is 57 W, which should be factored into panel thermal calculations if multiple units are ganged.
No official successor has been issued — this is the active version. For BOM freeze or PCN watch, the SENTRON 3VA platform is Siemens' current MCCB family, so no near-term phase-out is signaled.
Integration Notes
Dimensions: 105 mm wide, 158 mm high, 70 mm deep. Front terminals accept busbar connections for the main circuit; the auxiliary contact block (2 CO + 1 trip alarm) is integrated. The undervoltage release (UVR) is a separate coil that drops the switch when control voltage falls below dropout threshold. It has no leading contact, so the UVR and main contacts open simultaneously — no early-break auxiliary. Verify the 24 V DC supply polarity and free-wheel diode for the UVR coil. Optional motor drive is available as a field-installable extension, enabling remote switching. The trip indicator provides local mechanical flag for open/closed status.