What this part is — and isn't
The Siemens 3VA1225-1AA42-0BA0 is a SENTRON switch disconnector in an MCCB-style frame, rated for a continuous current Iu of 250 A across 4 poles. It is not a circuit breaker — there is no overload or short-circuit trip mechanism built in.
Undervoltage release and control wiring
This unit ships with an undervoltage release (UVR) designed for 24 V DC control. When control voltage drops below the dropout threshold, the release trips the disconnect open — standard practice for emergency-stop chains or undervoltage protection schemes where a loss of control power must isolate the load. The UVR does not have a leading contact, so sequence timing for downstream contactors needs to be handled externally. The disconnect also accepts an optional motor drive for remote operation, though no auxiliary contacts are included on this variant.
Panel fit and wiring
The 3VA1225-1AA42-0BA0 occupies a 140 mm wide, 158 mm tall, 70 mm deep footprint. Main circuit connections are busbar-type front terminals.