That AC-3 rating means it's sized for starting and stopping squirrel-cage motors under load, not just resistive heating. The operating voltage range is 400 to 500 V, and the control supply is 24 V DC, with a permissible range of 20.4 to 28.8 V.
Where it goes and how it connects
This is a field-mount unit, not a DIN-rail panel device. The main energy infeed and load-side outgoing feeder use sockets per ISO 23570, and the supply-voltage line-side connection is a hybrid plug. Communication uses a hybrid plug/socket pair for PROFIBUS DP. Two digital inputs are provided via M12 sockets, parameterizable for functions like start, stop, or direction selection. There are no digital outputs. The brake control for 400 V AC is not supported — if you need a DC brake, that's handled separately.