Both can run on a 400 V network; what decides the choice is the connection the motor will use at 400 V and the starting method in the panel. A model rated 230/400 V reaches its rated values on this supply in star (Y), while a model rated 400/690 V does so in delta (Δ). For a direct start this difference is harmless; with star-delta starting it is decisive.

DRG-100L-2 3 kW 3000 rpm aluminium frame DRG three-phase motor – 230/400 V vs 400/690 V motor

What do the two values on the nameplate mean?

The first figure is the line voltage for delta connection and the second is the line voltage for star connection. Each coil of the winding is built for the lower value. For example, in a motor whose lower value is 230 V, each coil is designed to see 230 V; on a 400 V line in star, each coil again gets about 230 V. In a motor whose lower value is 400 V, the coils are built for 400 V and receive the full voltage when the motor is delta-connected to 400 V.

Choice according to the panel arrangement

  • Direct start with contactor and protection: Either rating can be used; connect as shown on the nameplate.
  • Star-delta starter: The motor must be able to operate delta-connected at 400 V; this is only possible if the first value on the nameplate is 400 V.
  • Frequency inverter with single-phase input (230 V output): The delta connection of a motor whose first nameplate value is 230 V suits this output.
  • Drive with three-phase input (400 V output): Either rating can work with the appropriate connection.

In the DRG range, power determines the rating

On DRG models the rating is set by power group: small models up to and including 3 kW are rated 230/400 V, larger ones 400/690 V. So on a 400 V network you usually do not need to choose a voltage separately; the rating follows whichever group the required power falls into. If you are looking for a motor of 3 kW or less for a star-delta panel, mention this before ordering. How the connection is actually made depends on the motor nameplate, the manufacturer's documentation and the judgement of qualified electrical personnel.

You can read about connection concepts in the article on terminal and star-delta connection, and review models whose voltage is stated on every product page in the shop listing.