A triple-speed electric motor is a three-phase motor that can be established in two ways, with three separate windings or with a common winding with a Dahlander.
Dahlander electric motor is a motor that has special winding that can receive two different locks, with the number of poles changed, creating two distinct speeds.
The three-phase electric motor has different but constant speeds on the same axis. They are for just a voltage value, and the available relays generally allow only the exchange of speeds. The power and current for each rotation will be different, and varies according to the load, and this can be solved through a frequency inverter.
It is important that the Dahlander winding is opened, otherwise, induced currents will appear when the common winding is supplied, which will influence the operation of the motor. The reason we avoid this is that these motors have the system of a three-phase transformer.
The electric motors with three windings are closed in star which avoids the same problems and in case they need the triangle connection, the possibility of interrupting them when not being fed is mandatory. https://www.mrosupply.com/bearings/cylindrical-roller-bearings/2070355_nj-2220-ecpc3_skf-bearing/