A triple-speed motor is a three-phase motor that can be basically arranged in two ways, with three separate windings or a common winding with a Dahlander. The Dahlander engine is a motor with special winding that can receive two different locks, in order to change the number of poles, thus creating two distinct speeds.
The three-phase electric motor 174658.00 leeson provides unequal speeds on the same axis, but constant and mostly for only one voltage value, because the available reconnections normally allow only the change of speeds. The power and the current for each rotation are different, being modified according to the intensity of the load, problem that can be solved through a frequency inverter.
It is of the utmost importance that the Dahlander winding be opened in the second case, otherwise, induced currents will appear when the common winding is fed, which will influence the operation of the motor. Therefore, they can not happen. The reason to avoid them is that these motors have precisely the system of a three-phase transformer. The electric motors with three windings are closed in star to avoid the same problems. If you need the triangle connection, it is mandatory to stop them when not being fed.