Pumps, wherein two speeds can be used to control the output flow.Pole changing motors are normally used in applications where two speed controls are necessary. However, the Dahlander motor has the disadvantage of fast mechanical wear and tear due to changing speeds in such a drastic ratio this type of connection also produces high harmonic distortion during the shifting of poles as the angular distance between the power generated increases as the poles are decreased in the motor. The system is much simpler and easier to use compared to other speed control methods available. This is because most of the power is used to drive the motor and no electrical pulse switching is done. Advantages and disadvantages ĭahlander motors have advantages compared to other speed control systems like variable frequency drives, as there is less power loss. Star connections ( Y) varied to double star connections (YY) are used for quadratic torque applications, such as pumps. Normally, the electrical configuration of windings is varied from a delta connection (Δ) to a double star connection (YY) configuration in order to change the speed of the motor for constant torque applications, such as the hoists in cranes.

The poles can be varied at a ratio of 1:2 and thus the speed can be varied at 2:1. Some smaller induction motors are connected so that all the poles are identical, causing the motor to act as though there is an equal number of opposite poles in between.Ī Dahlander motor achieves different speeds by switching the configuration of the electrical windings, indirectly adding or removing poles and thus varying the rotor speed. N s = Synchronous speed, in revolutions per minute f = AC power frequency p = Number of poles per phase winding Ī regular induction motor has an equal number of opposite poles that is, at any instant, there are an equal number of North and South magnetic poles. The primary factor in determining the speed of an induction motor is the number of poles, given by the formula The Dahlander motor is based on a 'consequent pole' connection. Dahlander motor wiring for low speed ( delta connection) and high speed (double star connection)

Motor winding diagram