AC motors can be designed to operate at multiple speeds. A Consequent-Pole motor is a motor with stator windings than can be connected in two or more different ways so that the number of stator poles can be changed. Since the speed of an induction motor depends on the number of poles in the stator, most consequent-pole motors have two speeds, one of which is half of the other. By physically reconnecting the leads, a 2:1 speed ratio can be obtained. Typical synchronous speeds for 60-Hz ac motors are: 3,600/1,800 rpm (2/4 pole), 1,800/900 rpm (4/8 pole), and 1,200/600 rpm (6/12 pole).

 

The stator leads of a consequent-pole motor are brought out of the motor and connected in different ways to create different numbers of poles. The current can be made to travel through windings connected in series or parallel with each other. A series connection of two windings has one pole. The current flows through both coils in the same direction, so both coils have the same polarity. The poles merge since they are adjacent. The same windings connected in parallel have two poles. The current flows through the coils in opposite directions, so the coils have opposite poles. The poles are separate since they are opposite. Therefore a motor wired with two poles when wired in series has four poles when wired in parallel.