How does synchronous motor work?
Simplest synchronous motor: The stator is an electromagnet, fed with alternating current. The armature is a permanent magnet. The polarity of the stator reverses in time with the supply current, thus alternately attracting and repelling the armature. The speed of the motor depends on the frequency of the supply current. Unfortunately, that simple synchronous motor may start up in either direction. (Whichever direction it is going in, it will stay going that way)) Sometimes that’s not important, if you only want something to be going round but don’t care which way (microwave oven turntable, for instance) and sometimes it’s a positive advantage (such a motor will automatically reverse direction if it hits up against an obstruction). Sometimes it gets taken care of anyway (with an electric clock, the first thing you’re going to do when it’s plugged in is set the time, which involves manually turning the motor. As long as the last change you make is to advance the hands, the clock will con
