The field winding in the synchronous machine is in the rotor, the rotating part of the motor and the winding of the armature are in the stator, stationary part. The rotor in the synchronous machines may be of the protruding or smooth type. The rotor of the synchronous machine rotates at a constant speed in steady state and this is the main characteristic for these machines. The rotating magnetic field, resulting from the interaction between the driving magneto forces due to three-phase sine-wave alternating currents, rotates at the same speed as the rotor. The rotational speed of the rotor and the rotating magnetic field is called the synchronous speed.
The field winding is fed with direct current giving the magnetic flux in the air gap. This feed is mainly achieved by two rotating collector rings, located on the rotor shaft, which make contact with fixed brushes. The excitation can be done by a direct current network or by a rectified alternating current network. Synchronous electric motors are used primarily as generating units in hydroelectric power plants, nuclear or thermoelectric power plants. Large synchronous motors are used as pumps and in fractional power applications such as electric clocks, timers and other applications. best options for vem3709t