The three-phase synchronous engine is a distinctive and specialized electric motor. As the name suggests, this motor runs at a constant acceleration from no load to full load in synchronism with range Energy-conserving Vacuum Pump frequency. As in squirrel-cage induction motors, the speed of a synchronous electric motor is determined by the number of pairs of poles and the range frequency.
The operation of a typical three-phase synchronous motor could be summarized the following:
Three-stage AC voltage is put on the stator windings and a rotating magnetic field is produced.
DC voltage is applied to the rotor winding and a second magnetic field is usually produced.
The rotor then acts just like a magnet and is attracted by the rotating stator field.
This attraction exerts a torque on the rotor and causes it to rotate at the synchronous speed of the rotating stator field.
The rotor will not require the magnetic induction from the stator field for its excitation. As a result, the electric motor has zero slip when compared to induction electric motor, which requires slip in order to produce torque.
Synchronous motors are not self-starting and therefore require a method of bringing the rotor up to close to synchro nous speed before the rotor DC power is certainly used. Synchronous motors typically start as a normal squirrel cage induction engine through use of special rotor amortisseur windings. Also, there are two basic methods of offering excitation current to the rotor. One method is to use an external DC resource with current provided to the windings through slide rings. The other method is to really have the exciter installed on the common shaft of the electric motor. This arrangement does not require the use of slip rings and brushes.
A power system’s lagging power factor can be corrected by overexciting the rotor of a synchronous engine operating within the same system. This will produce a leading power element, canceling out the lagging power factor of the inductive loads. An underexcited DC field will create a lagging power element and because of this is seldom utilized. When the field is generally excited, the synchronous electric motor will run at a unity power element. Three-stage synchronous motors can be utilized for power aspect correction while at exactly the same time performing a major function, such as for example working a compressor. If mechanical power output is not needed, however, or could be provided in various other cost-effective ways, the synchronous machine continues to be useful as a “nonmotor” means of con trolling power element. It does the same job as a bank of static capacitors. Such a machine is called a synchronous condenser or capacitor.