Excitation systemThe exciter is a synchronous generator with stationary salient poles (a stationary-field machine).its rotor is mounted on the shaft of the main generator.the rotor winding on the exciter produces the excitation energy which is rectified by rottating silicon diodes connected in a three-phase bridge circuit and fed to the fied winding of the main generator.the diodes are protected against excessive voltage peaks by means of varistor-type surge divertes.the fied winding inserted into the stator of the main machine.the actual value of voltage is picked off from the generator terminal and passed to the regulator.the setpoint is adjusted by means of a potentiometer and is continuosly being compared against the actual value. the excitation current required depends on the difference between actual value and setpoint.self excitation of the generator is assured by the presence of adequate amounte of remanence in the stator of the exciter. the voltage regulator is of compact and has been designed to offer good resistance to moisture and vibration.
* Dynamic voltage characteristicThe transient dip in voltage when rated load is placed on the generator at 0.8 power factor is 15 20% Us.the actual value depent onthe size of the generator itself.the recovery time is between 0.3 and 0.8 also depending on the size of the generator.* Control accuracyThe stedy-state control accurancy is +0.5% in the range from no-load,with constant power and a speed variation of up to 5%.* Parallel operationThe synchronus generator are suitable for operating in parallel with other machines of the same type,with other makers of generator and with the mains network,provided the necessry prerequisites are assign,when machines are running in parallel,the actual sharing of the active load is determined by the prime movers,the speed govermors of the paralleled prime movers must be set to provide the same characteristic.the generators are equipped with a reactive-current compensator to produce a suitable gradient for the voltage charactestic in isolated operation and specific value of reactive power when running in parallel with the mains network.Reactive power and power factor resaults from changes of voltage setting in parallel operation with mains network.