Operation of synchronous motors at constant leading power factor is one of the operation modes, for which synchronous motors may be designed, under this mode of operation, the gene ration of reactive power is directly proportional to the active power consumed by the motor. A static excitation arrangement, including an uncontrolled rectifier and a compounding transformer, is one of control systems which are suggested for holding the motor power factor constant.
This paper demonstrates the mechanism of self controllability performed by the compounding transformer which has been modified and constructed in the Electrical Engineering Department, EL-Mansoura University. In addition, the paper gives a suggested equivalent-circuit of the transformer and the corresponding vector diagrams: both at no-load and under load conditions. There by the proper compounding effect can be determined.
Results of the laboratory investigations carried out on the test model has been discussed and compared with those obtained under manual control. The self controllability showed by the system in holding the motor power-factor constant, irrespective of the load variation, is a major advantage which may be added to its reliability and simplicity.