The synchronous impedance method or Emf method is based on the concept of replacing the effect of the armature reaction with an imaginary reactance. To calculate the regulation, the synchronous method requires the following data: They are the armature resistance per phase and the open circuit characteristic. The open circuit characteristic is the graph of circuit voltage and field current. This method also requires a short circuit characteristic which is the graph of the short circuit and the field current.
Synchronous impedance measurement
The measurement of the synchronous impedance is performed by the following methods. They are known as
DC resistance test
Open circuit test
Short circuit test