Generator Excitation System is used to provide the DC supply to the field winding for producing the magnetic field in the generator. It is considered as a main part and backbone of the generator. Excitation system also provides stability of the power system by controlling the system voltages which can be enhanced for considering some key factors. In this paper performance evaluation of new static excitation system of Tarbela power station has been carried out. In Tarbela there are two types of Excitation for different generating units i.e. rotary and Static Excitation system. In this paper different test results of new state of the art static excitation system has been presented and compared with the rotary excitation system. Some new features of static excitation system are also discussed for improving the response and stability of the power system.