Turbine generator rotor double earth fault analysis

PowerGen has recently developed and tested a prototype device which is dedicated to detecting a turbine generator rotor double earth fault condition and raises a trip signal almost instantaneously. In spite of its speed of operation it is still essential to have a thorough understanding of the effect of a double earth fault so that the adequacy of the protection scheme can be judged for the likely range of operating conditions which may prevail. This paper describes the practical experiments and theoretical electromagnetic machine analysis which has given this understanding