Determination of the Earth Fault Factor in Power Systems for Different Earthed Neutrals

Abstract

This paper presents an analytical method to

calculate the earth fault factor (EFF) in power systems, under

different neutral earthed possibilities. The magnitude of the EFF

depends on the way the neutrals of a system are earthed and

influences some important aspects in power systems as the

sensitivity and selectivity of relays, the value of short-circuit

currents, the overvoltage between lines and earth, the

determination of arrester rating and the system insulation level.

The obtained results are compared with the values of EFF

referred in International Standards. The application of the

proposed study is discussed.