Reliability of transmission by means of line impedance and K-Factor measurement

Distance relays are important elements for the reliability of electrical power transmission. The Positive Sequence Impedance and the Ground Impedance Matching Factor, or k-Factor, as it is often referred to, are some of the most important settings of such a relay. Should one of these settings be done improperly, the whole investment in protection from instrument transformers over the relay up to the circuit breaker is not used as efficient as it could be. This paper explains the difficulty of k-Factor settings and points out cost effective solutions for preventing incorrect behaviour of distance protection schemes.