Determination of Proper Angle Settings for Resistance Grounded Distribution Systems for Directional Earth Fault Relays

The intensive use of the underground cables in distribution systems causes the total phase-ground capacity of the system to increase. This situation causes the capacitive current based parallel tripping problem to occur frequently at the distribution system. Directional protection relays can be used to eliminate the problem and to protect the system selectively. However, it should be known selective operation of directional relays entirely depends on proper angle settings. In this study, angle setting of directional protection relays is utilise considering cable cross section, cable lenght, parallel feeders number and neutral grounding resistance. The efficiency of the selected angle adjustment methodology has been confirmed over the real distribution system.