5.6  DISTANCE GROUND RELAYS

The instructions for adding a ground distance relay are the same as those for adding a phase distance relay.  See Section 5.7.

 

Also, the parameters of the distance ground relay are the same as those for the distance phase relay, with following exceptions:

1.   MinI, the minimum current threshold for a ground relay is the minimum ground current, 3Io in secondary amps, that is required to enable the pickup and tripping of the relay zones. You should enter a nonzero value here to avoid spurious operations.

2.   There are four additional parameters for the magnitude and angle of K1 and K2.  The parameter K is defined as (Zo-Z1)/(3Z1), where Zo and Z1 are the zero- and positive-sequence impedances of the transmission line, respectively. The parameter K1 is used for zone 1 only. The parameter K2 is used for the other zones.

3.   The Line Impedance button will show you the value of K1 for the primary line (the line on which the relay is located), as well as the value of K2 for the different remote lines.  Please refer to item 12: “Display Line Impedance” for Distance Phase Relays.

Note: When relay is on a line with multiple segments, the program will automatically trace the network topology to the true end of the line. See Section 8.9 for techniques for managing lines with multiple sections.