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2.10.8 Tips to set the main/remote backup relays
To make the coordination between the main (primary) relay and backup relays on lines, using
a reach
1
setting and a delay timer setting
2
can resolve the problems. Figure 2.10-53 exemplifies
that respective reaches and delays in the distance protection (ZS/ZG) functions result in the
coordination between the main (primary) relay and backup relays on the lines.
Figure 2.10-53 Zones and time coordination between terminals
3
1
Note: For the ZS elements, the ‘reach’ setting is possible using the settings [Z*S-
Mho.Reach] and [Z*S-Mho.Angle] for the Mho characteristic. If the Quad
characteristic is applied, the value of the reach setting is projected on the
reactance-axis.
2
Note: To realize the coordination time interval (CTI), the user can apply delay times for
the operation in respective elements. For the ZS elements, for example, use the
settings [TZ*S].
3
Note: ‘Zone1’, ‘zone2’, and ‘zone3’ are zones seen by the ZS/ZG relays looking into the
forward. On the other hand, ‘zone4’ and ‘zone5’ are zones seen by the ZS/ZG relays
looking into the backward. The locations of the ZS/ZG relays are shown with
parentheses. That is, the zone1
(X)
, which is operated at the location X, trips ‘circuit
breaker
(X)
’.
(i) Setting for the primary line (Zone1)
The zone1 of the ZS/ZG function can be used as a backup relay substituted into the DIF (main)
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