Page 341 - Practical Power System and Protective Relays Commissioning

336 Practical Power System and Protective Relays Commissioning

FIGURE 20.3.3 Relay power swing characteristic.

The results in Table 20.3.3 should be verified as per the injected values
to the relay.

TABLE 20.3.3 Relay Test Sheet 2
Injected Impedance Relay Action Remarks
Z pass between Z ps and Z 3 Trip Yes Trip based on fault location
characteristic very fast with Z 1 or Z 2 or Z 3 as injected
Block No
fault
Trip No
Z pass between Z ps Block Z 1 and Z 2 and Z 3
characteristic and Z 3 Block Yes operation after 5 s
characteristic very slow

7. Switch on to fault instantaneous high-speed OC function test
During this test we will stop operation of the distance function to be
switched off and also backup OC function to be switched off.
We simulate this fault as a three-phase fault-close up to the relay location
for Example, closing of Transmission Line (TL) on a movable earth cables
put on three phases of the TL for maintenance purposes but forgotten on the
line after maintenance procedures are finished.
I pickup for Switch on to fault (SOTF) 5 0.1 A . 5% I N
As I N 5 1A