Page 336 - Practical Power System and Protective Relays Commissioning

Protective Relays Testing and Commissioning Chapter | 20 331

1. Relay data:
11 kV OC relay I set 5 1.2 I n
CT ratio 5 1000/1 relay characteristic used 5 SI
TD 5 1 I set 5 6 I n
Relay characteristic angle 5 45 degrees current logging voltage- (90
degrees connection relay), as shown in Fig. 20.2.4.
Test the relay pickup/drop out and characteristic times and instantaneous
current as per the tests done in Section 20.2.1.1 for nondirectional OC relay
considering an injection of polarizing voltage and current with an angle in
the operating zone.
For testing of the directional unit in phase (R) of the relay, inject a
current greater than the pickup value, with a polarizing voltage from phase
Y and B, then check the operating boundaries of the relay between lag
135 degrees and lead 45 degrees. Check that the error in angle is about 6 5
degrees, then fill in the test sheet in Table 20.2.2.

FIGURE 20.2.4 Relay characteristic of directional OC relay.

TABLE 20.2.2 Relay Test Sheet 2

Relay Characteristic Angle 45 Degrees
Boundaries lag
Boundaries lead