Page 363 - Practical Power System and Protective Relays Commissioning

358 Practical Power System and Protective Relays Commissioning

TABLE 20.7.1 Differential Voltage Pickup Test
ΔV% φ (degrees) Running Incoming V 1 V 2
Set Voltage V 1 Voltage V 2 Pickup Pickup
5% 5 63.5 63.5
7.5% 5 63.5 63.5
10% 5 63.5 63.5

TABLE 20.7.2 Differential Angular Pickup Test

Δφ Set (degrees) V Line V 2 V Bus V 2 Phase Angle Pickup
Lead Side Lag Side
10 63.5 63.5
20 63.5 63.5
30 63.5 63.5

TABLE 20.7.3 Differential Frequency Pickup Test

ΔF Set V 1 V 2 Δφ (degrees) ΔF Pickup
20 mH 63.5 63.5 10

4. Blocking voltage test
Reduce the bus voltage and line voltage to 45% of V n -28.575 V.
Then check that the relay will block operation at this level of voltage and
below, and that it will operate above this voltage.
5. Check the live and dead voltage monitor for bus and line voltage
This feature monitors the running and incoming voltage and considers the
line live for voltages above 55% V n and considers the line dead for voltages
less than 25 %V n . The same applies for the bus voltage monitor. This feature
allows bypassing of the synchronizing operation for dead conditions of the
line or bus.