Page 345 - Practical Power System and Protective Relays Commissioning

340 Practical Power System and Protective Relays Commissioning

FIGURE 20.4.2 Pilot wire line differential protection for AC and DC circuits.

TABLE 20.4.1 Test Sheet 1
Injected Relay Operation Current Relay Operation Current
Phase End A End B
R N
Y N
B N
R Y
Y B
B R

operates. Repeat this test for the other two phases, then repeat the test for
phase phase injection and measure the value at which the relay will operate,
as shown in Fig. 20.4.2 and Table 20.4.1.
Repeat the above test, but put back the trip links and check the value of
the current at which the relay will trip at one phase at least, and check the
same at the other end of the line.