Page 343 - Practical Power System and Protective Relays Commissioning

338 Practical Power System and Protective Relays Commissioning

FIGURE 20.3.5 Distance relay directionality test.

connection to the correct direction—normally (Line Side LS) as per the set-
ting in distance protection. Then we repeat the test and measure again to be
sure that the direction is correct.
There is also in the market a tester which can do this test when connected
to the secondary currents and voltages of the relay.
10. Tele protection scheme test
a. Tripping scheme.
Permissive underreach scheme test.
Permissive overreach scheme test.
Direct transfer trip test.
b. Blocking scheme.
Permissive overreach scheme test.
Each scheme tripping and logic scheme is simulated by injecting the
required zone fault and simulating the received signal.
Also, a directional earth fault protection scheme will be simulated.
During a distance protection scheme test the earth fault protection func-
tion should be switched off, also during the Directional Earth Fault (DEF)
scheme test the distance protection function should be switched off.
11. Autoreclose scheme tests

A simulation test will be done to check the following:
Dead time (time between Auto-Reclosure (A/R) start and reclosing shot).
Reclaim time (time between the first close command and the recloser to
be in ready condition).
External autoreclosure on/off control.
External A/R blocking.
A/R blocking for an open CB closing on to a fault.
A/R blocking for CB in a not-ready condition.
A/R blocking due to lack of synchronization verification.
Operation counter check.