ABB REL 505-C1 2.3 Series - Checking of Unblocking Logic; Completing the Test

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Scheme communication logic for distance
protection functions (ZCOM)
Chapter 10
Verifying settings by secondary
injection
8. Check that the no trip from scheme communication occurs.
9. Check that trip time from the forward directed zone used for
scheme communication tripping complies with the zone timer
and that correct trip outputs, external signals, and indication
are obtained for the actual type of fault generated.
14.4 Checking of unblocking logic
Check the unblocking function (if the function is required) when you check the com-
munication scheme.
14.4.1 Command function with continuous unblocking (Unblock = 1).
Procedure
1. Activate the carrier guard input signal (ZCOM-CRG) of the ter-
minal.
2. Using the scheme selected, check that a carrier accelerated
trip (ZCOM-TRIP) is obtained when the carrier guard signal is
deactivated.
14.5 Completing the test
Continue to test another function or complete the test by setting the test mode to off.