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3
3.1
3.1.1
60
Current reversal and weak end infeed
logic for distance protection (ZCAL)
Current reversal and weak end infeed logic for
distance protection (ZCAL)
Prepare the terminal for verification of settings as outlined in section "Preparing for
test" in this chapter.
The testing instructions are related to each separate phase, when phase segregated
scheme communication logic ZC1P is used. Only one type of fault is necessary, when
three-phase scheme communication logic ZCOM is used.
The current reversal logic and the week end infeed functions are tested during the sec-
ondary injection test of the impedance measuring zones together with the scheme com-
munication logic for the distance protection function (ZCOM or ZC1P).
Current reversal logic
It is possible to check the delay of the ZCOM-CS (ZC1P-CSLn) carrier send signal with
tDelay by changing from a reverse to a forward fault.
By continuously activating the ZCOM-CR (ZC1P-CRLn) input and changing from a re-
verse to a forward fault, the delay tDelay can be checked.
Checking of current reversal
Note!
The reverse zone timer must not operate before the forward zone fault is applied. The
user might need to block the reverse zone timer during testing of current reversal.
Note!
The forward zone timer must be set longer than 90 ms.
Procedure
1.
Activate the carrier receive (ZCOM-CRLn) signal.
2.
Set the healthy condition to an impedance at 50% of the reach
of the reverse zone connected to ZCAL-IRVLn.
3.
After the start condition is obtained for reverse zone, apply a
fault at 50% of the reach of the forward zone connected to
ZCAL-WEIBLKLn.
Chapter 10
Verifying settings by secondary
injection
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