Verifying The Signals And Settings For Compensated And High Impedance Earthed Systems - Hitachi RER670 Commissioning Manual

Section 10
Testing functionality by secondary injection
10.4.2.3 Verifying the signals and settings for compensated and high impedance
earthed systems
Testig the underimpedance starting element
Measure operating characteristics during constant current conditions. Keep the measured current as
close as possible to its rated value or lower. But make sure it is higher than the set minimum
operating current.
Ensure that the maximum continuous current to the IED does not exceed four times its rated value, if
the measurement of the operating characteristics runs under constant voltage conditions.
The test procedure has to take into consideration that the shaped load encroachment characteristic
is active. It is therefore necessary to check the setting. To verify the settings with the shaped load
encroachment characteristic, the test should be carried out according to figures mentioned below. In
cases where the load encroachment characteristic is not activated, tests according to the adjusted
figures should be carried out.
To verify the settings, the operating points according to the following fault types should be tested:
• One phase-to-earth fault
• One phase-to-phase fault
Circular characteristic
Set Operation to On always to check for performance of distance protection during testing.
Select type of earthing system by setting parameter SystemEarthing and set to either Compensated
or High impedance. Also, Select CharStartZ< to Circular and set OpLoadEnch to On. Set
Z1CircleStart, LineAng and ArgLd to default values. Also, set RLd such that its value is lower than
Z1CircleStart, that is, encroached into operating region.
Phase-to-earth fault
Test points that are to be considered for measurement accuracy of set impedance reach are shown
in Figure
84
19 and Table 21.
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Commissioning manual