ABB Relion 670 series, Installation And Commissioning Manual

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15.4.4.2 Completing the test
Continue to test another function or end the test by changing the Test mode setting
to Off . Restore connections and settings to their original values, if they were
changed for testing purposes.
15.5 Impedance protection
15.5.1 Full scheme distance protection, mho characteristic
ZMHPDIS
Prepare the IED for verification of settings outlined in section "Overview" and
section "Preparing for test" in this chapter.
Keep the current constant when measuring operating characteristics. Keep the
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 in an IED does not exceed four times
its rated value, if the measurement of the operating characteristics runs under
constant voltage conditions.
To verify the mho characteristic, at least two points should be tested.
In the following, three test points are proposed. The mho characteristic always goes
through the origin, which automatically gives a fourth point for the characteristic.
Section 15
1MRK 502 029-UEN A
Verifying settings by secondary injection
160
Installation and commissioning manual