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1MRK 504 165-UEN Rev. K
6.
Check that service value for voltage across SCB in phase L1, on the local HMI under Main
menu /Test is approximately 140%.
7.
Stop injection of all currents (that is, set all currents back to 0A).
8.
Check that all above mentioned function binary output signals now have logical value zero.
9.
Repeat above steps 1 - 8 for phase L2 and phase L3.
10.
Repeat above steps 1 - 8 to test different points from the above table.
Operation of this feature is based on internally calculated peak RMS voltage value. That means that
this feature is also able to operate for current signals with varying frequency. Note that for the
fundamental frequency injection, internally calculated voltage in percent corresponds directly to the
injected current value given in percent. However if it is required to test IDMT characteristic with a
varying frequency, the magnitude of the injected current must be adjusted accordingly. The following
formula can be used to calculate required current RMS value in percent at the desired injection
frequency in order to archive voltage percentage value given in the above table:
[ ]
I
%
inj
EQUATION2274 V1 EN-US
Above procedure can also be used to test definite time step. Pay attention that IDMT step can also
operate during such injection. Therefore make sure that appropriate settings are entered in order to
insure correct test results for definite time step.
11.5.16.2
Completing the test
Continue to test another functions 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. Make
sure that all built-in features for this function, which shall be in operation, are enabled and with
correct settings.
11.5.17
Negative-sequence time overcurrent protection for machines
NS2PTOC
11.5.17.1
Verifying settings by secondary injection
Transformer protection RET670
Commissioning manual
f
[ ]
%
=
injected
×
U
f
rated
Note that it is recommended to test IDMT operating times by injected current with the
rated frequency.
When inverse time overcurrent characteristic is selected, the operate time of the
stage will be the sum of the inverse time delay and the set definite time delay. Thus,
if only the inverse time delay is required, it is important to set the definite time delay
for that stage to zero.
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Section 11
Testing functionality by secondary injection
(Equation 94)
GUID-5AB7880E-629C-45E5-AF91-3EBDF19DEA79 v2
GUID-48A6DA1D-5CF5-4C1B-B1A4-3F2C73851FD4 v2
GUID-F7AA2194-4D1C-4475-8853-C7D064912614 v4
GUID-EB788169-532A-4A3E-BBEC-DCB28169DF86 v7
185
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