EQUATION2093-ANSI V1 EN-US (Equation 128)
EQUATION2095-ANSI V1 EN-US (Equation 129)
(for the purposes of this test procedure)
Therfore:
_ 2Ci Icc i Xi V Vset× × > -
EQUATION2097-ANSI V1 EN-US (Equation 130)
( )
( )
2
_
V Vset
Icc i
Ci Xi
-
>
×
EQUATION2099-ANSI V1 EN-US (Equation 131)
10. Using the settings for VSet, VDeadband, C (Compensating factor) and Xr2 (transformer short circuit
impedance) calculate the magnitude of Icc_i necessary to cause a tap change command.
11. Inject current equal to I2Base for Transformer 1 and (I2Base - |Icc_i|) for Transformer 2 so that the
magnitude of calculated circulating current will cause a raise command to be issued for
Transformer 2 and a lower command for Transformer 1. Magnitude and direction of circulating
currents measured for each transformer can be observed as service values on the local HMI and
raise/lower commands detected from the binary output mapped in the Signal Matrix.
The voltage injection equal to
VSet is required for both transformers during this
test.
12. Confirm that a tap change command is issued from the voltage control function to compensate for
the circulating current.
13. Injected currents can be reversed such that the direction of calculated circulating currents change
polarity, which will cause a lower command for Transformer 2 and a raise command for
Transformer 1.
Circulating current limit
SEMOD175185-841 v6
1. Confirm that OperationPAR is set to CC for each transformer in the parallel group.
2. Confirm that OperCCBlock is set to Enable for each transformer in the parallel group.
3. Review the setting for CircCurrLimit.
4. Review the setting for CircCurrBk to confirm whether a circulating current limit will result in an
Alarm state, Auto Block or Auto&Man Block of the automatic voltage control for tap changer, for
parallel control function TR8ATCC (90).
5. Inject a voltage V
B
equal to VSet for each transformer.
6. Inject a load current for Transformer 1 that is equal to rated load current I2Base and a load current
for Transformer 2 that is 1% less than (I2Base – (I2Base · CircCurrLimit))
7. Confirm that the automatic voltage control for tap changer, for parallel control function TR8ATCC
(90) responds in accordance with the setting for CircCurrBk. Alarm and blocking conditions can be
confirmed through interrogation of the event menu or the control menu on the local HMI.
1MRK 504 165-UUS Rev. J Section 11
Testing functionality by secondary injection
Transformer protection RET670 261
Commissioning manual
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