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7UT51 v3
If considerable deviations occur, recheck the
corresponding parameters and correct them where
necessary:
•
Address 1108, when the additional current input is
assigned to Winding 1 of a transformer
•
Address 1128, when the additional current input is
assigned to winding 2 of a transformer
•
Address 1148, when the additional current input is
assigned to winding 3 of a transformer
•
Address 1405, when the additional current input is
assigned to a virtual object.
Display of the phase angle between the star-point
current connected to input IA against the phase
current of Side 1, phase L1, L2, and L3 should be 0
when tested for IA-I1L1, IA-I1L2, and IA-I1L3,
respectively.
If installed on the winding of a transformer, and the
zero sequence current correction is used, the
differential and stabilizing currents of the differential
protection must be checked.
Page to Address 4161 to perform the differential and
stabilizing test. These values are referred to rated
current of the protected object.
Display of the differential current of the measuring
system L1, L2, and L3, referred to the rated current of
the protected object, should be negligible against the
magnitude of the line currents.
Display of the stabilizing (restraint) current of the
measuring system L1, L2, and L3, referred to the rated
current of the protected object, should be negligible
against the magnitude of the line currents.
If considerable differential currents occur, recheck the
concerned parameters for zero sequence current
processing and the matching factors:
•
Addresses 1106 to 1108 when the zero sequence
current is associated with Winding 1
•
Addresses 1126 to 1128 when the zero sequence
current is associated with winding 2
•
Addresses 1146 to 1188 when the zero sequence
current is associated with winding 3.
PRIM-2330C
Field Testing and Commissioning
If the differential current corresponds to 1/3 of the test
current, the star-point current correction is not
effective. If the differential current corresponds to 2/3
of the test current, the star-point current has wrong
polarity.
If the restricted ground-fault protection is not available
or not used, the zero sequence current tests are
complete. Disconnect the protected object and
ground, disconnect test arrangement and skip the next
test.
18.4.2
Current Test for Restricted
Ground Fault Protection,
Address Block 41
If the relay is equipped with restricted ground-fault
o
,
protection and is required in the application, a further
zero sequence current test must be carried out.
A renewed measurement of request of the operator is
necessary. The measured values are then stored but
not continuously actualized to ensure comparable
results. If this test arrangement is changed, a new
measurement request is necessary.
As soon as the first measured value appears in the
display, the test current can be switched off.
Go to Address 4100 and page to Address 4181 to test
the restricted ground-fault protection. Confirm with the
Yes key to begin measurement of all currents and
phase angles of this test.
Measurement of the Phase Current Relationship
During zero sequence current test, the three phase
currents must be approximately equal and without
phase difference. Otherwise wrong polarities are
present in the current transformer connections.
If one angle is 180
present:
•
Disconnect the protected object and ground
•
Check connections and test arrangement
•
Repeat test
o
o
instead of 0
, wrong polarity is
18
203
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