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Mounting and Commissioning
3.3 Commissioning
Implementation of Zero Sequence Current Tests
For these commissioning tests, the zero sequence current must be at least 2 % of the rated relay current for
each phase, i.e. the test current at least 6 %.
This test cannot replace visual inspection of the correct current transformer connections. Therefore, the
inspection of these connections is a prerequisite.
•
Switch on test current.
•
Read out the current magnitudes:
Compare the indicated current magnitudes under Measurement → Secondary → Operational meas-
ured values secondary with the actually flowing values:
–
All phase currents of the tested measuring location correspond to approximately
current (for 1-phase transformers
–
3Ι0 of the tested measuring location corresponds to the test current.
–
Phase currents and zero sequence current of the other measuring location are, on transformers,
nearly 0.
–
The current at the auxiliary 1-phase current input corresponds to the test current — provided this
current is available and included.
Deviation can practically occur only for the single-phase current (if included) because the connection of
the phase currents had been verified already during the symmetrical tests. In case of deviations:
–
Switch off the test source and the protected object (shut down the generator) and earth it.
–
Re-check the assignment or the tested 1-phase input (Section
margin heading "Assignment of Auxiliary 1-phase Measuring Locations").
–
Re-check the settings for the magnitude matching (Section
margin heading "Current Transformer Data for 1-phase Auxiliary Current Inputs").
Parameter für die Betragsanpassung überprüfen (Abschnitt
titel "Stromwandlerdaten für 1-phasige Zusatzeingänge").
–
Check the plant connections to the device and the test arrangement and correct them.
–
Repeat test and re-check the current magnitudes.
Measuring Differential and Restraint Currents
The differential and restraint currents are referred to the rated currents of the tested side of the main
protected object. If a zero sequence current test does not concern the main protected object but a different
earthed object (e.g. a shunt reactor outside the main object), the base of the referred currents is the rated
current of that 3- phase measuring location to which the 1-phase current input is assigned, i.e. the measuring
location under test. This must be considered when they are compared with the test currents.
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),
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2.1.4 Power System Data 1
2.1.4 Power System Data 1
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of the test
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2.1.4 Power System Data 1
under
unter Rand-
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
under
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