Mounting and Commissioning
3.3 Commissioning
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
323
3.3.7 Current, Voltage, and Phase Rotation Testing
Preliminary Remark
Note
The voltage and phase rotation test is only relevant for devices with voltage transformers.
≥ 10 % of Load Current
The connections of the current and voltage transformers are tested using primary quantities. Secondary load
current of at least 10 % of the nominal current of the device is necessary. The line is energized and will remain
in this state during the measurements.
With proper connections of the measuring circuits, none of the measured-values supervision elements in the
device should pick up. If an element detects a problem, the causes which provoked it may be viewed in the
Event Log. If current or voltage summation errors occur, then check the matching factors.
Messages from the symmetry monitoring could occur because there actually are asymmetrical conditions in
the network. If these asymmetrical conditions are normal service conditions, the corresponding monitoring
functions should be made less sensitive.
Current and Voltage Values
Currents and voltages can be seen in the display field on the front of the device or the operator interface via a
PC. They can be compared to the quantities measured by an independent source, as primary and secondary
quantities.
If the measured values are not plausible, the connection must be checked and corrected after the line has been
isolated and the current transformer circuits have been short-circuited. The measurements must then be re-
peated.
Note
If the voltage measurement is carried out via feed through capacitances, the display of the values of the phase-
to-ground voltages and phase angle between the phase-to-ground voltages and the phase currents can be
used to optimize the configured capacitance values afterwards and to achieve an improvement of the measur-
ing accuracy. An explanation of the procedure for optimizing the input capacitances is to be found in Section
2.1.3.2, „Capacitive Voltage Measurement“.
Phase Rotation
The phase rotation must correspond to the configured phase rotation, in general a clockwise phase rotation. If
the system has an anti-clockwise phase rotation, this must have been considered when the power system data
was set (address 209 PHASE SEQ.). If the phase rotation is incorrect, the alarm „Fail Ph. Seq.“ (FNo
171) is generated. The measured value phase allocation must be checked and corrected, if required, after the
line has been isolated and current transformers have been short-circuited. The measurement must then be re-
peated.
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