Current, Voltage, And Phase Rotation Testing - Siemens SIPROTEC 7SJ62 Manual

3.3.6

Current, Voltage, and Phase Rotation Testing

≥ 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.
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.
Voltage Transformer Miniature Circuit Breaker (VT mcb)
The VT mcb of the feeder (if used) must be opened. The measured voltages in the operational measured
values appear with a value close to zero (small measured voltages are of no consequence).
Check in the spontaneous annunciations that the VT mcb trip was entered (annunciation „>FAIL:FEEDER
VT" „ON" in the spontaneous annunciations). Beforehand it has to be assured that the position of the VT mcb
is connected to the device via a binary input.
Close the VT mcb again: The above messages appear under the spontaneous messages as „OFF", i.e.
„>FAIL:FEEDER VT" „OFF".
If one of the events does not appear, the connection and allocation of these signals must be checked.
If the „ON"-state and „OFF"–state are swapped, the contact type (H–active or L–active) must be checked and
remedied.
only 7SJ623, 7SJ624 and 7SJ64
If with 7SJ623, 7SJ624 or 7SJ64 a busbar voltage is used for input V
the assigned VT mcb is connected to the device, the following function must also be checked:
If the VT mcb is open the annunciation „>FAIL: BUS VT" „ON" appears, if it is closed the annunciation
„>FAIL: BUS VT" „OFF" is displayed.
Switch off the protected power line.
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
Mounting and Commissioning
3.3 Commissioning
(for voltage or synchronism check) and
4
451