Polarity Check For The Voltage Input U 4 - Siemens siprotec 7SA6 User Manual

Installation and Commissioning
8.3.8 Polarity check for the voltage input U
Only for
Synchronism
Check
8-50
All six measured loops must have the same impedance components (R and X). Small
variations may result due to the non-symmetry of the measured values. In addition the
following applies for all impedances when the load is in the first quadrant:
R, X both positive, when power flows into the line,
R, X both negative, when power flows towards the busbar.
The general case is assumed here, whereby the forward direction (measuring
direction) extends from the busbar towards the line. In the case of capacitive load,
caused by e.g. underexcited generators or charging currents, the X-components may
all have the opposite sign.
If significant differences in the values of the various loops are present, or if the
individual signs are different, then individual phases in the current or voltage
transformer circuits are swapped, not connected correctly, or the phase allocation is
incorrect. After isolation of the line and short-circuiting of the current transformers the
connections must be checked and corrected. The measurement must then be
repeated.
Finally the power line is again isolated.
Depending on the application of the voltage measuring input U
be necessary. If no measuring voltage is connected to this input, this subsection is
irrelevant.
If the input U is used for measuring a voltage for overvoltage protection (Power
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System Data 1 address  8 WUDQVIRUPHU = 8[ WUDQVIRUPHU), no polarity
check is necessary because the polarity is irrelevant here. The voltage magnitude was
checked according to Subsection 8.3.6.
If the input U is used for measuring the displacement voltage Uen (power system data
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1 address  8 WUDQVIRUPHU = 8GHOWD WUDQVI), the polarity is checked
together with the measured current test according to Subsection 8.3.10.
If the input U is used for measuring a busbar voltage for synchronism check (power
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system data 1 address  8 WUDQVIRUPHU = 8V\QF WUDQVI), the polarity
must be checked as follows using the synchronism check function.
The device must be equipped with the synchronism and voltage check (dead-line/
dead-bus check) function which must be configured to HQDEOHG under address 
(see section 5.1).
The voltage 8V\QF connected to the busbar must be specified correctly under
address  8V\QF FRQQHFW (see Subsection 6.1.1).
If there is no transformer between the two measuring points, address $
ϕ 8V\QF8OLQH must be set to ƒ (see Subsection 6.1.1).
If the measurement is made across a transformer, this angle must correspond to the
phase rotation through which the vector group of the transformer as seen from the
feeder in the direction of the busbar rotates the voltage. An example is shown in
Subsection 6.1.1.
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, a polarity check may
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7SA6 Manual
C53000-G1176-C133-1