Siemens 7SJ82 Manual page 1039

Capacitor-bank tap voltage as phase-to-phase voltage:
(it equals a phase-to-ground voltage of 13.28 kV)
Voltage matching factors are set as:
The voltage measuring points must be set as indicated in the figure:
Busbar transformer, rated primary voltage:
Busbar transformer, rated secondary voltage:
Transformer to tap the voltage, rated primary voltage:
Transformer to tap the voltage, rated secondary voltage:
Under normal operation, these settings result in a differential voltage of approximately 0 V and in the primary
and secondary measured voltage values as indicated in the
NOTE
i
i
The sound secondary tap voltage must not be smaller than 1 V. Otherwise the function cannot work prop-
erly. Fulfill this condition by applying an appropriate voltage transformer for the tap voltage. Siemens
recommends applying a tap voltage transformer which provides under normal operation a secondary
voltage in the area of the rated secondary voltage.
EXAMPLE
In the grounded system:
Ratio of the capacitor-bank busbar voltage to the tap voltage (matching
factor k):
Busbar transformer, rated primary voltage:
Busbar transformer, rated secondary voltage:
To ensure an optimal tap-voltage measurement, the following transformer ratio is recommended:
Transformer to tap the voltage, rated primary voltage:
Transformer to tap the voltage, rated secondary voltage:
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
7.7 Voltage Differential Protection for Capacitors
23 kV
345 kV/23 kV = 15
345 kV
110 V
22 kV
110 V
7.7.3.1 Description.
400 kV/400 V = 1000
400 kV
100 V
400 V
100 V
Capacitor Bank Protection
1039