Siemens 7SJ82 - Page 1034

matching factor phase-selectively using the parameters Volt. match. factor phs A, Volt. match.
factor phs B, and Volt. match. factor phs C, or to set it for all phases together using the param-
eter Voltage matching factor. If the compensation is carried out, the function obtains the matching
factors from the compensation functionality instead of applying the setting values. In case the compensation
is reset, the setting values are applied again.
Calculation of the Differential Voltage
The calculation of the differential voltage depends on the way the capacitor-bank neutral point is grounded.
With the parameter Cap.-bank neutral point, you can set the grounding type.
2 ways of capacitor-bank neutral-point grounding are possible:
•
Grounded capacitor-bank system
[dw_voltage_measurement_grounded, 1, en_US]
Figure 7-38 Voltage Measurement for a Grounded Capacitor-Bank System
The following formula is used to calculate the differential voltage V
diff.
of phase A:
V
diff,A
= |V
BB,A
- k
A
⋅ V
tap,A
|
V
BB,A
Voltage from the busbar, phase A
V
tap,A
Voltage from the tap, phase A
k
A
Voltage matching factor, phase A
This calculation also applies to the calculation of the V
diff.
of phase B and phase C.
The voltage measuring-points are connected to the corresponding function-group interfaces.
[Sc_grounded_ground, 1, en_US]
Figure 7-39 Connecting Measuring Points to the Capacitor Bank Function Group for the Grounded Capac-
itor-Bank System
•
Isolated capacitor-bank system
Capacitor Bank Protection
7.7 Voltage Differential Protection for Capacitors
1034 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017