Siemens SIPROTEC 6MU805, Руководство пользователя, Страница: 25 / 162

Functions
2.1 General
SIPROTEC, 6MU805, Manual
C53000-G1140-C380-5, Release date 06.2018
21
Figure 2-1 Connection Principle for a Capacitive Voltage Measurement
In addition to the bushing capacitances, the line and stray capacitances also affect the measured voltage fed
to the protection device. These capacitances are primarily determined by the type and length of the connection
line.
The voltage inputs of the device have a resistive component of 1.2 M

Two capacitance values must be configured for each phase when using capacitive voltage measurement.
• The first value to be configured is the bushing capacitance (C
D,Lx
).
• The second value to be configured is the sum of the line and stray capacitance (C
S,Lx
).
The capacitances are configured as follows:
Boundary Conditions for the Capacitive Voltage Measurement
The voltages at the inputs of the protection devices depand on the primary rated voltage, the capacitances in
the power system and the impedances of the voltage inputs. The voltage V
sec, Lx
for phase Lx can be deter-
mined using the following formula:
Phase A 0241 Volt.trans.A:C1
0242 Volt.trans.A:C2 = C
D,A
= C
S,A
Phase B 0243 Volt.trans.B:C1
0244 Volt.trans.B:C2 = C
D,B
= C
S,B
Phase C 0245 Volt.trans.C:C1
0246 Volt.trans.C:C2 = C
D,C
= C
S,C
Phase Vx 0247 Volt.tran.Vx:C1
0248 Volt.tran.Vx:C2 = C
D,Vx
= C
S,Vx