Vt And Ct Setup - GE C70 Instruction Manual

9 APPLICATION OF SETTINGS
The CT and VT connections are shown in the figure above. The CT channels are connected as follows.
• The type 8L CT/VT module F1 to F3 three-phase CT channels are connected to the bus side three-phase CTs with a
120 / 5 A ratio.
• The type 8L CT/VT module U1 to U3 three-phase CT channels are connected to the neutral side window CTs with a
50 / 5 A ratio.
The following settings are applied in the EnerVista UR Setup software.
The VT channels are connected as follows.
• The type 8L CT/VT module F5 to F7 three-phase VT channels are connected to the bus side three-phase VTs with a
138 / 0.115 kV ratio.
• The type 8V CT/VT module M1 to M3 and M5 to M7 three-phase VT channels are connected to two tap VTs with a
1.25 / 0.25 kV ratio. The nominal voltage is calculated below for normal bank conditions and a nominal system voltage
of 138 kV (see impedance calculations the following sub-section).
The nominal bus phase VT voltage is:
The nominal tap VT voltage is:
Therefore, the tap VT secondary voltage is set as:
Where the VT ratio N is calculated as:
tap(VT)
The following settings are applied in the EnerVista UR Setup software.
GE Multilin
13800
--------------- -
V
=
 
tap bus
3
b

138000 Z
C
-------------------------------- -
V
=
 
tap nominal
t

3 Z
C
V

tap nominal
-------------------------------- -
V
=
 
tap secondary
N

tap VT
125 kV
------------------- -
N
=
 
tap VT
0.25 kV
C70 Capacitor Bank Protection and Control System
79674.34 V
=

13800 4.08
---------------------------------- -
171.41 V
= =

3 1894.42
171.41 V

----------------------- -
34.28 V
= =
5

5
=
9.4 SETTING EXAMPLE

9.4.2 VT AND CT SETUP

(EQ 9.1)
(EQ 9.2)
(EQ 9.3)
(EQ 9.4)
9-13
9