GE Multilin
L90 Line Current Differential System
5-85
5 SETTINGS
5.4 SYSTEM SETUP
5
Figure 5–20: CHARGING CURRENT COMPENSATION CONFIGURATIONS
•
POSITIVE and ZERO SEQUENCE CAPACITIVE REACTANCE:
The values of positive and zero-sequence capacitive
reactance of the protected line are required for charging current compensation calculations. The line capacitive reac-
tance values should be entered in
primary kohms
for the total line length. Details of the charging current compensa-
tion algorithm can be found in Chapter 8:
Theory of operation
.
If shunt reactors are also installed on the line, the resulting value entered in the
POS SEQ CAPACITIVE REACTANCE
and
ZERO SEQ CAPACITIVE REACTANCE
settings should be calculated as follows:
1.
Three-reactor arrangement:
three identical line reactors (
X
react
) solidly connected phase to ground:
(EQ 5.8)
2.
Four-reactor arrangement:
three identical line reactors (
X
react
) wye-connected with the fourth reactor (
X
react_n
)
connected between reactor-bank neutral and the ground.
(EQ 5.9)
X
1line_capac
= the total line positive-sequence capacitive reactance
X
0line_capac
= the total line zero-sequence capacitive reactance
X
react
= the total reactor inductive reactance per phase. If identical reactors are installed at both line ends, the
value of the inductive reactance is divided by 2 (or 3 for a three-terminal line) before using in the above
equations. If the reactors installed at both ends of the line are different, the following equations apply:
1.
For 2 terminal line:
2.
For 3 terminal line:
X
react_n
=
the total neutral reactor inductive reactance. If identical reactors are installed at both line ends, the
value of the inductive reactance is divided by 2 (or 3 for a three-terminal line) before using in the above
equations. If the reactors installed at both ends of the line are different, the following equations apply:
1.
For 2 terminal line:
2.
For 3 terminal line:
Charging current compensation calculations should be performed for an arrangement where the VTs are con-
nected to the line side of the circuit; otherwise, opening the breaker at one end of the line will cause a calcula-
tion error.
Differential current is significantly decreased when
CHARGING CURRENT COMPENSATION
is “Enabled” and the
proper reactance values are entered. The effect of charging current compensation is viewed in the
METERING
87L DIFFERENTIAL CURRENT
actual values menu. This effect is very dependent on CT and VT accuracy.
Possible 3-Reactor
arrangement
Line Capacitive Reactance
Xreact
Xreact
Xreact_n
X1line_capac
X0line_capac
Possible 4-Reactor
arrangement
A B C
A B C
831731A3.CDR
X
C
1
X
1line_capac
X
react
X
react
X
1line_capac
–
------------------------------------------------
=
,
X
C
0
X
0line_capac
X
react
X
react
X
0line_capac
–
------------------------------------------------
=
X
C
1
X
1line_capac
X
react
X
react
X
1line_capac
–
------------------------------------------------
=
,
X
C
0
X
0line_capac
X
react
3
+
X
react_n
X
react
3
+
X
react_n
X
0line_capac
–
---------------------------------------------------------------------------------
=
X
react
1
1
X
react_terminal1
-----------------------------------
1
X
react_terminal2
-----------------------------------
+
=
X
react
1
1
X
react_terminal1
-----------------------------------
1
X
react_terminal2
-----------------------------------
1
X
react_terminal3
-----------------------------------
+
+
=
X
react_n
1
1
X
react_n_terminal1
----------------------------------------
1
X
react_n_terminal2
----------------------------------------
+
=
X
react_n
1
1
X
react_n_terminal1
----------------------------------------
1
X
react__n_terminal2
------------------------------------------
1
X
react_n_terminal3
----------------------------------------
+
+
=
NOTE
NOTE
Summary of Contents for UR Series L90
Page 652: ...A 16 L90 Line Current Differential System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 772: ...B 120 L90 Line Current Differential System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 802: ...C 30 L90 Line Current Differential System GE Multilin C 7 LOGICAL NODES APPENDIX C C ...
Page 812: ...D 10 L90 Line Current Differential System GE Multilin D 1 IEC 60870 5 104 APPENDIX D D ...
Page 824: ...E 12 L90 Line Current Differential System GE Multilin E 2 DNP POINT LISTS APPENDIX E E ...
Page 834: ...F 10 L90 Line Current Differential System GE Multilin F 3 WARRANTY APPENDIX F F ...
Page 846: ...xii L90 Line Current Differential System GE Multilin INDEX ...
