GE UR Series Instruction Manual Page 113

Line differential relay.

5 SETTINGS
NUMBER OF CHANNELS:
This setting should correspond to the type of communications module installed. If the relay is applied on two terminal lines
with a single communications channel, this setting should be selected as "1". For a two terminal line with a second redun-
dant channel for increased dependability, or for three terminal line applications, this setting should be selected as "2".
CHARGING CURRENT COMPENSATION:
This setting enables/disables the charging current calculations and corrections of current phasors. The following diagram
shows possible configurations.
Figure 5–5: CHARGING CURRENT COMPENSATION CONFIGURATIONS
POSITIVE & ZERO SEQUENCE CAPACITIVE REACTANCE:
The values of positive and zero sequence capacitive reactance of the protected line are required for charging current com-
pensation calculations. The line capacitive reactance values should be entered in primary kOhms for the total line length.
Details of the charging current compensation algorithm can be found in the THEORY OF OPERATION chapter.
If shunt reactors are also installed on the line, the resulting value entered in the POSITIVE and ZERO SEQUENCE
CAPACITIVE REACTANCE settings should be calculated as follows:
3-reactor arrangement: three identical line reactors ( X
1.
X
X
1line_capac
react
X
=
------------------------------------------------
C 1
X
X
react
1line_capac
4-reactor arrangement: three identical line reactors ( X
2.
nected between reactor-bank neutral and the ground.
X
X
1line_capac
react
X
=
------------------------------------------------
C 1
X
X
react
1line_capac
X
= the total line positive sequence capacitive reactance
1line_capac
X
= the total line zero sequence capacitive reactance
0line_capac
X
= the total reactor inductive reactance per phase. If reactors are installed at both ends of the line and are identi-
react
cal, the value of the inductive reactance is divided by 2 (or 3 for a 3-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
= the total neutral reactor inductive reactance. If reactors are installed at both ends of the line and are identi-
react_n
cal, the value of the inductive reactance is divided by 2 (or 3 for a 3-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:
GE Power Management
react
X
X
0line_capac
react
, X
=
------------------------------------------------
C 0
X
X
react
0line_capac
react
(
X
X
0line_capac
react
, X
=
-------------------------------------------------------------------------------- -
C 0
X
+ X
3
react
react_n
X
1
=
---------------------------------- -
react
X
react_terminal1
X
=
1
---------------------------------- -
react
X
react_terminal1
X
1
=
--------------------------------------- -
react
X
react_n_terminal1
L90 Line Differential Relay
) solidly connected phase to ground:
) wye-connected with the fourth reactor ( X
)
+ X
3
react_n
, where:
X
0line_capac
1
1
+
---------------------------------- -
X
react_terminal2
1
1
+
---------------------------------- -
+
---------------------------------- -
X
X
react_terminal2
react_terminal3
1
1
+
--------------------------------------- -
X
react_n_terminal2
5.3 SYSTEM SETUP
) con-
react_n
1
5-29
5

L90