GE L60 Instruction Manual page 266

Line phase comparison system, ur series
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5.5 GROUPED ELEMENTS
i) CHARGE CURRENT COMPENSATION

PATH: SETTINGS
GROUPED ELEMENTS
 CHARGE CURRENT
 COMPENSATION
CHARGING CURRENT COMPENSATN: This setting enables and disables the charging current calculations and cor-
rections of the mixed current used as an operating quantity for fault detectors and square pulses. The voltage signals
used for charging current compensation are taken from source 3 or 4 assigned with the three-phase voltage bank on
the L5 voltage bank. As such, it is critical to ensure that three-phase line voltage is assigned to this source and voltage
bank settings are entered correctly. Half (or one-third for the three-terminal line, as defined by the
setting) of the line charging current is subtracted from the line current.
SELECT
This setting is forced to "Disabled" if a phase VT bank is not assigned at either source 3 or source 4.
The following diagram shows possible configurations.
A B C
5
Figure 5–52: CHARGING CURRENT COMPENSATION CONFIGURATIONS
CHARGE COMPENST BLOCK: This setting selects an input to block charging current compensation. This input is
typically the VT fuse fail element of the source, where the three-phase VT is configured with this setting to block com-
pensation. Blocking charging current compensation at one end of the line does not block charging current compensa-
tion on the other end. However, even with compensation operating at one end ½ (or 1/3) of the charging current is still
removed from the net phase comparison current. Alternatively, the customer may choose to switch to another setting
group with more conservative phase comparison settings during a VT fuse fail condition.
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 kilo-ohms for the total line length. Details of the charging current compen-
sation 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
ZERO SEQ CAPACITIVE REACTANCE
1.
No shunt reactors on the line or reactor current is subtracted from the line current, forcing the L60 to measure the
uncompensated by shunt reactors load/fault current plus the full charging current.
5-128
PHASE COMPARISON ELEMENTS
CHARGE CURRENT
COMPENSATN: Disabled
CHARGE COMPENST BLK:
MESSAGE
Off
POS SEQ CAPACITIVE
MESSAGE
REACTANCE: 0.100 KΩ
ZERO SEQ CAPACITIVE
MESSAGE
REACTANCE: 0.100 KΩ
Possible 3-Reactor
arrangement
Line Capacitive Reactance
Xreact
X1line_capac
X0line_capac
settings should be calculated as follows:
X
X
=
C1
1line_capac
L60 Line Phase Comparison System

CHARGE CURRENT COMPENSATION
Range: Disabled, Enabled
Range: any FlexLogic™ operand
Range: 0.100 to 65.535 kohms in steps of 0.001
Range: 0.100 to 65.535 kohms in steps of 0.001
Possible 4-Reactor
arrangement
Xreact_n
POS SEQ CAPACITIVE REACTANCE
, X
X
=
C0
0line_capac
5 SETTINGS
87PC SCHEME
A B C
Xreact
831731A3.CDR
and
(EQ 5.7)
GE Multilin

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