GE UR Series C70, Instruction Manual

Page: 303 / 614

GE Multilin C70 Capacitor Bank Protection and Control System 5-179
5 SETTINGS 5.7 CONTROL ELEMENTS
5
Figure 5–89: AUTOMATIC VOLTAGE REGULATOR PICKUP CHARACTERISTICS IN “VAR” MODE
Care should be taken that the settings do not result in the capacitor being continuously cycled close and open. In the volt-
age mode the close voltage settings should be lower than the open voltage setting by more than the voltage change
expected from capacitor switching, plus margin. Similarly in the “VAR” mode the close var setting should be higher than the
open var setting by more than the expected var change due to capacitor switching, plus margin. For configurations where
the capacitor current is not included in the measured current, there could still be a measured var change due to loads
whose power factor increases with increasing voltage. In general, the larger the margin, the less often the capacitor will be
switched.
Delays should be set long enough to avoid undesired operations on transient conditions. Depending on the application, this
could include operations for noise hits, for transient voltage depressions accompanying successful fault clearance, and
short-term voltage conditions pending automatic reclosure. Delays can also be used to time co-ordinate the switching of
multiple capacitor banks, or sections of the same bank.
The following settings are available.
• AVR 1 SOURCE : Selects signal source of the control variables of interest. In case of voltage control applications, the
selected source needs to have the appropriate voltages configured for proper operation. For example, when using pos-
itive-sequence voltage as a control variable, phase voltages must be configured under the source; or when using sin-
gle-phase auxiliary voltage, the auxiliary source voltage must be configured. In case of “VAR” mode and of voltage
mode with voltage drop compensation, the indicated source must be configured with phase voltages and currents into
the regulated load or bus, and should include the capacitor current. If the source indicated here does not support the
control variable selected, the function will restrain itself from operating, and assert neither the close or open command.
• AVR 1 MINIMUM VOLTAGE : This value sets the minimum voltage for capacitor switching, to discriminate against loss
of voltage. For voltage mode, this setting applies to the voltage selected for control. For “VAR” mode, this setting
applies to the positive sequence voltage.
• AVR 1 CONTROL MODE : This setting selects either voltage control for voltage regulation applications, or var control
for power factor/reactive power regulation applications.
• AVR 1 VOLT OPERATING SIGNAL : When the control mode is voltage, this setting is used to select whether the AVR
responds to an individual phase-to-phase voltage or phase-to-ground voltage, the average of the three phase-to-phase
voltages, the positive sequence voltage, or the auxiliary RMS voltage. The ability to select the same voltage quantity
as is used by other AVRs facilitates coordination with those AVRs.
• AVR 1 VOLT LEVEL TO CLOSE : In the voltage mode, this setting specifies the voltage level at or below which to
issue the close command.
834732A1.CDR
Q
P
PO
WE
R FA
CTO
R LIMI
T
CLOSE PKP
OPEN PKP
0
VAR OPEN MODE: Minimize No. of Ops.
VAR LEVEL
TO CLOSE
VAR LEVEL
TO OPEN
Q
P
POWER
FACT
OR
LIMIT
CLOSE PKP
0
OPEN PKP
VAR OPEN MODE: Minimize Uptime
minimum expected kW demand minimum expected kW demand
POWER
FACT
OR
LIMIT
VAR LEVEL
TO CLOSE
VAR LEVEL
TO OPEN