GE C70 Instruction Manual page 423

7 COMMANDS AND TARGETS
e) NEUTRAL CURRENT UNBALANCE

PATH: COMMANDS CAPACITOR BANK AUTO...
 NEUTRAL CURRENT
 UNBALANCE 1
MESSAGE
MESSAGE
The auto-setting feature shall be used when the capacitor bank is online and the 60N function is enabled. For security rea-
sons, it may be necessary to apply less sensitive settings during the auto-setting process. Temporarily switching to an alter-
nate setting group with less sensitive pickup thresholds is a method of providing for this extra security.
The feature can be used with manual acceptance of the auto-calculated coefficients (the
command switched to "Manual"), or with automatic acceptance of the calculated factors (the
command switched to "Auto").
SET
The feature is used as follows.
Application with Manual Supervision of the Automatically Calculated Factors
When the
NTRL CUR UNBALACE 1 AUTO-SET
and one for angle of the compensating factor) display the values that best balance the function and prompt for permission
to apply the calculated value as a new setting. When confirmed, the auto-selected value is applied to all setting groups.
After user consent to apply the calculated coefficient is received, the
for the duration of the flash message time. The timeout period is intended for field staff to make a note of the newly applied
coefficient. However, it is possible to immediately navigate from this screen. The new setting values can be viewed in the
menu at any time.
SETTING
After the process if finished, it is recommended to disable the auto-setting feature. If not disabled by the user, the feature is
automatically disabled when user-initiated front panel interface activity ceases and the C70 display is dimmed.
Certain security conditions are checked during the auto-setting process. If these conditions are violated, the
message is displayed in the second line.
If the neutral voltage unbalance function is disabled or blocked, the auto-setting process is not functional and the
message is displayed in the second line.
RUNNING
Application with Automatic Supervision of the Automatically Calculated Factors
When the
NTRL CUR UNBALACE 1 AUTO-SET
ancing coefficients is fully automatic. Typical applications require setting this function to "Auto" with the bank de-energized,
then subsequently energizing the capacitor bank. After the function is set to "Auto", it expects to read valid input signals as
a result of bank energization within the display flash message time duration to calculate and apply factors. Otherwise, the
function is switched backed to "Disabled". When the bank is energized and the five-cycle timer of the 60N function expires,
the balancing coefficients are calculated and automatically applied. After the new balancing factors are applied, the auto-
setting function switches automatically from "Auto" to "Disabled", and the 60N element becomes operational. In essence,
the when in the "Auto" mode, the confirmation command is automatically executed immediately after the balancing values
become available. The C70 does not display the applied coefficients in the "Auto" mode; instead, they may be viewed in the
menu.
SETTINGS
If the supervisory conditions are not satisfied in the "Auto" mode within time defined by the
ting, the message is displayed and the 60N function starts running with the pre-existing settings for the balanc-
AUTO FAIL
ing factors.
GE Multilin

NEUTRAL CURRENT UNBALANCE
NTRL CUR UNBALACE 1
AUTO-SET: Disabled
NTRL CUR 1 k=0.0000
APPLY MAGNITUDE? No
NTRL CUR 1 k=0°
APPLY ANGLE? No
command is switched to "Manual", the auto-setting screens (one for magnitude
command is switched to "Auto", the process of calculating and applying the bal-
C70 Capacitor Bank Protection and Control System

NEUTRAL CURRENT UNBALANCE 1(3)
Range: Disabled, Manual, Auto
Range: Yes, No
Range: Yes, No
NTRL CUR UNBALACE 1 AUTO-SET
NTRL CUR UNBALACE 1 AUTO-
confirmation message is displayed
k =?.???? APPLIED
DEFAULT MESSAGE TIMEOUT
7.1 COMMANDS
SUPV FAIL
60N NOT
7
set-
7-5