GE C70 Instruction Manual page 426

COMMANDS MENU
If the neutral voltage unbalance function is disabled or blocked, the auto-setting process is not functional and the 59NU
NOT RUNNING message displays in the second line.
Automatic supervision of automatically calculated factors
When the
NTRL VOL UNBAL 1 AUTO SET
balancing coefficients is fully automatic. Typical applications require setting this function to "Auto" with the bank de-
energized, then 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 returned to "Disabled." When the bank is energized and the five-cycle timer of the 59NU function expires, the
balancing coefficients are calculated and automatically applied. When the new balancing factors are applied, the function
switches automatically from "Auto" to "Disabled" and the 59NU function becomes operational. In essence, when in the
"Auto" mode, the confirmation command executes automatically immediately after the balancing values are available.
The C70 does not display the applied coefficients in the "Auto" mode; rather, they are be viewed in the
When the supervisory conditions are not satisfied in "Auto" mode, the AUTO FAIL message displays and the 59NU function
starts running with the pre-existing settings for the balancing factors.
7.1.1.4 Phase current unbalance
COMMANDS  CAPACITOR BANK AUTO SETTING  PHASE CURRENT UNBALANCE  PHASE CURRENT UNBALANCE 1(3)
 PHASE CURRENT
 UNBALANCE 1
Use the auto-setting feature when the capacitor bank is online and the 60P function is enabled. For security reasons, apply
less sensitive settings during the auto-setting process. Switching temporarily to an alternate setting group with less
sensitive pickup thresholds is a method to provide the extra security.
The feature can be used with by manual accepting the auto-calculated coefficients (the
command switched to "Manual") or by automatic acceptance of the calculated factors (the
command switched to "Auto").
7
The feature is used as follows.
Application with manual supervision of the automatically calculated factors
When the
CUR UNBALACE 1 AUTO SETTINGS
display values that best balance the function in a given phase 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 having same source as active
group during the auto-setting procedure. The balancing factors can be either positive or negative, depending on which of
the two banks has a lower impedance, and on the polarity of the differential CTs connected to the relay.
After user consent to apply the calculated coefficient is received, the "k =?.???? APPLIED" confirmation message displays
for the duration of the flash message time. The timeout period allows field staff to make 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.
SETTINGS
After the process finishes, it is recommended to disable the auto-setting feature. If not disabled, the feature automatically
disables itself when user-initiated front panel interface activity ceases and the C70 display is dimmed.
Certain security conditions are checked during the auto-setting process, such as frequency deviation from the nominal
and the magnitude of the phase currents above 0.1 pu. If any of these conditions are violated, the SUPV FAIL message
displays in the second line.
7-4
command is switched to "Auto", the process of calculating and applying the
CUR UNBALACE 1 AUTO

SETTINGS: Disabled
CUR UNB 1A k=0.0000

APPLY IN PHS A? No
CUR UNB 1A k=0.0000

APPLY IN PHS B? No
CUR UNB 1A k=0.0000

APPLY IN PHS C? No
command is switched to "Manual," the auto-setting screens (one for each phase)
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: COMMANDS AND TARGETS
SETTINGS
Range: Disabled, Manual, Auto
Range: Yes, No
Range: Yes, No
Range: Yes, No
CUR UNBALACE 1 AUTO SETTINGS
CUR UNBALACE 1 AUTO SETTINGS
menu.