CHAPTER 5: SETTINGS GROUPED ELEMENTSC70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL 5-2155NTRL CUR UNBALCE 1 K ANG — This setting defines angle of the factor compensating for the inherent unbalance of the bank.Under balanced conditions, the amount of the spill current measured in the neutral connection between the banks isproportional to the positive-sequence component of the total current of the two banks. This setting defines the angle ofthe proportionality factor. Quality of balancing the bank with a given value of this setting can be viewed under ACTUALVALUES menu. An automatic setting procedure is available under the COMMANDS menu to calculate the compensatingfactor automatically.NTRL CUR UNBALCE 1 STG1 PKP to NTRL CUR UNBALCE 1 STG4 PKP — These settings specify pickup thresholds for stages 1through 4 in per-units (pu) of the nominal current of the ground current channel of the bank source. A value of 1 pu is thenominal secondary current, or the nominal primary current, respectively, as configured under the bank source of thisfunction.NTRL CUR UNBALCE 1 STG1 SLOPE to NTRL CUR UNBALCE 1 STG4 SLOPE — These settings specify the slopes for stages 1 through4. The slope setting is applied if the phase CTs are configured under the bank source. The magnitude of the zero-sequencecurrent is applied as a restraining signal. Typically few percent of slope is enough to ensure security of the function. Thefactor compensating for the inherent bank unbalance zeroes out the operating signal under relatively balanced bankcurrents. If the said currents contain a significant zero sequence component, the quality of compensation is lower, hencethe need for the restraint, and this slope setting.NTRL CUR UNBALCE 1 STG1 DEL to NTRL CUR UNBALCE 1 STG4 DEL — This setting specifies the pickup time delay, individuallyper each stage of alarming/tripping. The timers use a common drop out time delay specified by the next setting.NTRL CUR UNBALCE 1 DPO DELAY — This setting controls a drop out delay for the operate FlexLogic operands. Individualstages apply individually configurable pickup delays, but use this common drop out delay.NTRL CUR 1 BLK STG1 to NTRL CUR 1 BLK STG4 — These settings are used to block the function on a per stage basis whenrequired. At minimum this function shall be blocked when the two banks are not paralleled. Note that when unblocked, thefunction becomes operational after five cycles of intentional delay. High-set instantaneous protection on energization canbe provided by a separate instantaneous overcurrent function.
