See the preprocessing function blocks in this document for thepossible signal sources.Improper analog channel configuration causes a validation error if the analogchannels are not completely configured or they do not match with certain settings. Fortroubleshooting, check the contents of this chapter and also the preprocessing blocksin this document. The configuration can be written to the protection relay once themismatch is corrected.4.12.3.5 Operation principleThe function can be enabled and disabled with the Operation setting. Thecorresponding parameter values are “On” and “Off”.The three-phase current unbalance protection for shunt capacitor banks operates onthe DFT measurement mode. The operation of HCUBPTOC can be described byusing a module diagram. All the modules in the diagram are explained in the nextsections.BLOCKOPERATENaturalunbalancecompens-ationSTARTALARMLeveldetector 1Leveldetector 2BlockinglogicTimer 2tI3P2I3P1 I_AI_UNB_AI_UNB_BI_UNB_C tTimer 1tGUID-9FDAE00A-E297-426D-96D1-B1E78DC4B16C V1 ENFigure 557: Function module diagramNatural unbalance compensationIn the three-phase H-bridge-connected shunt capacitor bank configuration, theunbalance currents I_UNB_A, I_UNB_B and I_UNB_C are measured at thecommon points of the H-bridge.Section 4 1MRS759142 CProtection functions1034 REX640Technical Manual
