Characteristic ValueOperate time accuracy in definite time mode ±1.0% of the set value or ±20 msOperate time accuracy in IDMT mode 3) ±5.0% of the set value or ±20 msSuppression of harmonics -50 dB at f = fn-3 dB at f = 13 × fn1) Fundamental frequency current = 1.0 × In, harmonics current before fault = 0.0 × In, harmonics faultcurrent 2.0 ×Start value, results based on statistical distribution of 1000 measurements2) Includes the delay of the signal output contact3) MaximumStart value = 2.5 × In,Start value multiples in range of 2...204.2.6 Wattmetric-based earth-fault protection WPWDE4.2.6.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberWattmetric-based earth-fault protection WPWDE Po> -> 32N4.2.6.2 Function blockGUID-EDE21448-13FD-44E3-AF7C-CFD47A5C99DC V1 ENFigure 187: Function block4.2.6.3 FunctionalityThe wattmetric-based earth-fault protection function WPWDE can be used to detectearth faults in unearthed networks, compensated networks (Petersen coil-earthednetworks) or networks with a high-impedance earthing. It can be used as an alternativesolution to the traditional residual current-based earth-fault protection functions, forexample, the IoCos mode in the directional earth-fault protection functionDEFxPDEF.WPWDE measures the earth-fault power 3UoIoCosφ and gives an operating signalwhen the residual current Io, residual voltage Uo and the earth-fault power exceed theset limits and the angle (φ) between the residual current and the residual voltage isinside the set operating sector, that is, forward or backward sector. The operating timecharacteristic can be selected to be either definite time (DT) or a special wattmetric-type inverse definite minimum type (wattmetric type IDMT).The wattmetric-based earth-fault protection is very sensitive to current transformererrors and it is recommended that a core balance CT is used for measuring the residualcurrent.Section 4 1MRS758755 AProtection functions360 REC615 and RER615Technical Manual
