11.2.3.5 Delta U and delta I GUID-02336F26-98C0-419D-8759-45F5F12580DE v7Set the operation mode selectorOpDUDI toOn if the delta function shall be in operation.The setting ofDU> should be set high (approximately 60% ofUBase) and the current thresholdDI< low (approximately 10% ofIBase) to avoid unwanted operation due to normal switchingconditions in the network. The delta current and delta voltage function shall always be usedtogether with either the negative or zero sequence algorithm. IfUSetprim is the primary voltagefor operation of dU/dt andISetprim the primary current for operation of dI/dt, the setting ofDU> andDI< will be given according to equation 159 and equation 160.DU USetUBaseprim> = 100.EQUATION1523 V3 EN-US (Equation 159)DI ISetIBaseprim< = 100.EQUATION1524 V4 EN-US (Equation 160)The voltage thresholdsUPh> is used to identify low voltage condition in the system. SetUPh>below the minimum operating voltage that might occur during emergency conditions. Asetting of approximately 70% ofUBase is recommended.The current thresholdIPh> shall be set lower than theIMinOp for the distance protectionfunction. A 5...10% lower value is recommended.11.2.3.6 Dead line detection M13683-78 v4The condition for operation of the dead line detection is set by the parametersIDLD< for thecurrent threshold andUDLD< for the voltage threshold.Set theIDLD< with a sufficient margin below the minimum expected load current. A safetymargin of at least 15-20% is recommended. The operate value must however exceed themaximum charging current of an overhead line, when only one phase is disconnected (mutualcoupling to the other phases).Set theUDLD< with a sufficient margin below the minimum expected operating voltage. Asafety margin of at least 15% is recommended.1MRK 505 363-UEN A Section 11Secondary system supervision203Application manual
