If the denominator in equation 253 is called B and Z0m is simplified to X0m, thenthe real and imaginary part of the reach reduction factor for the overreaching zonescan be written as:( ) ( )( ) ( )2 20 ReRe 0 1 Re ImX m BK B B×= - +EQUATION1427 V2 EN-US (Equation 254)( ) ( )( ) ( )2 20 ImIm 0 Re ImX m BK B B×= +EQUATION1428 V2 EN-US (Equation 255)Parallel line is out of service and earthed in both endsGUID-AEF4E5D3-A486-4DC7-8B95-83AADE67F966 v1Apply the same measures as in the case with a single set of setting parameters. Thismeans that an underreaching zone must not overreach the end of a protected circuitfor the single phase-to-earth faults.Set the values of the corresponding zone (zero-sequence resistance and reactance)equal to:R0E R0 1 Xm02R02 X02+--------------------------+è øç ÷æ ö×=EQUATION561 V1 EN-US (Equation 256)X0E X0 1 Xm02R02 X02+--------------------------–è øç ÷æ ö×=EQUATION562 V1 EN-US (Equation 257)8.9.3.6 Setting of reach in resistive direction GUID-3BFE80FD-8A51-4B71-8762-73DFA73AB28B v2Set the resistive independently for each zone.Set separately the expected fault resistance for phase-to-phase faults RFPP and forthe phase-to-earth faults RFPE for each zone. For each distance zone, set allremaining reach setting parameters independently of each other.The final reach in resistive direction for phase-to-earth fault loop measurementautomatically follows the values of the line-positive and zero-sequence resistance,and at the end of the protected zone is equal to equation 258. 1R 2 R1Zx R0Zx RFPEZx3 IECEQUATION2303 V2 EN-US (Equation 258)1MRK 506 369-UEN B Section 8Impedance protectionLine distance protection REL670 2.2 IEC 309Application manual
