5-164 L60 Line Phase Comparison System GE Multilin5.5 GROUPED ELEMENTS 5 SETTINGS5Figure 5–76: GROUND DISTANCE ZONES 2 AND HIGHER SCHEME LOGICGROUND DIRECTIONAL SUPERVISION:A dual (zero-sequence and negative-sequence) memory-polarized directional supervision applied to the ground distanceprotection elements has been shown to give good directional integrity. However, a reverse double-line-to-ground fault canlead to a maloperation of the ground element in a sound phase if the zone reach setting is increased to cover high resis-tance faults.Ground distance zones 2 and higher use an additional ground directional supervision to enhance directional integrity. Theelement’s directional characteristic angle is used as a maximum torque angle together with a 90° limit angle.The supervision is biased toward operation in order to avoid compromising the sensitivity of ground distance elements atlow signal levels. Otherwise, the reverse fault condition that generates concern will have high polarizing levels so that a cor-rect reverse fault decision can be reliably made.The supervision for zones 2 and 3 is removed during open pole conditions.$.&'5$1'$1'$1'254XDGULODWHUDOFKDUDFWHULVWLFRQO\$1'250(025<9B!SX,B!SX6(77,1*(QDEOHG 'LVDEOHG *1'',67=)81&7,216(77,1*2II *1'',67=%/.6(77,1*,$,%',67$1&(6285&(,&9$*9%*9&*9B,B:\H97V6(77,1*6*1'',67==20=$1*581$(/(0(17581%(/(0(17581&(/(0(17*1'',67=32/&855(17*1'',67=121+20*(1$1**1'',67=&203/,0,7*1'',67=',55&$*1'',67 ',5&203/,0,7=*1'',67=92/7/(9(/*1'',67=48$'5*7%/'*1'',67=48$'5*7%/'5&$*1'',67=48$'/)7%/'*1'',67=48$'/)7%/'5&$7,0(5F\FOHF\FOH6(77,1**1'',67=6839581_,1²î,B_!3LFNXS)/(;/2*,&23(5$1'6*1'',67=3.3$*1'',67='32$)/(;/2*,&23(5$1'6*1' =',67 3.3%*1'',67='32%)/(;/2*,&23(5$1'6*1' =',67 3.3&*1'',67='32&)/(;/2*,&23(5$1'*1' =',67 3.3)/(;/2*,&23(5$1'623(132/(23 $ƹ23(132/(23 %ƹ23(132/(23 &ƹ'/DQG/ RQO\*1'',67=6831,1*1'',67=',56831)/(;/2*,&23(5$1'23(132/(23,1,B,B*1'',67=5(95($&+*1'',67=5(95($&+5&$*1'',67=5($&+*1'',67=5&$*1'',67==20=0$**1'',67===$1**1'',67===0$**1'',67=6+$3(*1'',67=',525'/DQG/ RQO\
