9-12 L30 Line Current Differential System GE Multilin9.4 INSTANTANEOUS ELEMENTS 9 APPLICATION OF SETTINGS9Figure 9–5: MAXIMUM ERROR FOR 50 HZ SYSTEMTo secure instantaneous element operation, it is recommended to use either FlexLogic as shown next to block the instanta-neous elements during synchronization, or to use a different setting group with more conservative pickup for this brief inter-val. A 700 ms drop-off timer in the logic is shown as an example to guarantee error below 3 percent, but delay can berealistically even shorter, if the setting security margin allows this.Figure 9–6: FLEXLOGIC TO BLOCK INSTANTANEOUS ELEMENT DURING 87L STARTUP831792A2.CDRAND(2)OR(2)87L DIFF PFLL FAIL87L DIFF CH1 FAIL87L DIFF CH2 FAILOR(2)NEGATIVE ONE SHOTTIMER 2AND(2)TIMER 1= BLOCK INST (VO5)0 ms50 ms= BLOCK INST (VO5)0 ms700 ms
