tPickUpRev: Sets the pick-up delay tPickUpRev to <80% of the breaker operate time, butwith a minimum of 20 ms.12.3.3.2 Weak-end infeed logicWEI: Set WEI to Echo, to activate the weak-end infeed function with only echo function.To activate echo with trip set WEI to Echo & Trip.tPickUpWEI: Set tPickUpWEI = 10 ms, a short delay is recommended to avoid thatspurious carrier received signals will activate WEI and cause unwanted signals.PU27PP and PU27PN: Set the voltage criterion PU27PP and PU27PN for the weak-endtrip to 70% of the system base voltage VBase. The setting should be below the minimumoperate voltage of the system but above the voltage that occurs for fault on the protectedline. The phase-to-phase elements must be verified to not operate for phase-to-groundfaults.12.4 Local acceleration logic ZCLCPLAL12.4.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberLocal acceleration logic ZCLCPLAL - -12.4.2 ApplicationThe local acceleration logic (ZCLCPLAL) is used in those applications whereconventional teleprotection scheme is not available (no communication channel), but theuser still require fast clearance for faults on the whole line.This logic enables fast fault clearing during certain conditions, but naturally, it can notfully replace a teleprotection scheme.The logic can be controlled either by the autorecloser (zone extension) or by the loss-of-load current (loss-of-load acceleration).The loss-of-load acceleration gives selected overreach zone permission to operateinstantaneously after check of the different current criteria. It can not operate for three-phase faults.1MRK 506 334-UUS A Section 12Scheme communication405Application manual
