• For an internal fault zone 2 in line end B will pick up and send a signal to line end A(CS).• If zone 4 (reverse) or none of the forward zones in line end A does not pick up thereceived signal from line end B (CR) will be sent back (echo).• If the voltage in line end A is low and the distance protection zones do not pick up thecircuit breaker is tripped (if this feature is set).• In line end B the echo signal is received (CR) and the communication scheme willgive an undelayed trip to the circuit breaker.The function at external fault can be described as:• For an external fault zone 2 in line end B will pick up and send a signal to line end A(CS).• Zone 4 (reverse) in line end A will pick up and prevent the received signal to be sentback to line end B.• None of the line ends will be tripped.1. Set WEI to Echo & TripEchoes the CR signal as well as, trip locally.2. Set tPickUpWEI to 0.01 sThe shortest duration of the CR signal.3. Set PU27PP to 70%Should be set lower than the lowest possible phase-to-phase voltage at non-faultedoperation. The setting is done in % of rated phase-to-phase voltage. Default settingis 70%.4. Set PU27PN to 70%Should be set lower than the lowest possible phase-to-ground voltage at non-faultedoperation. The setting is done in % of rated phase-to-ground voltage. Default settingis 70%.3.1.8 Calculating setting for switch into fault logic voltage and currentbased ZCVPSOFThe settings are made in primary values. These values are given in the base settings inGlobal base 1.1. Set GlobalBaseSel to 12. Set Mode to VILvl&Imp3. Set AutoInit to EnabledNo BC signal available4. Set IphPickup to 20 % of IBase1MRK 506 334-UUS A Section 3REL650 setting examples65Application manual
