Section 8 Voltage protection8.1 Loss of voltage check LOVPTUV SEMOD171868-1 v28.1.1 IdentificationSEMOD171954-2 v2Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberLoss of voltage check LOVPTUV - 278.1.2 Application SEMOD171876-4 v3The trip of the circuit breaker at a prolonged loss of voltage at all the three phases is normallyused in automatic restoration systems to facilitate the system restoration after a majorblackout. Loss of voltage check (LOVPTUV) generates a TRIP signal only if the voltage in all thethree phases is low for more than the set time. If the trip to the circuit breaker is not required,LOVPTUV is used for signallization only through an output contact or through the eventrecording function.8.1.3 Setting guidelines SEMOD171929-4 v5Loss of voltage check (LOVPTUV) is in principle independent of the protection functions. Itrequires to be set to open the circuit breaker in order to allow a simple system restorationfollowing a main voltage loss of a big part of the network and only when the voltage is lostwith breakers still closed.All settings are in primary values or per unit. Set operate level per phase to typically 70% of theglobal parameterUBase level. Set the time delaytTrip=5-20 seconds.8.1.3.1 Advanced users settings SEMOD171929-8 v4For advanced users the following parameters need also to be set. Set the length of the trippulse to typicaltPulse=0.15 sec. Set the blocking timetBlock to block Loss of voltage check(LOVPTUV), if some but not all voltage are low, to typical 5.0 seconds and set the time delayfor enabling the function after restorationtRestore to 3 - 40 seconds.1MRK 504 158-UEN A Section 8Voltage protection137Application manual
