In many cases, UV2PTUV is a useful function in circuits for local or remoteautomation processes in the power system.8.1.3 Setting guidelines M13851-3 v9All the voltage conditions in the system where UV2PTUV performs its functionsshould be considered. The same also applies to the associated equipment, itsvoltage and time characteristic.There is a very wide application area where general undervoltage functions areused. All voltage-related settings are made as a percentage of the global base valueUBase, which normally is set to the primary rated voltage level (phase-to-phase) ofthe power system or the high voltage equipment under consideration.The trip time setting for UV2PTUV is normally not critical, since there must beenough time available for the main protection to clear short circuits and earthfaults.Some applications and related setting guidelines for the voltage level are describedin the following sections.8.1.3.1 Equipment protection, such as for motors and generators M13851-50 v3The setting must be below the lowest occurring "normal" voltage and above thelowest acceptable voltage for the equipment.8.1.3.2 Disconnected equipment detection M13851-53 v3The setting must be below the lowest occurring "normal" voltage and above thehighest occurring voltage, caused by inductive or capacitive coupling, when theequipment is disconnected.8.1.3.3 Power supply quality M13851-56 v3The setting must be below the lowest occurring "normal" voltage and above thelowest acceptable voltage, due to regulation, good practice or other agreements.8.1.3.4 Voltage instability mitigation M13851-59 v3This setting is very much dependent on the power system characteristics, andthorough studies have to be made to find the suitable levels.8.1.3.5 Backup protection for power system faults M13851-62 v3The setting must be below the lowest occurring "normal" voltage and above thehighest occurring voltage during the fault conditions under consideration.Section 8 1MRK 504 169-UEN AVoltage protection144 Transformer protection RET650 2.2 IECApplication manual
