does not provide any guidance in finding the faulted component. Therefore,ROV2PTOV (59N) is often used as a backup protection or as a release signal for thefeeder ground fault protection.10.3.3 Setting guidelines M13853-3 v8All the voltage conditions in the system where ROV2PTOV (59N) performs itsfunctions should be considered. The same also applies to the associated equipment, itsvoltage withstand capability and time characteristic.All voltage-related settings are made as a percentage of a settable base voltage, whichshall be set to the primary nominal voltage (phase-phase) level of the power system orthe high-voltage equipment under consideration.The time delay for ROV2PTOV (59N) is seldom critical, since residual voltage isrelated to ground faults in a high-impedance grounded system, and enough time mustnormally be given for the primary protection to clear the fault. In some more specificsituations, where the residual overvoltage protection is used to protect some specificequipment, the time delay is shorter.Some applications and related setting guidelines for the residual voltage level are givenbelow.10.3.3.1 Equipment protection, such as for motors, generators, reactors andtransformersEquipment protection for transformers M13853-9 v8High residual voltage indicates ground fault in the system, perhaps in the component towhich two step residual overvoltage protection (ROV2PTOV, 59N) is connected. Forselectivity reasons to the primary protection for the faulted device, ROV2PTOV (59N)must trip the component with some time delay. The setting must be above the highestoccurring "normal" residual voltage and below the highest acceptable residual voltagefor the equipment.10.3.3.2 Equipment protection, capacitors M13853-12 v4High voltage will deteriorate the dielectric and the insulation. Two step residualovervoltage protection (ROV2PTOV, 59N) has to be connected to a neutral or opendelta winding. The setting must be above the highest occurring "normal" residualvoltage and below the highest acceptable residual voltage for the capacitor.Section 10 1MRK 504 163-UUS AVoltage protection622 Transformer protection RET670 2.2 ANSIApplication manual
