7.2.1 IdentificationM17002-1 v7Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberTwo step overvoltage protection OV2PTOV3U>SYMBOL-C-2U-SMALLER-THAN V2 EN-US597.2.2 Application M13799-3 v8Two step overvoltage protection OV2PTOV is applicable in all situations, where reliabledetection of high voltage is necessary. OV2PTOV is used for supervision and detection ofabnormal conditions, which, in combination with other protection functions, increase thesecurity of a complete protection system.High overvoltage conditions are caused by abnormal situations in the power system. OV2PTOVis applied to power system elements, such as generators, transformers, motors and powerlines in order to detect high voltage conditions. OV2PTOV is used in combination with lowcurrent signals, to identify a transmission line, open in the remote end. In addition to that,OV2PTOV is also used to initiate voltage correction measures, like insertion of shunt reactors,to compensate for low load, and thereby decreasing the voltage. The function has a highmeasuring accuracy and hysteresis setting to allow applications to control reactive load.OV2PTOV is used to disconnect apparatuses, like electric motors, which will be damaged whensubject to service under high voltage conditions. It deals with high voltage conditions atpower system frequency, which can be caused by:1. Different kinds of faults, where a too high voltage appears in a certain power system, likemetallic connection to a higher voltage level (broken conductor falling down to a crossingoverhead line, transformer flash over fault from the high voltage winding to the lowvoltage winding and so on).2. Malfunctioning of a voltage regulator or wrong settings under manual control(symmetrical voltage decrease).3. Low load compared to the reactive power generation (symmetrical voltage decrease).4. Earth-faults in high impedance earthed systems causes, beside the high voltage in theneutral, high voltages in the two non-faulted phases, (unsymmetrical voltage increase).OV2PTOV prevents sensitive equipment from running under conditions that could cause theiroverheating or stress of insulation material, and, thus, shorten their life time expectancy. Inmany cases, it is a useful function in circuits for local or remote automation processes in thepower system.7.2.3 Setting guidelines M13852-4 v9The parameters for Two step overvoltage protection (OV2PTOV) are set via the local HMI orPCM600.All the voltage conditions in the system where OV2PTOV performs its functions should beconsidered. The same also applies to the associated equipment, its voltage and timecharacteristic.There is a very wide application area where general overvoltage functions are used. All voltagerelated settings are made as a percentage of a settable base primary voltage, which normallySection 7 1MRK 505 355-UEN AVoltage protection120Application manual
