Section 8 Voltage protection8.1 Two step undervoltage protection UV2PTUV IP14544-1 v38.1.1 IdentificationM16876-1 v7Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberTwo step undervoltage protection UV2PTUV3U<SYMBOL-R-2U-GREATER-THANV2 EN-US278.1.2 Application M13790-3 v8Two-step undervoltage protection function (UV2PTUV) is applied to power systemelements, such as generators, transformers, motors and power lines in order todetect low voltage conditions. It is used as a supervision and fault detectionfunction for other protection functions as well, to increase the security of acomplete protection system. Low voltage conditions are caused by abnormaloperation or faults in the power system, such as:• Malfunctioning of a voltage regulator or wrong settings under manual control(symmetrical voltage decrease)• Overload (symmetrical voltage decrease)• Short circuits, often as phase-to-earth faults (unsymmetrical voltage decrease)UV2PTUV is used in combination with overcurrent protections, either as restraintor in logic "and gates" of the trip signals issued by the two functions. It can also beused to:• Detect no voltage conditions, for example, before the energization of a HV lineor for automatic breaker trip in case of a blackout• Initiate voltage correction measures, like insertion of shunt capacitor banks tocompensate for reactive load and thereby increasing the voltage• Disconnect apparatuses, like electric motors, which will be damaged whensubject to service under low voltage conditions.The function has a high measuring accuracy and a settable hysteresis to allowapplications to control reactive load.1MRK 504 169-UEN A Section 8Voltage protectionTransformer protection RET650 2.2 IEC 143Application manual
