Section 8 Voltage protection8.1 Two step undervoltage protection UV2PTUV (27)8.1.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberTwo step undervoltage protection UV2PTUV3U<SYMBOL-R-2U-GREATER-THANV2 EN278.1.2 ApplicationTwo-step undervoltage protection function (UV2PTUV ,27) is applicable in all situations,where reliable detection of low phase voltages is necessary. It is used also as a supervisionand fault detection function for other protection functions, to increase the security of acomplete protection system.UV2PTUV (27) is applied to power system elements, such as generators, transformers,motors and power lines in order to detect low voltage conditions. Low voltage conditionsare caused by abnormal operation or fault in the power system. UV2PTUV (27) is used incombination with overcurrent protections, either as restraint or in logic "and gates" of thetrip signals issued by the two functions. Other applications are the detection of "novoltage" condition, for example, before the energization of a HV line or for automaticbreaker trip in case of a blackout. UV2PTUV (27) is also used to initiate voltage correctionmeasures, like insertion of shunt capacitor banks to compensate for reactive load andthereby increasing the voltage. The function has a high measuring accuracy to allowapplications to control reactive load.UV2PTUV (27) is used to disconnect apparatuses, like electric motors, which will bedamaged when subject to service under low voltage conditions. UV2PTUV (27) dealswith low voltage conditions at power system frequency, which can be caused by thefollowing reasons:1MRK 506 334-UUS A Section 8Voltage protection255Application manual
