Section 8 Multipurpose protection8.1 General current and voltage protection CVGAPC IP14552-1 v28.1.1 IdentificationM14886-2 v3Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberGeneral current and voltageprotectionCVGAPC 2(I>/U<) -8.1.2 Application IP15008-1 v1M13084-3 v4A breakdown of the insulation between phase conductors or a phase conductor and earthresults in a short circuit or an earth fault respectively. Such faults can result in large faultcurrents and may cause severe damage to the power system primary equipment. Dependingon the magnitude and type of the fault different overcurrent protections, based onmeasurement of phase, earth or sequence current components can be used to clear thesefaults. Additionally it is sometimes required that these overcurrent protections shall bedirectional and/or voltage controlled/restrained.The over/under voltage protection is applied on power system elements, such as generators,transformers, motors and power lines in order to detect abnormal voltage conditions.Depending on the type of voltage deviation and type of power system abnormal conditiondifferent over/under voltage protections based on measurement of phase-to-earth, phase-to-phase, residual- or sequence- voltage components can be used to detect and operate for suchincident.The IED can be provided with multiple General current and voltage protection (CVGAPC)protection modules. The function is always connected to three-phase current and three-phasevoltage input in the configuration tool, but it will always measure only one current and onevoltage quantity selected by the end user in the setting tool.Each CVGAPC function module has got four independent protection elements built into it.1. Two overcurrent steps with the following built-in features:• Definite time delay or Inverse Time Overcurrent TOC/IDMT delay for both steps• Second harmonic supervision is available in order to only allow operation of theovercurrent stage(s) if the content of the second harmonic in the measured currentis lower than pre-set level• Directional supervision is available in order to only allow operation of theovercurrent stage(s) if the fault location is in the pre-set direction (Forward orReverse). Its behavior during low-level polarizing voltage is settable (Non-Directional,Block,Memory)• Voltage restrained/controlled feature is available in order to modify the pick-up levelof the overcurrent stage(s) in proportion to the magnitude of the measured voltage• Current restrained feature is available in order to only allow operation of theovercurrent stage(s) if the measured current quantity is bigger than the setpercentage of the current restrain quantity.2. Two undercurrent steps with the following built-in features:1MRK 505 355-UEN A Section 8Multipurpose protection129Application manual
