UV2PTUV can be set to measure phase-to-earth fundamental value, phase-to-phasefundamental value, phase-to-earth true RMS value or phase-to-phase true RMS value.The choice of the measuring is done by the parameter ConnType. The voltage relatedsettings are made in percent of base voltage which is set in kV phase-to-phase voltage.This means operation for phase-to-earth voltage under:U UBase kV< ⋅(%) ( )3EQUATION1429 V2 EN (Equation 104)and operation for phase-to-phase voltage under:U (%) UBase(kV)< ×EQUATION1990 V1 EN (Equation 105)When phase-to-earth voltage measurement is selected the functionautomatically introduces division of the base value by the square rootof three.9.1.7.1 Measurement principleDepending on the set ConnType value, UV2PTUV measures phase-to-earth or phase-to-phase voltages and compare against set values, U1< and U2<. The parametersOpMode1 and OpMode2 influence the requirements to activate the START outputs.Either 1 out of 3, 2 out of 3, or 3 out of 3 measured voltages have to be lower than thecorresponding set point to issue the corresponding START signal.To avoid oscillations of the output START signal, a hysteresis has been included.9.1.7.2 Time delayThe time delay for the two steps can be either definite time delay (DT) or inverse timedelay (IDMT). For the inverse time delay three different modes are available:• inverse curve A• inverse curve B• customer programmable inverse curveThe type A curve is described as:nnkt U UU= æ ö< -ç ÷<è øEQUATION1431 V2 EN (Equation 106)Section 9 1MRK502052-UEN BVoltage protection482Technical manual
