these conditions is primarily a function of I2R copper losses. Because temperatureincreases with current, it is logical to apply overcurrent elements with inverse time-current characteristics. The generator overcurrent applications are complicated by thecomplexity of generator thermal characteristics and the time-varying nature of currentexperienced during starting and when the generator drives a time-varying load.The generator rotor overload function GRPTTR protects rotor windings againstexcessive temperature rise as result of overcurrents.9.16.3 Setting guidelineTwo setting examples will be given for two applications as shown in Figure 204.100MVA380/18kVYNd5G100MVA18kV3210A500kVA18/0,4kVDy5100/11000/5Field rating:810A, 260V DC320MVA242/11kVYNd5G315MVA11kV16533A1400kVA11/0,55kVYd11100/51500/5Field rating:1520A, 295V DCa) b)IEC12000182-1-en.vsdIEC12000182 V1 ENFigure 204: Two application examplesFirst example (shown in a) is for a 100MVA machine and the second example (shownin b) is for a 315MVA machine.It is important to know which CT (that is, on HV or LV side of the excitationtransformer) is used. Make sure that appropriate CT ratio (for example, 100/1 or1000/5) is set on these three analogue inputs.All settings will be given in a table format for both applications.1MRK 502 071-UEN - Section 9Current protectionGenerator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 401Application manual
