Phase directional time overcurrent relay (67) – directional toward the Transmission Generator step-up system installed – transformer(s) Generator bus voltage corresponding The overcurrent element shall be set greater than 130% of the on generator-side of connected to to 1.0 per unit of the high-side calculated current derived from the maximum aggregate the GSU asynchronous 12 nominal voltage times the turns ratio nameplate MVA output at rated power factor (including the transformer generators only of the generator step-up transformer Mvar output of any static or dynamic reactive power devices) (including based installations) If the relay is installed on the high-side of the GSU transformer use Option 19 A different application starts below Phase overcurrent 1.0 per unit of the winding nominal The overcurrent element shall be set greater than 150% of the relay (51) applied at 13a voltage of the unit auxiliary calculated current derived from the unit auxiliary transformer the high-side transformer maximum nameplate MVA rating terminals of the OR Unit auxiliary UAT, for which transformer(s) (UAT) The overcurrent element shall be set greater than 150% of the operation of the Unit auxiliary transformer bus unit auxiliary transformer measured current at the generator relay will cause the 13b voltage corresponding to the maximum gross MW capability reported to the Transmission associated generator measured current Planner to trip. A different application starts on the next page
Generator step-up transformer(s) connected to asynchronous generators only (including installations) Phase directional time overcurrent relay (67) – directional toward the Transmission system – installed on generator-side of the GSU transformer If the relay is installed on the high-side of the GSU transformer use Option 19 12 Generator bus voltage corresponding to 1.0 per unit of the high-side nominal voltage times the turns ratio of the generator step-up transformer The overcurrent element shall be set greater than 130% of the calculated current derived from the maximum aggregate nameplate MVA output at rated power factor (including the Mvar output of any static or dynamic reactive power devices) A different application starts below Unit auxiliary transformer(s) (UAT) Phase overcurrent relay (51) applied at the high-side terminals of the UAT, for which operation of the relay will cause the associated generator to trip. 13a 1.0 per unit of the winding nominal voltage of the unit auxiliary transformer The overcurrent element shall be set greater than 150% of the calculated current derived from the unit auxiliary transformer maximum nameplate MVA rating OR 13b Unit auxiliary transformer bus voltage corresponding to the measured current The overcurrent element shall be set greater than 150% of the unit auxiliary transformer measured current at the generator maximum gross MW capability reported to the Transmission Planner A different application starts on the next page based