CHAPTER 8: APPLICATION OF SETTINGS SETTINGSG60 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL 8-118Figure 8-3: Third harmonic neutral undervoltage field measurementsThe element is accurate for levels as low as 0.25 volts, secondary. In this case, the pickup setting isEq. 8-32The third harmonic dips below the pickup setting between 95 and 105 megawatts. The element needs to be blocked overthis range. A margin of 5% is added to the relay settings. The values for maximum and minimum power areEq. 8-33Eq. 8-34Voltage supervision is given a setting of 0.8 pu in order to prevent maloperation during a sustained undervoltage condition.A time delay of five seconds is to be applied. If required, the element can be blocked when the machine is offline. Make thefollowing changes in the EnerVista software or the front panel SETTINGS GROUPED ELEMENTS SETTING GROUP 1 STATOR GROUND 3RD HARM NTRL UNDERVOLTAGE menu.8.2.11 OverexcitationThis protection is to be set to coordinate with the manufacturer’s excitation capability curves. For the example system, thecombined generator/GSU limit curve is shown as follows.
