CHAPTER 5: SETTINGS CONTROL ELEMENTSF60 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 5-2515DIR POWER 1 CALIBRATION — This setting allows the relay characteristic angle to change in steps of 0.05°. This is usefulwhen a small difference in VT and CT angular errors is to be compensated to permit more sensitive settings. This settingvirtually enables calibration of the directional power function in terms of the angular error of applied VTs and CTs. Theelement responds to the sum of the DIR POWER 1 RCA and DIR POWER 1 CALIBRATION settings.DIR POWER 1 STG1 SMIN — This setting specifies the minimum power as defined along the relay characteristic angle (RCA)for the stage 1 of the element. The positive values imply a shift towards the operate region along the RCA line; the negativevalues imply a shift towards the restrain region along the RCA line. See the Directional Power Sample Applications figurefor details. Together with the RCA, this setting enables a wide range of operating characteristics. This setting applies tothree-phase power and is entered in per-unit (pu) values. The base quantity is 3 x VT pu base x CT pu base.For example, a setting of 2% for a 200 MW machine is 0.02 × 200 MW = 4 MW. If 13.8kV is line voltage and 10 kA is aprimary CT current, the source pu quantity is 239 MVA, and thus, SMIN needs to be set at 4 MW / 239 MVA = 0.0167 pu ≈0.017 pu. If the reverse power application is considered, RCA = 180° and SMIN = 0.017 pu.The element drops out if the magnitude of the positive-sequence current becomes virtually zero, that is, it drops below thecutoff level.DIR POWER 1 STG1 DELAY — This setting specifies a time delay for stage 1. For reverse power or low forward powerapplications for a synchronous machine, stage 1 is typically applied for alarming and stage 2 for tripping.Figure 5-136: Sensitive directional power logic5.8 Control elements5.8.1 OverviewControl elements are used for control rather than protection. See the Introduction to Elements section at the beginning ofthis chapter for information.5.8.2 Trip busSETTINGS CONTROL ELEMENTS TRIP BUS TRIP BUS 1(6) TRIP BUS 1 TRIP BUS 1FUNCTION: DisabledRange: Enabled, Disabled
