CHAPTER 5: SETTINGS SYSTEM SETUPD60 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 5-13955.5.6.2 FlexCurve configuration with EnerVista softwareThe EnerVista software allows for easy configuration and management of FlexCurves and their associated data points.Prospective FlexCurves can be configured from a selection of standard curves to provide the best approximate fit, thenspecific data points can be edited afterwards. Alternately, curve data can be imported from a specified file (.csv format) byselecting the EnerVista Import Data From setting (Settings > System Setup > FlexCurves > FlexCurve).Curves and data can be exported, viewed, and cleared by clicking the appropriate buttons. FlexCurves are customized byediting the operating time (ms) values at pre-defined per-unit current multiples. Note that the pickup multiples start at zero(implying the "reset time"), operating time below pickup, and operating time above pickup.5.5.6.3 Recloser curve editingRecloser curve selection is special in that recloser curves can be shaped into a composite curve with a minimum responsetime and a fixed time above a specified pickup multiples. There are 41 recloser curve types supported. These definiteoperating times are useful to coordinate operating times, typically at higher currents and where upstream anddownstream protective devices have different operating characteristics. The recloser curve configuration window shownhere appears when the Initialize From setting in the EnerVista software is set to “Recloser Curve” and the InitializeFlexCurve button is clicked.Figure 5-63: Recloser curve initialization5.5.6.4 ExampleA composite curve can be created from the GE_111 standard with MRT = 200 ms and HCT initially disabled and thenenabled at eight times pickup with an operating time of 30 ms. At approximately four times pickup, the curve operatingtime is equal to the MRT and from then onwards the operating time remains at 200 ms.The relay using a given FlexCurve applies linear approximation for times between the user-entered points. Takecare when setting the two points that are close to the multiple of pickup of 1; that is, 0.98 pu and 1.03 pu. It isrecommended to set the two times to a similar value, otherwise the linear approximation can result in undesiredbehavior for the operating quantity that is close to 1.00 pu.The Multiplier and Adder settings only affect the curve portion of the characteristic and not the MRT and HCTsettings. The HCT settings override the MRT settings for multiples of pickup greater than the HCT ratio.
