5-238 F60 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS5WATTMETRIC GND FLT 1 REF PWR — This setting is used to calculate the inverse time characteristic delay (defined by Sref inthe following equations). A value of 1 pu represents the product of a 1 pu voltage (as specified in the overvoltage conditionfor this element) and a 1 pu current (as specified in the overcurrent condition for this element.WATTMETRIC GND FLT 1 ECA — This setting adjusts the maximum torque angle of the element. The operating power iscalculated as:S_op = Re(Vn (In x 1∠ECA)*) Eq. 5-19where* indicates complex conjugateBy varying the element characteristic angle (ECA), the element can be made to respond to forward or reverse direction ininductive, resistive, or capacitive networks as shown in the Wattmetric Characteristic Angle Response diagram.WATTMETRIC GND FLT 1 PWR PKP DEL — This setting defines a definite time delay before the inverse time characteristic isactivated. If the curve selection is set as “Definite Time”, the element operates after this security time delay. If the curveselection is “Inverse” or one of the FlexCurves, the element uses both the definite and inverse time timers simultaneously.The definite time timer, specified by this setting, is used and when expires it releases the inverse time timer for operation(torque control).WATTMETRIC GND FLT 1 CURVE — Choose one of three methods to delay the operate signal once all conditions are met todiscriminate fault direction.The “Definite Time” selection allows for a fixed time delay defined by the WATTMETRIC GND FLT 1 PWR PKP DEL setting.The “Inverse” selection allows for inverse time characteristics delay defined by the following formula:Eq. 5-20wherem is a multiplier defined by the multiplier settingSref is the multiplier settingSop is the operating power at the timeThis timer starts after the definite time timer expires.The four FlexCurves allow for custom user-programmable time characteristics. When working with FlexCurves, theelement uses the operate to pickup ratio, and the multiplier setting is not applied:Eq. 5-21Again, the FlexCurve timer starts after the definite time timer expires.
