5-182 L60 Line Phase Comparison System GE Multilin5.5 GROUPED ELEMENTS 5 SETTINGS5• WATTMETRIC GND FLT 1 OV PKP: This setting specifies the minimum zero sequence voltage supervising the direc-tional power measurement. This threshold should be higher than possible unbalance during normal operation of thesystem. Typically, this setting would be selected at 0.1 to 0.2 pu for the ungrounded or resonant grounded systems,and at 0.05 to 0.1 pu for solidly or resistor-grounded systems. When using externally supplied voltage via the auxiliaryvoltage channel, 1 pu is the nominal voltage of this channel as per VT bank settings. When using internally calculatedneutral voltage, 1 pu is the nominal phase to ground voltage as per the VT bank settings.• WATTMETRIC GND FLT 1 CURR: The element responds to the neutral current (that is, three times zero-sequencecurrent), either calculated internally from the phase currents or supplied externally via the ground CT input from moreaccurate sources such as the core balanced CT. This setting allows selecting the source of the operating current.• WATTMETRIC GND FLT 1 OC PKP: This setting specifies the current supervision level for the measurement of thezero-sequence power.• WATTMETRIC GND FLT 1 OC PKP DEL: This setting specifies delay for the overcurrent portion of this element. Thedelay applies to the WATTMETRIC 1 PKP operand driven from the overcurrent condition.• WATTMETRIC GND FLT 1 PWR PKP: This setting specifies the operating point of the element. A value of 1 pu is aproduct of the 1 pu voltage as specified for the overvoltage condition of this element, and 1 pu current as specified forthe overcurrent condition of this element.• WATTMETRIC GND FLT 1 REF PWR: This setting is used to calculate the inverse time characteristic delay (definedby Sref in the following equations). A value of 1 pu represents the product of a 1 pu voltage (as specified in the overvolt-age condition for 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 poweris calculated as:(EQ 5.20)where * indicates complex conjugate. By varying the element characteristic angle (ECA), the element can be made torespond to forward or reverse direction in inductive, resistive, or capacitive networks as shown in the Wattmetric char-acteristic angle response diagram.• WATTMETRIC GND FLT 1 PWR PKP DEL: This setting defines a definite time delay before the inverse time charac-teristic is activated. If the curve selection is set as “Definite Time”, the element would operate after this security timedelay. If the curve selection is “Inverse” or one of the FlexCurves, the element uses both the definite and inverse timetimers simultaneously. The definite time timer, specified by this setting, is used and when expires it releases theinverse time timer for operation (torque control).• WATTMETRIC GND FLT 1 CURVE: This setting allows choosing one of three methods to delay operate signal once allconditions are met to discriminate fault direction.The “Definite Time” selection allows for a fixed time delay defined by the WATTMETRIC GND FLT 1 PWR PKP DEL set-ting.The “Inverse” selection allows for inverse time characteristics delay defined by the following formula:(EQ 5.21)where m is a multiplier defined by the multiplier setting, Sref is the multiplier setting, and Sop is the operating power atthe time. This 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 5.22)Again, the FlexCurve timer starts after the definite time timer expires.S_op Re V n I n 1 ECA∠×( )∗( )=t m S refS op----------×=t FlexCurve S opS ref---------- =
