CHAPTER 5: SETTINGS GROUPED ELEMENTSL90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 5-2295Figure 5-122: Power swing detect quadrilateral operating characteristicsThe FlexLogic output operands for the power swing detect element are as follows:• POWER SWING OUTER, POWER SWING MIDDLE, POWER SWING INNER, POWER SWING TMR2 PKP, POWER SWING TMR3 PKP, andPOWER SWING TMR4 PKP are auxiliary operands that facilitate testing and special applications• POWER SWING BLOCK blocks selected protection elements, such as distance functions• POWER SWING UN/BLOCK blocks those protection elements that are intended to be blocked under power swings, butsubsequently unblocked when a fault occurs after the power swing blocking condition has been established• POWER SWING 50DD indicates that an adaptive disturbance detector integrated with the element has picked up. Thisoperand triggers on faults occurring during power swing conditions. This includes both three-phase and single-pole-open conditions.• POWER SWING INCOMING indicates an unstable power swing with an incoming locus (the locus enters the innercharacteristic)• POWER SWING OUTGOING indicates an unstable power swing with an outgoing locus (the locus leaving the outercharacteristic). This operand can be used to count unstable swings and take certain action only after a pre-definednumber of unstable power swings.• POWER SWING TRIP is a trip commandThe settings for the power swing detect element are as follows.POWER SWING FUNCTION — This setting enables and disables the power swing detection element. The setting applies toboth power swing blocking and out-of-step tripping functions.POWER SWING SOURCE — The source setting identifies the signal source for both blocking and tripping functions.POWER SWING SHAPE — This setting selects the shapes (either “Mho” or “Quad”) of the outer, middle, and innercharacteristics of the power swing detect element. The operating principle is not affected. The “Mho” characteristics usethe left and right blinders.
