GE D30 Instruction Manual

Also see for D30 series: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

CHAPTER 5: SETTINGS GROUPED ELEMENTSD30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 5-2115function does not trigger on power swings, but is capable of detecting faster disturbances—faults in particular—that canoccur during power swings. Operation of this dedicated disturbance detector is signaled via the POWER SWING 50DDoperand.The power swing detect element asserts two operands intended for blocking selected protection elements on powerswings: POWER SWING BLOCK is a traditional signal that is safely asserted for the entire duration of the power swing, andPOWER SWING UN/BLOCK is established in the same way, but resets when an extra disturbance is detected during the powerswing. The POWER SWING UN/BLOCK operand can be used for blocking selected protection elements if the intent is torespond to faults during power swing conditions.Different protection elements respond differently to power swings. If tripping is required for faults during power swingconditions, some elements can be blocked permanently (using the POWER SWING BLOCK operand), and others can beblocked and dynamically unblocked upon fault detection (using the POWER SWING UN/BLOCK operand).View the operating characteristic and logic figures along with the following discussion to understand the operation of theelement.The power swing detect element operates in three-step or two-step mode, as follows:• Three-step operation — The power swing blocking sequence essentially times the passage of the locus of thepositive-sequence impedance between the outer and the middle characteristic boundaries. If the locus enters theouter characteristic (indicated by the POWER SWING OUTER FlexLogic operand) but stays outside the middlecharacteristic (indicated by the POWER SWING MIDDLE FlexLogic operand) for an interval longer than POWER SWINGPICKUP DELAY 1, the power swing blocking signal (POWER SWING BLOCK FlexLogic operand) is established and sealed-in.The blocking signal resets when the locus leaves the outer characteristic, but not sooner than the POWER SWING RESETDELAY 1 time.• Two-step operation — If the two-step mode is selected, the sequence is identical to the three-step operation, but it isthe outer and inner characteristics that are used to time the power swing locus.The out-of-step tripping feature operates as follows for three-step and two-step power swing detection modes:• Three-step operation — The out-of-step trip sequence identifies unstable power swings by determining if theimpedance locus spends a finite time between the outer and middle characteristics and then a finite time betweenthe middle and inner characteristics. The first step is similar to the power swing blocking sequence. After timer POWERSWING PICKUP DELAY 1 times out, latch 1 is set as long as the impedance stays within the outer characteristic.If afterwards, at any time (given the impedance stays within the outer characteristic), the locus enters the middlecharacteristic but stays outside the inner characteristic for a period of time defined as POWER SWING PICKUP DELAY 2,latch 2 is set as long as the impedance stays inside the outer characteristic. If afterwards, at any time (given theimpedance stays within the outer characteristic), the locus enters the inner characteristic and stays there for a periodof time defined as POWER SWING PICKUP DELAY 3, latch 2 is set as long as the impedance stays inside the outercharacteristic; the element is now ready to trip.If the "Early" trip mode is selected, the POWER SWING TRIP operand is set immediately and sealed-in for the interval setby the POWER SWING SEAL-IN DELAY. If the "Delayed" trip mode is selected, the element waits until the impedance locusleaves the inner characteristic, then times out for the POWER SWING PICKUP DELAY 2 and sets latch 4; the element isnow ready to trip. The trip operand is set later, when the impedance locus leaves the outer characteristic.• Two-step operation — Similar to the three-step mode with two exceptions. First, the initial stage monitors the timespent by the impedance locus between the outer and inner characteristics. Second, the stage involving the POWERSWING PICKUP DELAY 2 timer is bypassed. It is up to the user to integrate the blocking (POWER SWING BLOCK) and tripping(POWER SWING TRIP) FlexLogic operands with other protection functions and output contacts in order to make thiselement fully operational.The element can be set to use either lens (mho) or rectangular (quadrilateral) characteristics, as shown in the figure. Whenset to “Mho,” the element applies the right and left blinders as well. If the blinders are not required, set their settings highenough to effectively disable the blinders.