GE D90 Plus Instruction Manual page 220

GROUPED PROTECTION ELEMENTS
210
first step is similar to the power swing blocking sequence. After the timer specified by the
setting times out, latch 1 is set as long as the impedance stays within the
Pickup Delay 1
outer characteristic.
If afterwards, at any time (given the impedance stays within the outer characteristic), the
locus enters the middle characteristic but stays outside the inner characteristic for a
period of time defined by the
stays inside the outer characteristic. If afterwards, at any time (given the impedance stays
within the outer characteristic), the locus enters the inner characteristic and stays there for
a period of time defined the Pickup Delay 3 setting, latch 2 is set as long as the impedance
stays inside the outer characteristic; the element is now ready to trip.
If the Early trip mode is selected, the
sealed-in for the interval specified by the
selected, the element waits until the impedance locus leaves the inner characteristic, then
times out for the
Pickup Delay 2
The trip operand is set later, when the impedance locus leaves the outer characteristic.
The two-step mode of operation is similar to the three-step mode with two exceptions.
1. The initial stage monitors the time spent by the impedance locus between the outer
and inner characteristics.
2. Second, the stage involving the
integrate the blocking
FlexLogic™ operands with other protection functions and output contacts in order to
make this element fully operational.
The element can be set to use either lens (mho) or rectangular (quad) characteristics as
illustrated below. When set to "Mho", the element applies the right and left blinders as well.
If the blinders are not required, their settings should be set high enough to effectively
disable the blinders.
Figure 187: Power swing detect mho operating characteristic
setting, latch 2 is set as long as the impedance
Pickup Delay 2
POWER SWING TRIP
Seal-In Delay
setting and sets latch 4; the element is now ready to trip.
timer is bypassed. It is up to the user to
Pickup Delay 2
(POWER SWING BLOCK) and tripping
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
operand is set immediately and
setting. If the "Delayed" trip mode is
(POWER SWING
TRIP)