GE D90 Plus Instruction Manual page 222

GROUPED PROTECTION ELEMENTS
212
the timer specified by the
impedance stays within the 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
impedance 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
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
and sealed-in for the interval set by the
mode is selected, the element waits until the impedance locus leaves the inner
characteristic, then times out for the
element is now 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 time spent by the impedance locus between the outer and
inner characteristics. Second, the stage involving the
It is up to the user to integrate the blocking
TRIP) FlexLogic operands with other protection functions and output contacts in
SWING
order to make this element fully operational.
The element can be set to use either lens (mho) or rectangular (quadrilateral)
characteristics, as shown in the figure. When set to "Mho," the element applies the right
and left blinders as well. If the blinders are not required, set their settings high enough to
effectively disable the blinders.
Figure 188: Power swing detect mho operating characteristic
setting times out, latch 1 is set as long as the
Delay 1 Pickup
setting, latch 2 is set as long as the
Delay 2 Pickup
POWER SWING TRIP
Seal-In Delay
Pickup Delay 2
(POWER SWING
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
setting,
Delay 3 Pickup
operand is set immediately
setting. If the "Delayed" trip
setting and sets latch 4; the
timer is bypassed.
Delay 2 Pickup
BLOCK) and tripping (POWER