GE L90 Instruction Manual page 562

CONTROL ELEMENTS
DCUB LOG PICKUP DELAY
amount of time that the loss-of-guard without receipt of permissive trip must be present before the logic provides
permission to operate if a forward fault is detected. It is set relatively short, but long enough to ride through the transition
period of loss-of-guard with the receipt of a permissive signal that occurs with a normal trip. Typical setting values are
from 4 to 32 ms. For most cases, a value of 8 ms can be used.
The tripping or unblocking window for loss-of-guard without permission is the difference between the
and
WINDOW DCUB LOG PICKUP DELAY
after loss-of-guard was received, when the
has permission to operate if a forward fault is sensed, and no reverse faults or transient blocking.
GUARD HEALTHY RESET DELAY
is restored that the guard signal must be present before the directional comparison unblocking scheme is put back in
service. This reset timer allows the scheme to ride through any chattering in the channel. Typical values are from 100 to
500 ms, with a value of 150 ms commonly used.
DCUB LOG TRIP WINDOW
amount of time from when any loss-of-guard signal is received until the directional comparison unblocking scheme is
locked out without the presence of any
expires, creating a blocking signal for all scheme functions and disabling the scheme until the guard signal is restored and
the
GUARD HEALTHY RESET DELAY
setting of about 150 ms can be used.
DCUB SEAL-IN DELAY
unblocking scheme logic. The
operand runs the trip table of the directional comparison unblocking scheme, the
trip operands are sealed-in for the same period of time.
DCUB TRIP 3P
5 DCUB NO OF COMM BITS
scheme. With only one bit available, the scheme sends the direct under-reaching transfer trip command on bit 1
operand) and responds to the direct trip command received on bit 1 (
type identification provided by the phase selector to assert the
output operands.
through
DCUB RX1
receive signals for the scheme. Contact inputs interfacing with a signaling system(s) are typically used. These settings must
be used in conjunction with the loss-of-guard signals, otherwise the scheme does not unblock and thus fails to operate.
In single-bit applications,
applications,
DCUB RX1
through
DCUB LOG1
guard receive signals for the scheme. Contact inputs interfacing with a signaling system(s) are typically used. Each loss-of-
guard signal must correspond to the same receive signal from the same communications channel (that is,
must be from the same communications channel, and the same for channels 2, 3 and 4, if used).
In single-bit applications,
with
DCUB RX2 DCUB LOG2
5-376
— This setting represents the directional comparison unblocking duration time delay. It is the
timers. For the default settings, this difference is 150 – 8 = 142 ms and occurs 8 ms
DCUB LOG PICKUP DELAY
— This setting represents the guard healthy security time delay. It is the time after the channel
— This setting represents the directional comparison unblocking lockout time delay. It is the
to
RX1 RX4
timer expires. Typical values for this setting are from 160 to 180 ms; for most cases, a
— The output FlexLogic operand
DCUB SEAL-IN DELAY
— This setting specifies the number of bits available on the communications channel for the
— These settings allow the user to select the FlexLogic operands to represent the permission
DCUB RX4
must be used. In two-bit applications,
DCUB RX1
, , , and
DCUB RX2 DCUB RX3
— These settings allow the user to select the FlexLogic operands to represent the loss-of-
DCUB LOG4
and
DCUB RX1 DCUB LOG1
must be used. In four-bit applications, all receive and loss-of-guard signals must be used.
timer has timed out. During this interval, the scheme
receive signal or any forward element. This timer seals-in when it
(DCUB OP) is produced according to the directional comparison
defines a minimum guaranteed duration of the
DCUB RX1
DCUB TRIP A, DCUB TRIP
DCUB RX1
must be used.
DCUB RX4
must be used. In two-bit applications,
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
DCUB LOG TRIP
pulse. As this
DCUB OP
DCUB TRIP A, DCUB TRIP B, DCUB TRIP
setting). The scheme uses only local fault
C, and
B, DCUB TRIP DCUB TRIP 3P
and must be used. In four-bit
DCUB RX2
RX1
with
DCUB RX1 DCUB LOG1
C, and
(DCUB TX1
and
LOG1
and