GE D90 Plus Instruction Manual page 300

CONTROL ELEMENTS
290
The following settings are available for the direct under-reaching transfer trip (DUTT)
scheme.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the direct under-reaching transfer trip (DUTT) scheme.
Seal-In Delay
Range: 0.000 to 65.535 seconds in steps of 0.001
Default: 0.000 seconds
The DUTT OP FlexLogic™ operand is produced according to the scheme logic. A seal-in
time delay is applied to this operand for coping with noisy communication channels
such as a power line carrier. This setting specifies a minimum guaranteed duration for
the pulse. As this operand activates the trip table of the DUTT scheme, the trip
DUTT OP
operands (DUTT TRIP
A, DUTT TRIP
same period of time.
Communication Bits
Range: 1, 2, 4
Default: 2
This setting specifies the number of bits available on the communications channel. With
only one bit available, the scheme sends the direct under-reaching transfer trip
command on bit 1 (the
DUTT TX1
received on bit 1 (the RX1
provided by the phase selector to assert the trip operands
C, and
TRIP DUTT TRIP 3P).
RX1, RX2, RX3, RX4
Range: any FlexLogic™ operand
Default: OFF
These settings allow the user to select the FlexLogic™ operands that represent the
receive signals for the scheme. Typically input contacts interfacing with a signaling
system are used.
The DUTT scheme requires a secure and dependable signaling system. For this reason, a
series-parallel combination of receive signal contacts is often used. This is accomplished
by using a multi-bit communications system to transmit redundant copies of the
transmit signal (often via different paths) and building appropriate security logic (such as
series (AND gate) or two-out-of-three voting logic) with FlexLogic™. The
settings should be associated with the final (secure) transmit signals.
These settings are used in the following manner.
– Single bit applications: only
– Two-bit applications:
– Four-bit applications:
In multi-terminal applications, the receive signals from two or more remote terminals
should be connected through OR gates in protection FlexLogic™ and the resulting
signals configured as the RX1 through
Events
Range: Enabled, Disabled
Default: Enabled
This setting enables and disables the logging of direct under-reaching transfer trip
(DUTT) scheme events in the sequence of events recorder.
The direct under-reaching transfer trip (DUTT) scheme logic is shown below.
C, and
B, DUTT TRIP DUTT TRIP
operand) and responds to the direct trip command
setting). The scheme uses only local fault type identification
is used.
RX1
and must be used.
RX1 RX2
through must be used.
RX1 RX4
settings.
RX4
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
3P) are sealed-in for the
(DUTT TRIP
A, DUTT TRIP B, DUTT
to
RX1 RX4