GE D60 Instruction Manual page 455

5 SETTINGS
MESSAGE
This scheme uses an under-reaching Zone 1 distance element to key a transfer trip signal(s) to the remote end(s), where
on receipt, the DUTT pilot scheme operates without additional protection supervision. For proper operation of the scheme
the Zone 1 phase and ground distance elements must be enabled, configured, and set per rules of distance relaying.
In single-pole tripping applications, the scheme uses local fault type identification provided by the Phase Selector together
with information received from the remote terminal(s). The latter may be coded into one, two or four bits over the communi-
cations channel.
The scheme generates output operands (
signals to the remote end(s). Choices of communications channel include remote inputs/outputs and telecommunications
interfaces. When used with telecommunications facilities the output operands should be assigned to operate output con-
tacts connected to assert the individual bits at the interface.
To make the scheme a fully operational stand-alone feature, the scheme output operands must be configured to interface
with other relay functions, output contacts in particular. Typically, the output operands should be programmed to initiate a
trip, breaker fail, and autoreclose, and drive a user-programmable LED as per user application. When used in conjunction
with the trip output element, the scheme is pre-configured to initiate trip, breaker fail, and single-pole autoreclose actions.
• DUTT SCHEME BLOCK: This setting allows the user to assign any FlexLogic operand to block the scheme. Contact
inputs from a pilot cut-out switch are typically used for this purpose.
• DUTT SEAL-IN DELAY: The output FlexLogic operand (
seal-in time delay is applied to this operand for coping with noisy communication channels such as a power line carrier.
The
DUTT SEAL-IN DELAY
Table of the DUTT scheme, the trip operands
• DUTT NO OF COMM BITS: 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 no.1 (
and) and responds to the direct trip command received on bit no. 1 (
fault type identification provided by the Phase Selector to assert the output operands
Chapter 8: Theory of Operation for details on the use of communication channels).
• DUTT RX1 through DUTT RX4: 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
(AND gate) or 2-out-of-3 voting logic) with FlexLogic. The
(secure) TX signals.
GE Multilin
DUTT SCHEME EVENTS:
Disabled
through
DUTT TX1
is a minimum guaranteed duration of the
DUTT TRIP A
signal (often via different paths) and building appropriate security logic (such as series
TX
D60 Line Distance Protection System
Range: Disabled, Enabled
) that are used to transmit the direct under-reaching
DUTT TX4
) is produced according to the DUTT scheme logic. A
DUTT OP
pulse. As this operand activates the Trip
DUTT OP
, , and are sealed-in for the same period of time.
B C 3P
setting). The scheme uses only local
DUTT RX1
settings should be associated with the final
DUTT RX1(4)
5.7 CONTROL ELEMENTS
oper-
DUTT TX1
, , and (see
DUTT TRIP A B C 3P
5-321
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