5-298
L90 Line Current Differential System
GE Multilin
5.7 CONTROL ELEMENTS
5 SETTINGS
5
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 (
DUTT TX1
through
DUTT TX4
) that are used to transmit the direct under-reaching
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 (
DUTT OP
) is produced according to the DUTT scheme logic. A
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
is a minimum guaranteed duration of the
DUTT OP
pulse. As this operand activates the Trip
Table of the DUTT scheme, the trip operands
DUTT TRIP A
,
B
,
C
and
3P
are sealed-in for the same period of time.
•
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 (
DUTT TX1
oper-
and) and responds to the direct trip command received on bit no. 1 (
DUTT RX1
setting). The scheme uses only local
fault type identification provided by the Phase Selector to assert the output operands
DUTT TRIP A
,
B
,
C
and
3P
(see
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
TX
signal (often via different paths) and building appropriate security logic (such as series
(AND gate) or 2-out-of-3 voting logic) with FlexLogic. The
DUTT RX1(4)
settings should be associated with the final
(secure) TX signals.
Summary of Contents for UR Series L90
Page 652: ...A 16 L90 Line Current Differential System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 772: ...B 120 L90 Line Current Differential System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 802: ...C 30 L90 Line Current Differential System GE Multilin C 7 LOGICAL NODES APPENDIX C C ...
Page 812: ...D 10 L90 Line Current Differential System GE Multilin D 1 IEC 60870 5 104 APPENDIX D D ...
Page 824: ...E 12 L90 Line Current Differential System GE Multilin E 2 DNP POINT LISTS APPENDIX E E ...
Page 834: ...F 10 L90 Line Current Differential System GE Multilin F 3 WARRANTY APPENDIX F F ...
Page 846: ...xii L90 Line Current Differential System GE Multilin INDEX ...
