When precision TCC coordination is not possible, the
Communication Enhanced
Coordination
(CEC) feature enables a group of IntelliRupter fault interrupters to share
the same coordination curve but open only the device closest to the fault. With CEC, more
IntelliRupter fault interrupters can be installed on a feeder, which reduces line-segment
size, so fewer customers will be involved when a fault is isolated.
Communication-enhanced coordination is a feature of the IntelliTeam SG
Automatic Restoration System, but because it’s a protection function, it operates even when
restoration is not enabled. Because CEC functionality is dependent on the underling
IntelliTeam SG system architecture, it is only available for IntelliRupter fault interrupt-
ers when the proper IntelliTeam SG license has been enabled.
CEC doesn’t have to be used by all the IntelliRupter fault interrupters on a feeder.
However, both IntelliRupter fault interrupters in a CEC pair must have CEC enabled, use
the correct General Profile (i.e. not Hot Line Tag), and have no errors. CEC messages
are sent to the source-side IntelliRupter fault interrupter. If that device is not ready,
CEC goes out of ready for that pair, and no further CEC messages are sent.
CEC can only be used by IntelliRupter fault interrupters that have a SpeedNet™ Radio
or fiber-optic transceiver because CEC operation requires a minimum bandwidth of
500 kbs and a latency of less than 10 ms.
When a CEC-configured IntelliRupter fault interrupter senses fault current, it sends a
curve-shift message to its source-side neighbor, asking that device to change to a slower
protection curve.
All the CEC-configured IntelliRupter fault interrupters sense fault at the same time
and send a curve-shift request to their source-side neighbor.
Only the IntelliRupter fault interrupter at the faulted line segment will not receive a
curve-shift message because it does not have a load-side neighbor sensing fault current.
It will not change to the slow protection curve and trip before the other IntelliRupter
fault interrupters.
The TCC graph in Figure 17 on page 35 shows how communication-enhanced
coordination relates to other protection curves on a feeder. The discrete TCCs coor-
dinate for IntelliRupter fault interrupters A1, A2, and A3. The other IntelliRupter fault
interrupters share TCC curve A4. When a fault event in a line segment protected by
one of the “A4” IntelliRupter fault interrupters crosses the pickup setting of the slow-
est IntelliRuper fault interrupter, all IntelliRupter fault interrupters sharing TCC A4
start communication-enhanced coordination. Sensing a fault, transmitting the curve-
shift command, and receiving the curve-shift command typically take less than 100
ms. (This time value is dependent on communication system latency—fiber-optic
transceivers operate faster, and radio repeater latency will slow transmission.) The
IntelliRupter fault interrupter closest to the fault opens on TCC A4. The other “A4”
IntelliRupter fault interrupters either did not sense fault current or have switched
to a slower TCC curve, so only the IntelliRupter fault interrupter protecting the
faulted line section opens for the fault. If the fault occurs in a line section protected
by an A1, A2, or A3 IntelliRupter fault interrupter, the appropriate TCC for that line
section will be used and source-side IntelliRupter fault interrupters will be coordinated
to stay closed for the duration of the fault.
When the open CEC-coordinated IntelliRupter fault interrupter is testing fault
persistence, it sends messages to its source-side neighbor to keep the slower curve in use.
If the fault is persistent and the IntelliRupter fault interrupter trips, it sends an
Event
Done
command to all the CEC IntelliRupter fault interrupters, and they curve-shift back
to the fast curve (TCC A4) and become ready for a second event. If the fault is temporary
and the IntelliRupter fault interrupter can close, the
Event Done
command will be sent
after the
Sequence
Timer
expires.
CEC Operation
34 S&C Instruction Sheet 766-530
Communication Enhanced Coordination
