CHAPTER 6: COMMUNICATIONS DIRECT INPUTS AND OUTPUTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 151
additional switching equipment is required as the IEDs are connected directly in a ring or
redundant (dual) ring configuration. This feature is optimized for speed and intended for
pilot-aided schemes, distributed logic applications, or the extension of the input/output
capabilities of a single device.
The D90
Plus
provides 96 direct inputs and 96 direct outputs per communication channel.
Direct inputs and outputs are intended for exchange of status information (inputs and
outputs) between UR
Plus
-series devices connected directly via inter-relay communications
cards. The mechanism is very similar to IEC 61850 GSSE, except that communications
takes place over a non-switchable isolated network and is optimized for speed. All inter-
relay communication cards support two channels, allowing direct output messages to be
sent from both channels simultaneously. This effectively sends direct output messages
both ways around a ring configuration. Messages are resent (forwarded) when it is
determined that the message did not originate at the receiver.
Direct output message timing is similar to GSSE message timing. Integrity messages (with
no state changes) are sent at least every 1000 ms at 64 kbps or 500 ms at 128 kbps.
Messages with state changes are sent within the main pass scanning the inputs and
asserting the outputs unless the communication channel bandwidth has been exceeded.
Two self-tests are performed and signaled by the following FlexLogic operands:
• CH1 DIR IO RING BREAK and CH2 DIR IO RING BREAK — These operands indicate that direct
output messages sent from a UR
Plus
-series device are not being received back by the
device.
• CH1 DIR DEV 1 OFF to CH1 DIR DEV 16 OFF and CH2 DIR DEV 1 OFF to CH2 DIR DEV 16 OFF —
These operands indicate that direct output messages from the corresponding direct
device are not being received.
Direct input and output settings are similar to remote input and output settings. The
equivalent of the remote device name strings for direct inputs and outputs is the
Direct
Device ID. Delivery time for direct input and output messages is approximately 0.2 of a
power system cycle at 128 kbps and 0.4 of a power system cycle at 64 kbps, per each
“bridge.”
NOTE:
Direct inputs and outputs exchange between UR
Plus
-series IEDs is supported over the
inter-relay communication card's G.703, C37.94, direct fiber, and RS422 interfaces. Direct
inputs and outputs exchange with UR-series IEDs is supported on the C37.94, direct fiber,
and RS422 interfaces.
Direct input and output configuration
Select the Settings > Communications > Direct I/O menu to open the direct inputs and
outputs configuration window.
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