GE P24DM User Manual

With Current Differential protection enabled
The 8 bits of both Logical Channels (Ch1 and Ch2) are available, Logical Channel 1 is assigned to Physical Channel
1, and Logical Channel 2 is assigned to Physical Channel 2, so 16 duplex commands are potentially available.
To implement a true redundancy scheme, however, signals on Logical Channel 2 should be assigned identically to
those on Logical Channel 1. Upon reception, the matched bits should be logically ‘OR’ed when mapped in the PSL.
In this application the command bits are packaged with the Current Differential signals. Current Differential
protection and the IM64 signalling will be maintained in the event of a single communication channel failure.
With Current Differential protection disabled
The 8 bits of both Logical Channels (Ch1 and Ch2) are used. The bits of both Logical Channels are all assigned both
to Physical Channel 1 and to Physical Channel 2, so that 16 duplex commands (IM64 Ch1 bits 1-8 and IM64 Ch2
bits 1-8) can be communicated between terminals in IM64 messages with full redundancy of both Logical
Channels in the event of failure of either Physical Channel.
3.1.5
THREE-TERMINAL IM64 OPERATION
The protection signalling connection requirement for products operating as a Three Terminal scheme is that
Physical Channels labelled as Ch1 should be connected to Physical Channels labelled as Ch2 . That means that a
local Ch1 Tx connects to a remote Ch2 Rx, and the corresponding Ch1 Rx and Ch2 Tx are connected together as
shown in the earlier figure (Fibre Teleprotection Connections for a Three Terminal Scheme).
With Current Differential protection enabled
8 IM64 Fibre Teleprotection Commands can be transferred between pairs of terminals. Integrity of the Current
Differential protection and the IM64 schemes can be maintained in the event of a communications link failure by
reverting to a master-slave-slave configuration where the terminal with healthy communications with the other
terminals makes the tripping decision and sends intertrip commands to the other two. The master can also send 8
IM64 teleprotection commands to the remote terminals. The same commands are sent to both terminals .
In this IM64 application, the 8 bits of both Logical Channels (Ch1 and Ch2) are available, Logical Channel 1 is
assigned to Physical Channel 1, and Logical Channel 2 is assigned to Physical Channel 2. To implement a true
redundancy scheme that will work correctly, the same IM64 bit assignments should be made at all three terminals
and the signals on Logical Channel 2 should be assigned identically to those on Logical Channel 1. Upon reception,
the matched bits should be logically ‘OR’ed when mapped in the PSL.
In this application the command bits are packaged with the Current Differential signals. Current Differential
protection and the IM64 signalling will be maintained in the event of a single communication channel failure.
With Current Differential protection disabled
This Three Terminal scheme uses a triangulation approach and is designed to function if a communications link
between two terminals is not present or is degraded. 8 duplex teleprotection commands are available between
any pair of terminals even if one communication channel fails.
Logical Channel 1 is associated with Physical Channel 1, and Logical Channel 2 is associated with Physical Channel
2.
Consider a Three terminal scheme where the terminals are referenced as Local, Remote1, and Remote2. Remote 1
correlates to Ch1, and Remote 2 correlates to Ch2. The Local terminal will send the commands that it wants
Remote 1 to act on to both Remote 1 and Remote 2. Upon receipt, Remote 1 acts upon the commands that the
Local terminal wants it to use. Remote 1 also packages the commands that it wants Remote 2 to use, together
with a copy of the commands that Local wants Remote 2 to use, and also the commands it wants Local to use.
Remote 1 sends the message to Remote2. Remote 2 acts similarly. The same process occurs in the opposite
direction around the ring, so in the event of a single channel failure, and if all terminals have the same mappings
for the 8 IM64 bits integrity will be maintained for all 8 duplex commands between connected terminals.
In a triangulated scheme, at each terminal, Logical Channel 1 commands are assigned to Physical Channel 1, and
Logical Channel 2 commands are assigned to Physical Channel 2. At each terminal, the eight IM64 commands
P543i/P545i Chapter 20 - Fibre Teleprotection
P54x1i-TM-EN-1 505

GE P24DM Specifications

General

Brand	GE
Model	P24DM
Category	Control Unit
Language	English