Alstom MiCOM P546 - 2.17.2 IMx fallback mode

P54x/EN AP/La4 Application Notes
(AP) 6-48 MiCOM P543, P544, P545 & P546
AP
Channel
mode
setting
Application
Typical delay
(ms)
Maximum
(ms)
Comments
Direct Fiber 3 to 7 9
Assuming no
repeaters (no source
of digital “noise”)
Permissive
Multiplexed Link 5 to 8 + MUX 12 + MUX
For channel bit error
rate up to 1 x 10
-3
Direct Fiber 4 to 8 10
Assuming no
repeaters (no source
of digital “noise”)
Direct
Intertrip
Multiplexed link 6 to 8 + MUX 13 + MUX
For channel bit error
rate up to 1 x 10
-3
These figures are for InterMiCOM
64
used as a standalone feature. For use with differential
message, add 2 ms for permissive mode and 4 ms for direct intertrip at 64 Kb/sec.
When using InterMiCOM
64
to implement Aided Scheme 1 or Aided Scheme 2, it is suggested
to assume a conservative worst-case channel delay of 15 ms (pickup and reset delay), for
the purposes of blocking and reversal guard calculations. The delay of the multiplexer
should be added if applicable, taking into account longer standby path re-routings which
might be experienced in the event of self-healing in a SONET/SDH telecomms network.
When using InterMiCOM
64
as a standalone feature in 3-terminal applications, where fallback
to “chain” topology is possible in the event of failure of one communications leg in the
triangle, longer times may be experienced. In fallback mode, retransmission of the
messages occurs so the path length is doubled. Overall command times to the final end can
be doubled.
2.17.2 IMx fallback mode
Whe
n the ‘Default’ setting is selected, the following ‘IMx Default Value’ settings are
recommended: For Intertripping schemes set 0, for Blocking schemes set 1. In Permissive
applications, the user may prefer to latch the last healthy received state for a period of time.