Telecommunication Channel Monitoring - Toshiba GRL100-701B Instruction Manual

3.3.7

Telecommunication Channel Monitoring

Signal channel monitoring for current differential protection
The telecommunication channel is monitored at each terminal by employing a cyclic redundancy
check and fixed bit check of the received data. The check is carried out for every sampling.
If a data failure occurs between the local terminal and remote terminal 1 and lasts for ten
seconds, failure alarms "Com1 fail" and "Com1 fail-R" are issued at the local and remote
terminals respectively. "Com1 fail" is a failure detected by the local terminal relay, and "Com1
fail-R" is a failure detected by the remote terminal relay. If the failure occurs between the local
terminal and remote terminal 2, "Com2 fail" and "Com2 fail-R" are issued.
Note: The remote terminal 1 and 2 are those with which the local communication port 1
(CH1) and 2 (CH2) are linking with.
In the case that the GRL100 is linked directly to a dedicated optical fiber communication circuit,
sending and receiving signal levels are monitored and error messages "TX1 level err" of CH1 or
"TX2 level err" of CH2 for sending signal and "RX1 level err" of CH1 or "RX2 level err" of CH2
for receiving signal are output when the levels fall below the minimum allowed.
In the communication setup in which the GRL100 receives the clock signal from the multiplexer,
an error message "CLK1 fail" of CH1 or "CLK2 fail" of CH2 is output when the signal is
interrupted.
Note: Messages "Com2 fail", "RX2 level err", "TX2 level err" and "CLK2 fail" are valid
in three-terminal applications.
If the ready signal of the remote terminal relay via CH1 or CH2 is OFF during ten seconds or
more, the message 'Term1 rdy off' or 'Term2 rdy off' is displayed. (For the ready signal, see
Appendix N.)
Signal channel monitoring for command protection
In the PUP, POP or UOP schemes, when a trip permission signal is received consecutively for 10
seconds, this is considered to be an error of the signal channel and an alarm of "Ch-R1. fail"
and/or "Ch-R2. fail" is issued.
3.3.8 GPS Signal Reception Monitoring (For GPS-mode only)
If the GPS signal receiving from the GPS receiver unit is interrupted, an alarm is issued.
3.3.9 Relay Address Monitoring
In applications where the telecommunication channel can be switched, it is possible that the data
could be communicated to the wrong terminal. To avoid this, the relay address can be assigned
and monitored at each terminal to check that the data is communicated to the correct terminal.
The different address must be assigned to a relay at each terminal.
The monitoring is enabled by setting the scheme switch [RYIDSV] to "ON".
3.3.10 Disconnector Monitoring
The disconnector is monitored because the disconnector contact signal is used for the
out-of-service terminal detection and for the stub fault protection in the one-and-a-half busbar
system.
To monitor the disconnector, one pair of normally open contacts 89A and normally closed
contacts 89B are introduced. Disconnector failure is detected when both 89A and 89B are
 178 
6 F 2 S 0 8 5 0