Toshiba GRZ100 B Series, Инструкция по эксплуатации, Страница: 162 / 447

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Signal channel testing
In the BOP scheme, the signal circuit including the remote end is automatically tested at a
prescribed time interval. Testing commences when a signal is transmitted from the local to remote
end. When the remote end receives the signal, it returns the signal on condition that there is no
fault on the power system. The terminal which is carrying out the testing checks that the
transmission path is healthy by receiving the return signal from the remote end within a prescribed
time after the carrier signal is transmitted from the local end.
If the signal cannot be received after the prescribed time, an alarm signal of carrier channel failure
is generated and a message " Remote 1 fail" is displayed on the LCD when manual testing.
To start the channel testing, the switch [CHMON] is set to "ON" and set the channel test interval.
The channel test interval can be set from 1 to 12 hours. And then, the OR logic output of the signal
No.225:EXT_CAR-S and the signal No.252:SBT is assigned the binary output BO13 of IO2.
Note 1
:
The time count for test interval is initialized when manual test is started or DC supply is turned on
.
Note 2: Under any of the following conditions, the signal channel test does not start.
•
BOP is not selected as the protection scheme.
•
Telecommunication equipment is out-of-service.
•
Scheme switch [CHMON] is set to "Off".
•
Undervoltage elements operate.
•
Circuit breaker is open.
3.3.5 Disconnector Monitoring
The disconnector is monitored because a disconnector contact signal is used for the stub fault
protection in a one-and-a-half circuit breaker arrangement.
To monitor the disconnector, one pair of normally open contact and normally closed contact is
introduced. Disconnector failure is detected when both contacts are simultaneously in the open or
closed state for a prescribed period.
Monitoring is blocked by setting the scheme switch [LSSV] to "OFF". Default setting of the
[LSSV] is "OFF" to prevent a false failure detection when the disconnector contacts are not
introduced.
3.3.6 Failure Alarms
When a failure is detected by the automatic supervision, it is followed with an LCD message, LED
indication, external alarm and event recording if a signal assigned. Table 3.3.6.1 summarizes the
supervision items and alarms.
The alarms are retained until the failure has recovered.
The alarms can be disabled collectively by setting the scheme switch [AMF] to "OFF". The setting
is used to block unnecessary alarms during commissioning, test or maintenance.
When the Watch Dog Timer detects that the software is not running normally, LCD display and
event recording of the failure may not function normally.