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6.7 Maintenance
6.7.1
Regular Testing
The relay is almost completely self-supervised. The circuits that can not be supervised are binary
input and output circuits and human interfaces.
Therefore, regular testing is minimised to checking the unsupervised circuits. The test procedures
are the same as described in Sections 6.4.1, 6.4.2 and 6.4.3.
6.7.2
Failure Tracing and Repair
Failures will be detected by automatic supervision or regular testing.
When a failure is detected by supervision, a remote alarm is issued with the binary output relay of
FAIL and the failure is indicated on the front panel with LED indicators or LCD display. It is also
recorded in the alarm record.
Failures detected by supervision are traced by checking the message on the LCD "Alarm record"
screen. Table 6.7.1 shows LCD messages and failure locations.
This table shows the relationship between message displayed on the LCD and estimated failure
location. The location marked with (1) has a higher probability than the location marked with (2).
As shown in the table, some of the messages cannot identify the fault location definitely but
suggest plural possible failure locations. In these cases, the failure location is identified by
replacing the suggested failed modules with spare modules one by one or investigating and
restoring the monitored external circuits (that is CT, VT circuit, communication circuit and
isolator circuit) until the "ALARM" LED is turned off.
The replacement or investigation should be performed first for the module or circuit with higher
probability in the table.
If there is a failure and the LCD is not working such as a screen is frozen or not displayed, the
failure location is any one of SPMM and HMI module.
If no message is shown on the LCD, this means that the failure location is either in the DC power
supply circuit or in the microprocessors mounted on the SPMM module. Then check the
"ALARM" LED. If it is off, the failure is in the DC power supply circuit. In this case, check if the
correct DC voltage and polarity is applied to the relay and if the DC supply is
correct terminals
If so, replace the IO1 module mounting the DC/DC converter and confirm that the "ALARM"
LED is turned off.
In the latter case, replace the SPMM module mounting the processors and confirm that the
"ALARM" LED is turned off.
When a failure is detected during regular testing, it will not be difficult to identify the failed
module.
Note: When a failure or an abnormality is detected during the regular test, confirm the following
.
first:
- Test circuit connections are correct.
- Modules are securely inserted in position.
- Correct DC power voltage is applied.
- Correct AC inputs are applied.
- Test procedures comply with those stated in the manual.
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