Hitachi NJI-350B - Manual (Page 308)

Chapter 15 Daily and Periodic Inspection
15-1
Chapter 15 Daily and Periodic Inspections
In order to use the functions of the MICRO-EH in the optimal conditions and maintain the system to operate normally, it
is essential to conduct daily and periodic inspections.
(1) Daily inspection
Verify the following items while the system is running.
Table 15.1 Items for daily inspection
Item
LED
display
Normal status Main cause of error
POW Lighting Power supply error, etc.
RUN Lighting
(in RUN
status)
When not lit:
Microcomputer malfunction, memory error, etc.
When flashing:
Syntax error, congestion error, etc.
Unit LED display
*1
OK Lighting When not lit:
Microcomputer malfunction, memory error, etc.
When flashing:
Battery error *2
*1: The MICRO-EH indicates the error contents using the combination of lit/flashing/not lit status of OK and
RUN lamps. For details, see the error code list in Chapter 12.
*2: If the power supply for the basic unit is left turned off without replacing the battery after the OK lamp was
flashing, the memory contents may be destroyed. Exercise caution when the system power is turned off for a
long period of time, since this error may not have been detected and the memory contents may have already
been destroyed.
(2) Periodic inspection
Turn off the power for the external I/O circuit and check the following items once every six months.
Table 15.2 Items for periodic inspection
Part Item Check criteria Remarks
Programming device to
CPU Check operation of
programming device Must be able to be connected online.
All switches and display lamps work
normally.
Power supply Check for voltage fluctuations 85 to 264 V AC Tester
I/O module Output relay life Electrical life 200,000 times
Mechanical life 20 million times
See the relay contact life
curve (Chapter 10).
LED Turns on/off correctly
External power voltage Within the specification for each I/O See the I/O specifications
(Chapter 6).
Battery
(Lithium battery) Check voltage and life Is the OK lamp flashing?
Check to see if it has been less than
2 months since the last exchange.
Installation and
connecting areas (1) All modules are securely
fixed
(2) All connectors fit snugly
(3) All screws are tightened
(4) Damage and deterioration
of each cable
There should be no problem. Tighten
Check insertion
Tighten
Visual check
Ambient environment (1) Temperature
(2) Humidity
(3) Other 0 to 55 °C
5 to 95 % RH (no condensation)
No dust, foreign matter, vibration
-
Spare parts Check number of parts, storage
condition There should be no problem. -
Program Check program contents Compare the contents of the latest
program saved and CPU contents,
and make sure they match. Check both master and
backup.
(3) Life of the power module
Numbers of electrolytic condensers are used in the power module. Electrolytic condensers have a lifetime and it is
believed that the life is reduced by half when the ambient temperature rises 10
°C.
When stocking spare parts, the standard for consideration is that the power module has a life of approximately five
years when used at the rated ambient temperature (30
°C). Also, to extend the life of the module, consider the air
circulation around the module and ambient temperature when installing it.