Hitachi NJI-350B Daily inspection, Items for daily inspection, Normal status Main cause of error

Chapter 15 Daily and Periodic Inspection

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	Normal status	Main cause of error
	display
Unit LED display	POW	Lighting	Power supply error, etc.
*1	RUN	Lighting	When not lit:
		(in RUN	Microcomputer malfunction, memory error, etc.
		status)	When flashing:
			Syntax error, congestion error, etc.
	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	Check operation of		Must be able to be connected online.
CPU	programming device		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	See the relay contact life
			Mechanical life	20 million times	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	Check voltage and life		Is the OK lamp flashing?
(Lithium battery)			Check to see if it has been less than
			2 months since the last exchange.
Installation and	(1)	All modules are securely	There should be no problem.		Tighten
connecting areas		fixed			Check insertion
	(2)	All connectors fit snugly			Tighten
	(3)	All screws are tightened			Visual check
	(4)	Damage and deterioration
		of each cable
Ambient environment	(1)	Temperature	0 to 55 °C		-
	(2)	Humidity	5 to 95 % RH (no condensation)
	(3)	Other	No dust, foreign matter, vibration
Spare parts	Check number of parts, storage		There should be no problem.		-
	condition
Program	Check program contents		Compare the contents of the latest		Check both master and
			program saved and CPU contents,		backup.
			and make sure they match.

(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.

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