Mitsubishi Melsec-A Series User Manual page 154

9.
MAINTENANCE
/MELSEC
9.2 Battery Change
9.2.1 Battery chmge frequency
When the data backup battery voltage drops, the LED on the AD71
front panel is lit and an input signal (battery error) to the PC CPU is
enabled. The battery is live for about one month more and, if it is
not replaced, data will then be lost or corrupted.
Guide for preventive maintenance
1) The battery should be replaced every 4 to
5
years if it is only
used for memory back up
for a maximum of 300 days in that
period.
2)
Battery changing frequency for memory backup duty exceeding
300
days can be calculated as follows.
Assume that there are five operation days (IO-hour operation
and 14-hour power-off during
a
day) and two power-off days
in a week. Under these conditions, power-off period during
one week is:
14 (hours) x 5 (days) = 70 hours
24 (hours) x 2 (days) = 48 hours
7200 (hours)
/
(70+48) (hours) = 61 (weeks)
61 (weeks) x 7 (days) = 427 (days)
Regarding one month as
30
days,
427 (days)
/
30
(days) = 14.2 months
Hence,
I
it is necessary to change the battery every 14 months.
9-2
IB INN
€6101-A