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9. MAINTENANCE
/MELSEC
9. MAINTENANCE
9.1 Battery Life
When the battery voltage drops, the error indicator on the front of
the AD51 displays "00". The error can also be read using the SIR
system subroutine.
After this error message is displayed the battery has a further life of
65 days (1 560 hours).
(
Value
(
Actual Operation Period
IAv.1
1
I
Back-up by battery
1
130
days
13120
hours)
1
300days 17200
hours1
I
I
Back-up
after battery error
1
65 davr 11560
hours)
I
-
I
(
Back-up by capacitor
1
11 minutes
1
25
minutes
I
Preventitive maintenance guide.
(1) Change the battery after four years i f the total battery back-up
time during that period has been a maximum of 130 days.
(2) For back-up periods exceeding a total of 130 days in four years,
calculate the battery life as follows:
j
Assume that the power is off for 14 hours 5 days a week, and
j
all day for the remaining 2 days per week. Under these condi-
:
tions, the power is off for:
14(hours) x 5(days)
=
70 hours
24(hours) x 2(days)
=
48
hours
11
8
hours per week
j
The total battery life is 3120 hours which a t 118 hours per
i
week gives
3120
=
26.4
weeks
118
=
Approx. 6 months.
:
Therefore,
it is necessary to change the battery every 6 months.
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