IDEC SmartRelay functions
IDEC SmartRelay Manual 123
Accuracy of T
Because of slight tolerances in the characteristics of
electronic components, the set time T may deviate. You can
find a detailed description of such deviations in the "On-
delay" topic (Page 131).
Accuracy of the timer (Seven-d
ay/Twelve-mont
h time switch)
To prevent timing inaccuracy of the real-time clock in C
versio
ns caused by this deviation, the timer value is
continuously compared with a high-precision timebase and
corrected. The resultant maximum timing inaccuracy is ±5
s/day.
4.3.3 Backup of the real-time clock
Because the internal real-time clock of an IDEC SmartRelay
is backed up, it continues operation after a power failure.
The ambient temperature influences the backup time. At an
ambient temp
erature of 25°C, the typical backup time is 80
hours.
If there is a power outage of an IDEC SmartRel
ay for more
than 80 hours, the internal clock responds, as shown below:
On restarting, the clock is set to "Sunday 00:00 1 January". The
time is stopped and flashe
s. IDEC SmartRelay is back in the
status that it was in before the power outage. In the RUN status,
the system processes the counters that were parameterized
with the time above. The clock is, however, still stopped.
• Equipment series FL1E:
If you are using the optional IDEC SmartRelay Battery
ca
rtri
dge, or combined IDEC SmartRelay Memory/
Battery cartridge, IDEC SmartRelay can retain the clock
time for up to two years. These cartridges are available
for equipment series FL1E. To backup the real time clock
for more than 80 hours, insert a battery cartridge or a
combined memory/battery cartridge to the base module.
4.3.4 Retentivity
The switching states, counter and time values of many SFs
can be set retentive. This means that current data are
retained after a power failure, and that the block resumes
operation at the break point. The timer is not reset, but
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