Programming The Meter; Real Time Clock And Calendar - Elster A1140 User Manual

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A1120/40 - Electronic Polyphase Meter
17

PROGRAMMING THE METER

The meter can be programmed via the optical port or via the RS232 port. The optical port can be
connected either directly to a PC (IBM compatible) or to a Hand Held Unit. In both cases an IEC
62056-21 (formerly 1107) Probe is required.
Information for the meter is first prepared on forms within the Power Master Unit Software (Refer
to Master Unit Software M181 001 3).
The meter does not check to ensure that reprogramming has been completed, therefore at the
end of a reprogramming session all data should be read back to confirm the meter is
programmed correctly.
If communications fail during programming a failure message is displayed.
Each time the meter is reprogrammed, the programming counter is incremented and the time and
date of the event is recorded. The user who created the scheme in the PMU is recorded.
Note: The programming counter does not increment when a 'Set time' or 'Time and date
adjustment' only is programmed to the meter.
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REAL TIME CLOCK AND CALENDAR

The clock uses the notation 00:00 to 23:59. The calendar automatically caters for leap years.
Note: - For time stamps 00:00 indicates the start of the day and 24:00 the end of the day.
The time base for the clock is a programmable option. It can be derived from either the a.c.
supply frequency or from a crystal controlled oscillator.
When the clock is synchronised to the mains frequency, it maintains synchronisation for
variations of up to +/- 5% of nominal mains frequency. Outside these limits the meter switches to
the crystal oscillator and then switches back to mains when the frequency is back within limits.
Crystal calibration achieves an internal accuracy of better than 0.5 of a second per day at
reference temperature. In the event of a supply failure a backup battery supports the crystal
oscillator, which maintains timekeeping.
There are two methods of adjusting the meter clock:
1. The time and date of the clock may be set via the IEC 62056-21 optical port or RS232
communications port (if fitted) provided the correct (level 2 or higher) password is used.
2. If a request for a small adjustment (-7.5 minutes to +7.5 minutes) to the current setting is
made (with appropriate password), this adjustment will be applied by shortening or
lengthening subsequent demand periods by 5 seconds until the whole of the adjustment has
been achieved.
© Elster Metering Limited - M181 001 2G - 5/2010