MCS301 - 3ph meter Page 47 of 142
MCS301 meter - product Manual 1.25 MetCom Solutions GmbH
10.4 Real time clock
10.4.1 General characteristics of the real time clock
The real-time clock of the MCS301 has the following characteristics:
• The time basis is derived from the internal oscillator with an accuracy of <5ppm
• The energy for the running reserve is supplied by an internal battery (about 10 years
backup time).
• After the running reserve has been exhausted, the device clock will start after power
up with the time and date information of the last power outage. An appropriate error
message will be created.
• The real-time clock supplies the time stamp for all events inside the meter, such as
time stamp for maximum measurement, time stamp for voltage interruptions, etc.
• If the real-time clock stops running the meter can be set to a predefined tariff.
10.4.2 Battery backup
10.4.2.1 Internal battery
To keep the RTC of the meter running the MCS301 can is equipped with an onboard,
soldered battery, which is located on the PCB under the main cover of the meter.
The features of the battery are:
• Nominal voltage /capacity 3,0V / 0,23Ah
• Life time: >15 years (normal conditions)
• Back up time for RTC: >10 years (normal conditions)
10.4.2.2 External battery
As a further option the meter can be equipped with an external, replaceable battery which is
located on the right end of the terminal block. With this external battery the RTC running and
readout without power feature works as listed below:
- internal supercap: keeps RTC running during power outage: about 2 days
- internal battery: keeps RTC running during power outage: >2 days (up to 10 years)
- external battery: support of readout without power, keeps RTC running in case the
supercap and the internal battery is empty.
Figure 16: Location of the exchangeable battery
The battery is placed under the sealed cover, which allows the access to the demand reset
push button as well as the CT/VT label.
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