Liberty 100 Smart Electricity Meter Technical Reference Manual
5.4 Time Keeping
Liberty 100 clock maintains time in hours, minutes, and seconds format.
All data logging (e.g. load survey data, events data, maximum demands and snapshots) and scheduled task
activation (e.g. rate register switching, Friendly Credit timing, standing charge deduction etc.) take place using
the standard time whereas tariff operations and displayed date and time use local time (i.e. standard time + DST
offset). Tariff and rate registers can be configured to use standard time or local time.
When the meter’s time is invalid for any reasons an RTC failure event is logged and an alert is sent to the HES
(if configured). The following activities that rely on meter time for their correct operation are affected or
suspended:
• Rate Register switching (the meter continues with the last active rate price)
• Maximum demand updates
• Scheduled billing actions
• Delayed or scheduled meter configurations
• DST activation or deactivation
• Standing charge deduction for missing days
• Load survey operation
• Events logging will be as per the meter’s current time
• The date and time on the meter display will appear as ‘--------‘
• Midnight snapshots will be taken with standard time
The following two methods can be used to adjust a meter’s invalid time:
● Time setting from the HES
● Time synchronisation from the hub
In order to distinguish time set events between time synchronisation from the hub and time setting from HES,
the issuer ID in the case of time synchronisation is logged as ‘0’ which is the same as at manufacturing.
5.4.1 Setting Time from the HES
Meter time can be set forward or backward to an absolute value via an authenticated command from HES. In
the case of forward time setting, the missing SIP values for load profile and voltage profile are initialised with
‘FFFFFF’ which is an invalid SIP and is similar to those for power off. In the case of backward time setting, the
meter treats it as extended SIP and will cancel all upcoming SIP data whether it is on the current day or outside
the current day and will log new SIP data as normal.
5.4.2 Synchronising Time from the Hub
The meter time synchronisation sent from the communication hub via time synchronisation command will take
place only when the time drift, i.e. the time difference between the meter time and the hub time is between a
minimum (3 seconds) and maximum (50 seconds) time synchronisation thresholds. The time synchronisation is
always implemented within a demand or survey integration period boundary (whichever is less) and so the
adjustment is delayed until the next DIP or SIP.
When the time drift is less than the minimum time synchronisation threshold the meter will accept the time
synchronisation request but will not implement the change.
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