Metrology LED indicators
Visible metrology pulses proportional to active and reactive energy consumption are provided via two red LED
indicators. These indicators flash in accordance with the metrological constant marked on the front of the meter
(imp/kWh or imp/kvarh).
The metrology LED outputs comply with IEC 62053-21 and are used for metrological verification and meter
accuracy testing.
7.3. Power supplies
Power for the meter's internal electronics is provided by a three-phase switched-mode PSU, supplied from the
measured distribution-network voltages. To maintain meter accuracy in both 3 and 4 wire configurations, the
power supply can tolerate any of the following network failure conditions:
4 wire systems
missing one or two phases
missing neutral or neutral and one phase
inversion of one phase and neutral
3 wire systems
missing one phase
The power supply has enough reserve energy to withstand three-phase power outages up to 0.5 seconds.
On power-down, the unit unconditionally maintains sufficient energy for all critical data to be saved to non-volatile
memory.
7.4. Power-fail operation
In the event of a continuous absence of power, all ACE6000 meter data is saved in a non-volatile memory, with a
retention time of at least 10 years without the aid of any backup power.
The contents of the non-volatile memory are regularly checked with checksum markers and a fatal alarm (page
56) is raised if data corruption is detected.
7.5. Real-time clock
The meter incorporates a Real-Time Clock (RTC) to facilitate time- and date-based energy rate switching,
interval measurement and time stamping of events.
The RTC can be configured to use either the mains supply or an integral quartz crystal as its default frequency
reference. Where the mains supply is used, the RTC will automatically be maintained during periods of power
failure by the quartz crystal powered from the meter's lithium battery or super-capacitor.
The quartz crystal is temperature-compensated to ensure accuracy over the operating range of the meter.
The meter can also be configured to synchronise the RTC against an externally-sourced control I/O signal, either
every hour or once a day.
The RTC meets the requirements for IEC 62052-21 and IEC 62054-21 time-switches for metering.
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