SATEC EM920 Operation Manual - Manual (Page 216)

Appendix F EN50160 Evaluation and Recording
216 EM920 Power Quality and Revenue Meter
clears the evaluation registers and counters so that each
evaluation period’s statistics is stored in a separate record.
You can upload and view the online statistics data via PAS
reports, using data collected since the beginning of the
present evaluation interval. You can also manually clear the
present contents of the counters though PAS before starting
your EN50160 evaluation.
Observation Period
The observation period is the period of time within which the
voltage characteristics shall be assessed to ensure
compliance with the standard. The observation periods
declared by the EN50160 may differ for characteristics for
which compliance limits are specified in the standard, usually
one week, and for those for which only indicative values are
provided, usually one year.
The EN50160 compliance reports produced by PAS provide
correct weekly and yearly observation statistics regardless of
the evaluation periods used for collecting data. Whenever
needed, PAS will aggregate records within a number of the
evaluation intervals to provide correct observation periods.
Some of the characteristics, like rapid voltage changes or
mains signaling voltage, may require daily assessments. If
you intend to use daily-evaluated voltage characteristics,
select the daily evaluation period via the EN50160 Advanced
setup.
Methods of Evaluation
This section describes methods used by the EM920 for
evaluating supply voltage characteristics to ensure
compliance with the standard.
Frequency Variations
Method of Evaluation
The basic frequency measurement is the mean value of the
frequency over fixed time intervals of 10 seconds under
normal operating conditions.
A frequency variation is not evaluated if the supply voltage
crosses a voltage tolerance limit (±15% Un).
Target Values
The ranges of frequency variations given in the EN50160 are:
• 50Hz±1% for 95% of a week
• 50Hz±1% for 99.5% of a year
• 50Hz+4/-6% for 100% of the time
The same limits are used for 60Hz systems. The frequency
compliance limit can be programmed in the meter in percent
of the nominal power frequency via the EN50160 PQ Recorder
setup.