SATEC EM920 Operation Manual - Manual (Page 218)

Appendix F EN50160 Evaluation and Recording
218 EM920 Power Quality and Revenue Meter
the supply voltage. Flicker is indicated by the long-term
flicker severity parameter Plt, which is evaluated every 2
hours.
Method of Evaluation
The basic measurement is the short-term flicker severity
indicator Pst, evaluated each 10 minutes by instrumentation
complying with IEC 61000-4-15. The indicative long-term
flicker severity Plt is evaluated from 12 consecutive Pst
values. For testing purposes, the Pst period can be
temporarily changed in the meter in the range of 1 to 10
minutes via the EN50160 Advanced Setup.
Pst values are not classified during intervals when the supply
voltage magnitude exceeds a voltage tolerance limit (±15%
Un) or is affected by voltage dips with depth more than 15%
Un.
Target Values
The flicker compliance limit given in the EN50160 is:
Plt ≤ 1 for 95% of a week
The Plt compliance limit can be changed in the meter via the
EN50160 PQ Recorder setup.
Voltage Dips
A voltage dip is a sudden reduction of the RMS voltage below
90% of the nominal value, followed by a return to a value
higher than 90% of the nominal in a time varying from 10 ms
to 60 s.
Method of Evaluation
A voltage dip is classified as one polyphase event regardless
of the shape and of the number of phases affected (as per
Eurelectric’s Application guide to the European Standard EN
50160, and IEC 61000-4-30). An event can begin on one
phase and end on another phase. The fault magnitude is
recorded separately for each phase involved. The event
duration is measured from the instant at which the voltage
falls below the start threshold on one of the phases to that at
which it becomes greater than the end threshold on all
affected phases including a threshold hysteresis.
The basic voltage dip measurement is one-cycle RMS voltage
updated each half-cycle.
The voltage dip threshold can be changed in the meter via
the EN50160 PQ Recorder setup.
Statistical Results
The EM920 provides the statistical evaluation of voltage dips
using the classification established by UNIPEDE. Dips are
classified by residual voltage magnitude and duration as
shown in Appendix E.