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ION 7500 / ION 7600 User’s Guide Flicker
Power Quality: ION Meters and EN50160 Technical Note Page 307
Flicker
The flicker values Pst (short-term) and Plt (long-term) are generated according to
IEC 61000-4-15.
Observation period of one week with fixed Pst intervals of 10 minutes. A Pst
value is considered valid only if the supply voltage is within ±15% of nominal
and/or there is no voltage dip >= 15%.
N = number of Plt values collected during the observation period (based on 12
valid consecutive Pst values).
N
1
= number of intervals in which Plt > 1.
Flicker complies with the standard if N
1
/N <= 5% during the observation period (1
week by default).
NOTE
Flicker is typically caused by rapid repeated application of large loads. This causes a series of small
voltage dips which can affect the performance of nearby devices that are voltage sensitive. A voltage
flicker problem can often be observed by the naked eye by noticing flickering lights.
EN 50160 data (current observation period): The meter generates the N and N
1
counts for each phase as described above. These counters are reset at the beginning
of the next observation period.
EN 50160 data (previous observation period): The meter stores the N and N
1
counter values at the end of each observation period before these counters are
reset. These 6 registers are also stored in a data recorder for each observation
period.
Events: The meter creates a message in the Event log every time the N
1
counter for
each phase increases.
Parameter data: The meter can be enabled to record Pst and Plt values in a data
recorder at the interval used to generate these values (10 minutes and 10 x 12 = 2
hours, respectively).