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Power Quality Monitoring
Introduction16
16-3
average from these measuring values across 10-minute observation periods. The 10-
minute averages are compared against the tolerance range (in this example 102 ... 138 V).
The 100 % limit means that the 10-minute averages must always (i.e. 100 % of time or
with 100 % probability) be within range. The bar graph will turn to red if a 10-minute
average crosses the tolerance range.
The adjustable limit of for instance 95 % (i.e. 95 % probability) means that 95 % of the
10-minute averages must be within tolerance. The 95 % limit is less stringent than the
100 % limit. Therefore the related tolerance range usually is tighter. For 120 V this for
instance can be + or – 10 % (a tolerance range between 108 ... 132 V).
The bars for Dips/Interruptions/Rapid Voltage Changes/Swells are narrow and indicate
the number of limits violations that occurred during the observation period. The allowed
number is adjustable (for instance to 20 Dips/week). The bar turns to red if the adjusted
limit is violated.
You can use a pre-defined set of limits or define your own. An example of a pre-defined
set is that according to the EN50160 standard. A maximum of 6 sets can be chosen: 2
factory installed sets, 2 sets only definable by the administrator via FlukeView SW43W
software, and 2 sets that can be changed on the Analyzer. Selection and definition of
limits is accessible via the SETUP key, ‘limits’ selection and then Function key F3 –
EDIT.
The table below gives a survey of the aspects of Power Quality Monitoring:
Parameter Available Bar Graphs Limits Averaging Interval
V rms 3, one for each phase Probability 100 %: upper
& lower limit
Probability x %: upper &
lower limit
10 minutes
Harmonics 3, one for each phase Probability 100 %: upper
limit
Probability x %: upper
limit
10 minutes
Flicker 3, one for each phase Probability 100 %: upper
limit
Probability x %: upper
limit
2 Hrs.
Dips/Interruptions/Rapid
Voltage Changes/Swells
4, one for each
parameter covering all 3
phases
allowed number of
events per week
½ cycle rms based
Unbalance 1, covering all 3 phases Probability 100 %: upper
limit
Probability x %: upper
limit
10 minutes
Frequency 1, covering all 3 phases
Measured on Reference
Voltage Input A/L1
* Probability 100 %:
upper & lower limit
Probability x %:
upper & lower limit
10 sec.