ABB REX 521, Technical Reference Manual, Standard Configurations

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1MRS751802-MUM REX 521
125
Protection Relay
Technical Reference Manual, Standard Configurations
7.5.2. PQ 3Unf
The function block PQ 3Unf is used for measuring the harmonics and monitoring
the power quality in distribution networks. Power quality measurements carried out
by the function block PQ 3Unf follow the European Standard EN 50160. Data
collection and analysis is done according to EN 50160. Measuring principles for
individual harmonics and THD are adapted from the International standard IEC
61000-4-7. The American standard IEEE Std 1159 is also partly supported.
The function block measures quasi-stationary (slowly varying) harmonics up to
13th.
Current waveform distortion measurement, PQ 3Inf
The current waveform distortion measurement PQ 3Inf is used for measurement and statistical analysis
of current waveform distortion. The standards concerning voltage distortion measurement are applied
to current distortion measurement in PQ 3 Inf. Data collection and analysis is done according to EN
50160. Measuring principles for individual harmonics and THD are adapted from the International
standard IEC 61000-4-7. The American standard IEEE Std 1159 is also partly supported. Analysis can
be done for one selected phase current or most distorted phase current can be tracked.
Measuring modes
Measurement activation
Triggering mode
Distortion factor
Not in use; L1; L2; L3; Worst phase
Triggering by: setting parameter, binary input, date & time setting
Single; Continuous; Periodic
THD; TDD
Monitored values
THD (3 sec and 10 min mean
values)
Harmonic components from 1st to
13th (3 sec mean values)
Harmonic components from 2nd to
13th (10 min mean values)
0.0... 1000.0%
0.0... 1000.0% In
0.0... 1000.0% In
Statistics
Observation times for statistics
Percentile setting
Percentiles for each harmonic and
THD
Five fixed percentiles (1,5,50,95,99)
for one selectable harmonic or THD
Maximum values for each harmonic
and THD
Recorded data
1 hour; 12 hours; 1 day; 2 days; 3 days; 4 days; 5 days; 6 days; 1
week
90.0... 99.5%
0.0... 1000.0% In
0.0... 1000.0% In
0.0... 1000.0% In
One data set for updating; One data set from the previous
observation period
Harmonic limit supervision
Limit for THD
Limits for each harmonic
Recorded data
0.0... 60.0%
0.0... 40.0% In
If any limit should be exceeded, the whole harmonic set will be
recorded during the maximum THD (3 sec values)
Operation criteria
Fundamental frequency
Frequency deviation
Amplitude of the fundamental wave
0.9... 1.1 Fn
≤
0.5 Hz (difference between max. and min. values within one
second)
≥
1% In
Measurement accuracy
Measured harmonic Im = 1st,..., 10th
Measured harmonic Im = 11th,...,
13th
In accordance with IEC 61000-4-7
±
1.0% In, if Im < 10% In;
±
10% In, if Im
≥
10% In