126
1MRS751802-MUM
Protection Relay
Technical Reference Manual, Standard Configurations
REX 521
Distortion measurement does not include rapidly changing harmonics,
interharmonics or other spurious components.
Fig. 7.5.2.-1
Function block symbol of PQ 3Unf
Voltage waveform distortion measurement, PQ 3Unf
The voltage waveform distortion measurement PQ 3Unf is used for measurement and statistical
analysis of voltage waveform distortion. The standards concerning voltage distortion measurement are
applied to current distortion measurement in PQ 3 Unf. 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 voltage or phase-to-phase voltage or most distorted
voltage can be tracked.
Measuring modes
Not in use, L1, L2, L3, Worst phase, L1-L2, L2-L3, L3-L1
Worst main
Measurement activation
Triggering by: setting parameter, binary input, date & time
setting
Triggering mode
Single, Continuous, Periodic
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... 120.0%
0.0... 120.0% Un
0.0... 120.0% Un
Statistics
Observation times for statistics
1 hour; 12 hours; 1 day; 2 days; 3 days; 4 days; 5 days;
6 days; 1 week
Percentile setting
90.0... 99.5%
Percentiles for each harmonic and THD
0.0... 120.0% Un
Five fixed percentiles (1,5,50,95,99) for one
selectable harmonic or THD
0.0... 120.0% Un
Maximum values for each harmonic and
THD
0.0... 120.0% Un
Recorded data
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
0.1... 30.0%
0.0... 20.0% Un
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)
≥
70% Un
Measurement accuracy
Measured harmonic Im = 1st,..., 10th
Measured harmonic Im = 11th,..., 13th
In accordance with IEC 61000-4-7
±
0.3% Un, if Um < 3% Un;
±
10% Un, if Um
≥
3% Un
TRIGG
RESET
HAR_HIGH
CUM_HIGH
PQ 3Unf
Summary of Contents for REX 521
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