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P OWER QUA LIT Y
3.3
Power quality
3.3.1
Harmonics refers to the amount of electricity contained in the current that is an integral mul-
tiple of the fundamental (i.e., 50 Hz or 60 Hz). FC610 measures total harmonic distortions as
well as individual harmonics up to 31st harmonic.
Total Harmonics
THD of current L1
THD of current L2
THD of current L3
THD of voltage L1
THD of voltage L2
THD of voltage L3
THD of voltage U12
THD of voltage U23
THD of voltage U31
3.3.2
FC610 monitors unbalanced current and current unbalanced condition.
Unbalanced current is presented as a percentage value following below calculation and displayed di-
rectly through HMI.
max{|��
1
I
=
������
where
��
+ ��
1
2
I
=
������
3
The current unbalance threshold and hysteresis is a percentage value. A current unbalance
event is detected when current unbalance value I
when the I
nba
1T N C928 25 0M0 201
Harmonics measurement
Current unbalance supervision
− ��
|, |��
− ��
|, |��
− ��
|}
������
2
������
3
������
��
������
+ ��
3
is equal to or below the value of the threshold minus the hysteresis.
Individual Harmonic
Harmonic I1 3rd to 31st
Harmonic I2 3rd to 31st
Harmonic I3 3rd to 31st
Harmonic U1 3rd to 31st
Harmonic U2 3rd to 31st
Harmonic U3 3rd to 31st
Harmonic U12 3rd to 31st
Harmonic U23 3rd to 31st
Harmonic U31 3rd to 31st
is above the threshold. The event ends
nba
PR OD UCT FU NCTI ONS
2 1
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