Bar Graph Screen
The Bar Graph display shows the percentage contribution of each of the components related to the
fundamental or full signal. A signal without distortion should show a 1st harmonic at 100% while the
others are at 0: in practice this will not occur because there always is a certain amount of harmonics
resulting in distortion.
A sinewave becomes distorted when harmonics components are added to it. Distortion is represented by
the Total Harmonic Distortion (THD) percentage. The display can also show the percentage of the DC
component and each harmonic ratio.
The left/right arrow keys are used to position the Cursor on particular bar. The screen header will show
for that bar phase identifier, harmonic component ratio, frequency and phase angle. If not all bars are
shown on the screen, you can bring the next set within the viewing area by moving the Cursor off the left
or right end of the screen.
Available function keys:
F1
Selection of harmonics type:
voltage, current.
F2
Selection of bar set to be displayed:
L1, L2, L3, N or all
F3
Interharmonics display on/off
F4
Open the table screen
F5
Switch between RUN and HOLD.
Table Screen
The table screen lists all the harmonic parameters, including Harmonic Voltage, Harmonic Current,
Interharmonic Voltage and Simple Harmonic Current. Select next page with up/down keys.
Available function keys:
F3
Take fundamental voltage as percentage reference (%f) or total harmonic voltage as
percentage reference (%r)
F4
Open the bar graph screen of harmonic
F5
Switch between RUN and HOLD.
Tips and Hints
The harmonic number indicates the harmonic frequency: the first harmonic is the fundamental frequency
(60 or 50Hz); the second harmonic is the component with two times the fundamental frequency (120 or
100Hz), and so on.
The harmonics sequence can be positive (1, 4, 7…), zero (3, 6, 9…) or negative (2,
5, 8…). Positive sequence harmonics try to make a motor run faster than the fundamental, negative
sequence harmonics try to make a motor run slower than the fundamental. In both cases the motor
looses torque and heats up. Harmonics can also cause transformers to overheat. Even harmonics
disappear if waveforms are symmetrical, i.e. as equally positive and negative.
Zero sequence current harmonics add in Neutral conductors. This can cause overheating of these
conductors, and make ground potential rising..
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