Fluke 434-II User Manual page 54

Fluke 434-II/435-II/437-II
Users Manual
The Bar Graph display shows the percentage contribution of each of the components
related to the full signal. A signal without distortion should show a 1
fundamental) at 100 % while the others are at zero: in practice this will not occur because
there always is a certain amount of distortion resulting in higher harmonics.
A pure sinewave becomes distorted when higher frequency components are added to it.
Distortion is represented by the THD percentage. The display can also show the
percentage of the DC component and the K-factor. The K-factor is measurend for current
and power and displayed in the screen header. It is a number that quantifies potential
overload in transformers due to harmonic currents. Higher order harmonics influence the
K-factor more than low order harmonics.
The table below shows the number of Bar Graphs displayed simultaneously in one
screen:
All phase display
Single phase display
The left/right arrow keys are used to position the Cursor on a particular bar. The screen
header will show for that bar phase identifier, harmonic number, 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. The up/down
arrow keys are used for vertical zoom: 100 %, 50 %, 20 %, 10 %, or 5 % at full scale can
be selected.
Press in sequence: the SETUP key, F4 – MANUAL SETUP, F3 – FUNCTION PREF and
use the up/down arrow keys to select Harmonics measurement parameters and if required
adjust them with the left/right arrow keys. For detailed information see Chapter 24,
FUNCTION PREFerences.
Filtering. When measuring harmonics with interharmonics off, harmonics group is used
and a 1.5 s smoothing filter is active. When measuring harmonics with interharmonics on,
harmonics subgroup and interharmonics centered subgroup are used and no filter is
active. Refer to IEC61000-4-7 for information on grouping.
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