The Yokogawa WT3000 digital power analyser equipped with IEC harmonics
testing software complies with the latest EN standard on harmonics testing:
EN61000-3-2:2006.
IEC Standard 61000-4-7 Ed. 2, which is now obligatory as the test method for
harmonics testing, specifies that the test instrument must be able to accept
current input signals with a crest factor (peak current divided by RMS
current) of at least 4 for inputs up to 5 A RMS, 3.5 for inputs up to 10 A
RMS and 2.5 for higher RMS currents.
Unlike other instruments, the Yokogawa WT3000 has its input current ranges
specified in RMS, and a crest factor of 3 or 6 can be selected. It therefore
more than satisfies the accuracy requirements for testing higher harmonics
according to the standard, for continuous input currents up to 33 A RMS.
The WT3000 can also carry out interharmonics testing (also required by IEC
61000-4-7 Ed2) with the sample rate controlled by a phase-locked loop
multiplying the input frequency by either 900 (for 50 Hz) or 750 (for 60
Hz). This means that the interharmonics frequencies, which occur at 5 Hz
intervals, are sampled. This so-called advanced FFT (Fast Fourier Transform)
method results in an accurate and very fast measurement of the
interharmonics.
Yokogawa has released an updated version (5.11) of its IEC compliance
software for the WT3000 which also incorporates the latest amendments to IEC
standards IEC 61000-3-2 and IEC 61000-3-12 for harmonics and IEC 61000-3-3
and IEC 61000-3-11 for flicker and voltage fluctuations.
Yokogawa
http://tmi.yokogawa.com
+31 (0) 88 464 1811
[email protected]