New requirements for harmonics analysers
THE specifications for compliant harmonics and flicker analysers are about to change with the introduction of the new IEC 61000-4-7 Ed.2 requiring that measurements are taken using two different rectangular measuring windows, each of 10 periods per window for 50Hz, and 12 periods per window for 60Hz.
No gap and no overlapping of successive windows is allowed and the rectangular windows must be accurately synchronised to the fundamental frequency.
Furthermore, the new IEC 61000-4- 7 edition 1: 1, introduces a grouping procedure for harmonics and interharmonics between two adjacent harmonics being added to the nearest harmonics as per the stipulated calculation formula.
The new IEC 61000-4-15 Edition 1:1 specifies a new flicker meter for 120V/60Hz ac supplies and also gives a more accurate description of the weighting filter design.
To meet these new requirements the EM Test DPA500, available from Consultant Technology , is based on a real-time kernel and equipped with its own hard disk, and allows the recording of measured data continuously without any gaps or overlapping and the rectangular measurement window is synchronised to each group of 10 or 12 cycles of the mains supply frequency (50Hz or 60Hz) by means of a digital PLL (Phase Lock Loop).
A wide current input range (up to 50A) avoids loss of measured data due to range switching that would occur when using different shunt resistors.
The classification of the measurement can be selected at any time, before or after the measurement has been performed and during all measurements the AC supply voltage is measured simultaneously with the current.
The built-in flicker impedance, which is automatically selected when doing flicker measurement, makes the DPA 500 a complete single-box unit for both harmonics and flicker analysis.
Powerful ISMDPA control and analysing software for harmonics, interharmonics and flicker measurement is central to the operation of the DPA500.
ISMDPA controls the upload of the recorded measuring data for the classification and analysis and it includes analysis as per the latest standards as well as procedures following the former standard requirements.
An easy Fail/Pass function allows fast analysis while detailed data is available for extended analysis and EUT evaluation purposes. ISMDPA also includes a powerful documentation capability with direct export to Word.
The EM TEST family of harmonics analysers comprises two models that cover harmonics, interharmonics and flicker for single phase and three-phase applications. The three-phase analyser DPA503 can also be used for single phase analysis applications.
13-Apr-2005