National Physical Laboratory

Harmonics & Flicker Analyser Calibrations

Harmonics & Flicker Analyser

The growth of non-linear loads on the electricity supply system has led to an increase in the current harmonics drawn from the mains. In an attempt to limit this problem, an IEC standard IEC61000-3-2 has been published that prescribes limits on the harmonics that an electrical appliance can draw from the mains supply.

In addition, the variation in current supplied to appliances connected to the electricity supply causes local voltage drops across the impedance of the mains. This can manifest itself as a flickering of the lights. The extent to which this is annoying to people is related to the magnitude of the light change and the rate at which it changes. In an attempt to reduce this phenomenon, an international standard IEC61000-3-3, imposes limits on the levels of flicker which can be induced by a given electrical appliance.

Manufacturers of electrical appliances must satisfy the requirements of both these standards in order to sell equipment in the European Union. This is usually done by carrying out a type test on the appliance in question in which the current harmonics and flicker is measured by using a 'power analyser'. Large manufacturers often purchase their own analyser to test their appliances; others may use an accredited test laboratory.

Failure to meet the harmonic or flicker standard can prevent an appliance from gaining access to important European markets. This can lead to costly redesign and delays in marketing a new product. When a product fails, particularly in 'border-line' cases, attention is drawn to the analyser. In such cases ensuring that the analyser is calibrated in a traceable manner is very important.

Download flyer outlining services available for Calibration of Harmonic & Flicker Analysers (PDF File PDF 529 KB).

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Resources

NPL Power Quality Waveform Library

Last Updated: 18 Aug 2015
Created: 8 Jun 2007

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