Switching power supplies, which are used in products such as variable frequency motor drives (VFDs), IT equipment, home entertainment systems and LED lighting tend to draw power through current spikes at the peak of the mains cycle. Low-energy compact fluorescent light bulbs (CFLs) also exhibit the same behaviour. Drawing current at the peaks causes harmonic distortion which results in power being wasted in motors and transformers. It can also cause increased noise and wear on bearings and in extreme circumstances the equipment can fail due to overheating.
Renewable energy sources such as solar cells may require conversion of DC power to AC. If the output AC waveform is an imperfect sine wave, this harmonic distortion can have a similar effect.
The Outram Ranger PM7000 is the first power quality analyser to offer analysis of the phase difference between the harmonic voltage and current, giving additional detailed information about the source of distortion of the mains waveform. Modern switching power supplies often exhibit problems at high frequencies, and so the PM7000 offers one of the industry’s highest sampling rates, recording up to the 50th or 120th harmonic.
“Visibility is critical to help engineers solve the increasing problem of harmonic distortion of the mains waveform,” said John Outram, Managing Director of Outram Research. “By providing information on the phase difference between current and voltage up to the 120th harmonic we help engineers to identify and resolve problems more quickly and efficiently.”
The new harmonic distortion analysis features are now provided as standard across the family of Outram Ranger PM7000 power analysers. New firmware to upgrade existing analysers is available on request.
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