Power Quality Management Ltd

The BLUEWAVE active filter is here.

Harmonics...

Overview
The term ‘harmonics’ is broadly used as a reference to describe electrical distortion but, as a subject, is not yet widely understood within industry. Harmonic related problems have only become a real problem since the proliferation of semiconductors; they cause a variety of symptoms that are difficult to attribute and eliminate.
Loads drawing their current through semiconductors have a ‘non-linear’ characteristic and are primarily responsible for generating the harmonic distortion that is so damaging to supplies, equipment and sub-components.

What examples of loads are non-linear?
Single phase – PCs, monitors, photo-copiers, fax machines, high-frequency lighting, switch-mode power supplies, anything electronic in fact.
Three phase – Variable-speed drives, Uninterruptable Power Supplies, 3 phase rectifiers.

Why are harmonics a problem?
Harmonic Current - causes overheating of conductors and their insulation, overheated transformers and increased losses, overloaded Neutral conductors, Neutral to Earth potential, overheating of capacitors and, ultimately, premature ageing or failure of equipment. Additionally, exporting excessive harmonic distortion to the supply networks may well fall foul of the enforced requirements of G5/4-1.

Harmonic Voltage - causes linear loads to draw non-linear current (resulting in current distortion effects), torque pulsation in motors, capacitor dielectric failure, insulation breakdown, PC monitor and power supply failure, electronic lighting failure, malfunction of sensitive electronic equipment and, again, excessive distortion in distribution supply networks.

Deciding how to deal with harmonics
The assessment of an installation's harmonic profile, and any solution selection process, requires great care and full knowledge of the many variables (and the present regulations) that impact on Power Quality. The application of active filters and passive filters also requires an exacting approach.
Our many years of experience allows us to guarantee that the correct solution is properly implemented - we also carry out ‘before' and 'after’ measurements to prove success.