Power Quality Application Guide


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European Copper Institute (ECI)

The European Copper Institute is a joint venture between ICA (International Copper Association) and IWCC
(International Wrought Copper Council) contributing members. Through its membership, ECI acts on behalf of
the world’s largest copper producers and Europe’s leading fabricators in promoting copper in Europe. Formed in
January 1996, ECI is supported by a network of ten Copper Development Associations (‘CDAs’) in Benelux, France,
Germany, Greece, Hungary, Italy, Poland, Scandinavia, Spain and the UK. It furthers the efforts initially
undertaken by the Copper Products Development Association, formed in 1959, and INCRA (International Copper
Research Association) formed in 1961.

Copper Development Association (CDA)

Copper Development Association is a non-trading organisation sponsored by the copper producers and
fabricators to encourage the use of copper and copper alloys and to promote their correct and efficient
application. Its services, which include the provision of technical advice and information, are available to those
interested in the utilisation of copper in all its aspects. The Association also provides a page link between research and
the user industries and maintains close contact with the other copper development organisations throughout the
world.

Acknowledgements

This project has been carried out with the support of the European Community and International Copper
Association, Ltd.

Disclaimer

European Copper Institute and Copper Development Association disclaim liability for any direct, indirect,
consequential or incidental damages that may result from the use of the information, or from the inability to use
the information or data contained within this publication.
Copyright© European Copper Institute and Copper Development Association.
Reproduction is authorised providing the material is unabridged and the source is acknowledged.


Switched mode power supplies (SMPS)

The majority of modern electronic units use switched mode power supplies (SMPS). These differ from older
units in that the traditional step-down transformer and rectifier is replaced by direct controlled rectification
of the supply to charge a reservoir capacitor from which the direct current for the load is derived by a method
appropriate to the output voltage and current required. The advantage – to the equipment manufacturer –
is that the size, cost and weight is significantly reduced and the power unit can be made in almost any
required form factor. The disadvantage –
to everyone else – is that, rather than
drawing continuous current from the
supply, the power supply unit draws
pulses of current which contain large
amounts of third and higher harmonics
and significant high frequency
components (see Figure 3).


Three phase loads
Variable speed controllers, UPS units and
DC converters in general are usually
based on the three-phase bridge, also
known as the six-pulse bridge because
there are six pulses per cycle (one per half
cycle per phase) on the DC output.
The six pulse bridge produces harmonics
at 6n +/- 1, i.e. at one more and one less
than each multiple of six. In theory, the
magnitude of each harmonic is the
reciprocal of the harmonic number, so
there would be 20 % fifth harmonic and
9 % eleventh harmonic, etc.