Power Quality

There are two types of power factor:
- the Displacement Power Factor which is caused by inductance in an electrical load causing the consumed current to lag behind the supply voltage and
- the Harmonic Power Factor which results from non-linear switching of the supply voltage as in the case of rectifiers or power semiconductors.
Therefore the true power factor is a combination of both of these.

The subject of Power Quality has many aspects. The electricity generating and transmitting companies have a legal obligation to provide electrical power to consumers which is within specified limits for the distortion of the voltage sine-wave, variation of frequency, voltage fluctuations, sags and drop-outs. They also have to protect their own mains supply network, which includes distribution cables and transformers, from overloading caused by badly applied loads. From an...

Wind turbines are designed to produce electrical energy as cheaply as possible with maximum yield with wind speeds of around 15 metres per second (30 knots or 33 miles per hour). They have an expected oper-ating life of 20 years, which is more than 120,000 hours. In addition to achieving maximum power yield some of the important issues with wind turbines are the speed of rotation, quality of the power that is produced, protection of components, size and cost of...