**Part 4**

**Industrial Environments** 

208 Power Quality Harmonics Analysis and Real Measurements Data

Chapman, D. Rating of Transformer supplying harmonic loads. Leonardo Energy.

Bird, J. O. Electrical circuit theory and technology. Newnes, May.

Mathworks. www.mathworks.com

**9** 

M.H. Shwehdi

*Saudi Arabia* 

**Harmonics Effect in Industrial** 

**and University Environments** 

*King Faisal University, College of Engineering, Al Ahsa,* 

**1.1 Analyzing harmonic distortion produced from lead blast furnace (LBF)** 

A major cost to a steel factory facility is the energy used to power the arc furnace for the melting and refining process. Operation at low power factor results in additional voltage drop through the power system yielding a lower system voltage on the plant buses. Low system voltage increases the melt time and will add to the overall plant operating costs per ton. Low power factor can also result in additional costs in the form of penalties from the electric-utility company [1-2, 8]. Capacitor can be applied in steel factory facilities for a wide range of benefits. The capacitors will improve the power factor of the system; reduce billing penalties imposed by the electric power utility, and increase system voltage-boosting productivity. The system losses are also reduced improving the electrical system efficiency. However, harmonic sources in the steel mill can interact with capacitor banks resulting in problems if they are not properly applied. The effect of harmonics varies depending on the type of load. In some cases such as a resistance heating load all of the applied voltage does useful work; although, in most cases involving transformers and motors only the 60-Hz component of the voltage does useful work and the harmonic component generates useless heat. Sensitive electronic control circuits, timers, and logic circuits may be affected if the

The harmonic current generated by any non-linear load flows from the load into the power system. This current, seeking a low impedance path to ground, causes a voltage of the drop through the system according to Ohm's Law. The harmonic voltage combines with the 60 Hz voltages producing a distorted power system voltage. The harmonic laden power system voltage is then imposed on al1 of the remaining loads connected to the system this voltage distortion may result in more harmonic currents being produced as other linear loads

A few industries like steel mills and aluminum smelters used electricity to power arc furnaces, which distorted the waveform, because the current flow was not directly proportional to the voltage. These loads are called non-linear loads. Non-linear loads cause waveforms that are multiples of the normal 60 Hertz sine wave to be superimposed on the base waveform. These multiples are called harmonics. Harmonic is defined as a sinusoidal component of a periodic wave having a frequency that is an integral multiple of the fundamental frequency. For example, the second harmonic is a 120 Hertz waveform (2 times

**1. Introduction** 

supply voltage is distorted [3-5].

experience the distorted system voltage.

60 Hertz), the third is a 180 Hertz waveform, and so on.
