Preface

The main purpose of preparing this book is to share with the readers my 15 years of experience which I have accumulated during my post doctoral research work and in the times that followed.

Attempts have been made to scrutinize each case and provide readers with detailed information and also to demonstrate applicability of the developed procedure.

The author truly hopes that in reference with the scientific reports and epidemiological studies establishing a correlation between exposure to magnetic fields and human's health, this book may be considered as a useful tool to protect health of mankind threatened by exposure to magnetic fields.

Electricity has always contributed tremendous effects on the growth of our societies as well as changing the way mankind has lived. Electricity has gone through a number of changes and has always been challenged to meet the demands. As there is nothing to produce hundred percent advantages, electricity also cannot be of exception.

Even though, in fully developed societies with switching off electricity, life comes to a complete halt, but the hazardous effects of electricity on human's health, especially those who are in direct contact with electricity or operating equipments run by electricity must be deeply investigated and steps must be taken to protect mankind against such fatal threat.

During the past decades, generation of electricity has gone through major changes and consequently, there are numerous methods to develop electricity. Irrespective of how electricity is generated, there is only one way to transport this energy, and that is through transmission line. Electrical power transmission lines are installed between the power plant and a substation. Since it is desired to deliver a large amount of power through a very long distance, transmission normally takes place at high voltage. Redundant lines are provided so that power can be routed from any power plant to any load center. The conductors, which are made of aluminum alloy and reinforced with steel strands and are not provided with insulators require minimum clearance.

When electricity entered market, it used to be delivered at the same voltage as to be used by houses and other electrical equipments, which in turn required different circuits and the distance between the power plant and the consumers was kept restricted.

In order to increase the distance between towers, which results in reducing the cost of transmission, clad steel wires and high towers are used. The number of towers per kilometer distance can be reduced to as few as 6 towers. The longest high voltage transmission line, which is installed in Republic of Congo, has a length of 1700 kilometers.

Engineers are always concerned about the power loss in transmission line. This loss, which is dissipated as heat due to the resistance, is proportional to the surface area of the transmission line conductors. Consequently, the smaller the surface area, the lower will be the loss due to heat dissipation. However, at very high voltages, corona discharge losses become very large. With high voltage transmission line, the voltage is stepped up at the generating station and then stepped down to the voltage needed by the distribution network. Such process increases the transmission efficiency.

Voltages lower than 110 KV are considered as sub-transmission voltages, whereas voltages above 230 KV are known as extra high voltage. A network of transmission lines, substations and power plants is known as transmission grid.

Due to high cost of generation of electricity, a strong possibility exists to import the required extra power in places where consumption of electricity is variable (due to hot summer and cold winter).