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close this bookIntroduction to Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 213 p.)
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View the documentPreface
View the document1. Importance of Electrical Engineering
Open this folder and view contents2. Fundamental Quantities of Electrical Engineering
Open this folder and view contents3. Electric Circuits
Open this folder and view contents4. Electrical Energy
Open this folder and view contents5. Magnetic Field
Open this folder and view contents6. Electrical Field
Open this folder and view contents7. Alternating Current
Open this folder and view contents8. Three-phase Current
Open this folder and view contents9. Protective Measures in Electrical Installations

1. Importance of Electrical Engineering

Our life would be unthinkable without the use of electrical energy. The growing utilisation of the latter is a decisive prerequisite for a rapid development of industry and agriculture.

A few examples will show the importance of electrical energy. Thus, electrical lighting is indispensable for working during the dark hours of the day. With increasing industrialisation, a growing proportion of electrical energy is used for the lighting of shops, offices, dwellings and for outdoor lighting. Man is relieved from heavy physical labour by the use of electrical devices. The drive of machines, hoisting gear and lifts is enabled in a simple form by the electromotor which in railway transport also has the advantage over internal combustion engines. There are many buildings where an air-conditioning system including heating, cooling and ventilation is installed for the operation of which electrical energy is required. At higher ambient temperatures, foodstuffs can only be kept for a prolonged period of time in refrigerators or cold-storage rooms which usually are also operated with electrical energy.

Without electrical energy, there would be no broadcasting and television systems, no telephone communication or telegraphy. In order to arrange automatic sequences of operation in production, devices of control an regulation engineering are required which, today, are driven almost exclusively by electrical energy. Table 1.1. shows a survey of the two large fields of electrical engineering, power electrical engineering and information electrical engineering.

The consumption of electrical energy by the various branches of economy is quite different. The chemical industry and metallurgy have a particularly high consumption. For the production of the electrical conductor materials electrolytic copper and aluminium, very large amounts of electrical energy are required.

Table 1.1. Sections of Electrical Engineering

Power Electrical Engineering

Information Electrical Engineering





Generation of electrical energy Transmission of electrical energy

Power stations Overhead lines, cables


Broadcasting, television, other telecommunication, telephone, telegraph, telewriter

Conversion of electrical energy

Motors, light sources, thermal devices, refrigerators, galvanic stations

Control and regulation engineering

Control of air-conditioning plants, control and regulation of production processes

Storage of electrical energy


Electronic computer engineering

Pocket computers, data processing

In industrial countries, the consumption of electrical energy increases by 4 % to 7 % per year. For this purpose, considerable amounts of primary energy carriers such as coal, petroleum or natural gas must be provided. All over the world, a reduction of the resources of primary energy carriers takes place. At the same time, their prices have been increased continuously. Water power is not in all countries available to a sufficient degree.

The initial cost for the construction of a hydroelectric power station by far exceed, the initial cost of a thermal power station.

According to the present developmental stage of engineering, nuclear power stations represent not yet a final solution of the problem. Therefore, it is absolutely necessary to use electrical energy sparingly. This also means that such devices and installations have to be developed and used which ensure a high net efficiency with as small a consumption of electrical energy as possible.

Finally, mention should be made of the fact that electrical energy can be transported conveniently through large distances at low losses. On the other hand, there is the disadvantage that electrical energy can be stored only in small amounts at high cost. Production and consumption must take place largely at the same time.