Cover Image
close this bookIntroduction to Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 213 p.)
View the document(introduction...)
View the documentPreface
View the document1. Importance of Electrical Engineering
close this folder2. Fundamental Quantities of Electrical Engineering
View the document2.1. Current
View the document2.2. Voltage
View the document2.3. Resistance and Conductance
close this folder3. Electric Circuits
View the document3.1. Basic Circuit
View the document3.2. Ohm’s Law
close this folder3.3. Branched and Unbranched Circuits
View the document3.3.1. Branched Circuits
View the document3.3.2. Unbranched Circuits
View the document3.3.3. Meshed Circuits
close this folder4. Electrical Energy
View the document4.1. Energy and Power
View the document4.2. Efficiency
View the document4.3. Conversion of Electrical Energy into Heat
View the document4.4. Conversion of Electrical Energy into Mechanical Energy
close this folder4.5. Conversion of Electrical Energy into Light
View the document4.5.1. Fundamentals of Illumination Engineering
View the document4.5.2. Light Sources
View the document4.5.3. Illuminating Engineering
View the document4.6. Conversion of Electrical Energy into Chemical Energy and Chemical Energy into Electrical Energy
close this folder5. Magnetic Field
View the document5.1. Magnetic Phenomena
View the document5.2. Force Actions in a Magnetic Field
close this folder5.3. Electromagnetic Induction
View the document5.3.1. The General Law of Induction
View the document5.3.2. Utilisation of the Phenomena of Induction
View the document5.3.3. Inductance
close this folder6. Electrical Field
View the document6.1. Electrical Phenomena in Non-conductors
close this folder6.2. Capacity
View the document6.2.1. Capacity and Capacitor
View the document6.2.2. Behaviour of a Capacitor in a Direct Current Circuit
View the document6.2.3. Types of Capacitors
close this folder7. Alternating Current
View the document7.1. Importance and Advantages of Alternating Current
View the document7.2. Characteristics of Alternating Current
View the document7.3. Resistances in an Alternating Current Circuit
View the document7.4. Power of Alternating Current
close this folder8. Three-phase Current
View the document8.1. Generation of Three-phase Current
View the document8.2. The Rotating Field
View the document8.3. Interlinking of the Three-phase Current
View the document8.4. Power of Three-phase Current
close this folder9. Protective Measures in Electrical Installations
View the document9.1. Danger to Man by Electric Shock
close this folder9.2. Measures for the Protection of Man from Electric Shock
View the document9.2.1. Protective Insulation
View the document9.2.2. Extra-low Protective Voltage
View the document9.2.3. Protective Isolation
View the document9.2.4. Protective Wire System
View the document9.2.5. Protective Earthing
View the document9.2.6. Connection to the Neutral
View the document9.2.7. Fault-current Protection
View the document9.3. Checking the Protective Measures

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

Section

Examples

Section

Examples

Generation of electrical energy Transmission of electrical energy

Power stations Overhead lines, cables

Communication-engineering

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

accumulators

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.