 | Introduction to Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 213 p.) |
 |  | (introduction...) |
| | Preface |
| | 1. Importance of Electrical Engineering |
|  | 2. Fundamental Quantities of Electrical Engineering |
| | 2.1. Current |
| | 2.2. Voltage |
| | 2.3. Resistance and Conductance |
| | 3. Electric Circuits |
| | 3.1. Basic Circuit |
| | 3.2. Ohm’s Law |
| | 3.3. Branched and Unbranched Circuits |
| | 3.3.1. Branched Circuits |
| | 3.3.2. Unbranched Circuits |
| | 3.3.3. Meshed Circuits |
| | 4. Electrical Energy |
| | 4.1. Energy and Power |
| | 4.2. Efficiency |
| | 4.3. Conversion of Electrical Energy into Heat |
| | 4.4. Conversion of Electrical Energy into Mechanical Energy |
| | 4.5. Conversion of Electrical Energy into Light |
| | 4.5.1. Fundamentals of Illumination Engineering |
| | 4.5.2. Light Sources |
| | 4.5.3. Illuminating Engineering |
| | 4.6. Conversion of Electrical Energy into Chemical Energy and Chemical Energy into Electrical Energy |
| | 5. Magnetic Field |
| | 5.1. Magnetic Phenomena |
| | 5.2. Force Actions in a Magnetic Field |
| | 5.3. Electromagnetic Induction |
| | 5.3.1. The General Law of Induction |
| | 5.3.2. Utilisation of the Phenomena of Induction |
| | 5.3.3. Inductance |
| | 6. Electrical Field |
| | 6.1. Electrical Phenomena in Non-conductors |
| | 6.2. Capacity |
| | 6.2.1. Capacity and Capacitor |
| | 6.2.2. Behaviour of a Capacitor in a Direct Current Circuit |
| | 6.2.3. Types of Capacitors |
| | 7. Alternating Current |
| | 7.1. Importance and Advantages of Alternating Current |
| | 7.2. Characteristics of Alternating Current |
| | 7.3. Resistances in an Alternating Current Circuit |
| | 7.4. Power of Alternating Current |
| | 8. Three-phase Current |
| | 8.1. Generation of Three-phase Current |
| | 8.2. The Rotating Field |
| | 8.3. Interlinking of the Three-phase Current |
| | 8.4. Power of Three-phase Current |
| | 9. Protective Measures in Electrical Installations |
| | 9.1. Danger to Man by Electric Shock |
| | 9.2. Measures for the Protection of Man from Electric Shock |
| | 9.2.1. Protective Insulation |
| | 9.2.2. Extra-low Protective Voltage |
| | 9.2.3. Protective Isolation |
| | 9.2.4. Protective Wire System |
| | 9.2.5. Protective Earthing |
| | 9.2.6. Connection to the Neutral |
| | 9.2.7. Fault-current Protection |
| | 9.3. Checking the Protective Measures |
7.1. Importance and Advantages of Alternating Current
In the preceding Sections, we have explained the electro-technical conformities with natural laws under the restricting condition that current intensity and magnitude of voltage remain constant with respect to time. In practice, however, especially in power electrical engineering, mainly alternating current is used.
Alternating current is a current whose magnitude and direction varies periodically; this also applies to alternating voltage.
The electrical laws naturally also apply to alternating current engineering; a few peculiarities have to be observed, however.
Of the various possible forms, the sinusoidal alternating current has the greatest importance. Its substantial advantages are as follows:
· simple and economical generation
· transformation into other values (principle of mutual induction)
· low-loss energy-transmission even through large distances
· the sinusoidal form is not changed by the basic components R, L and C
Because of these and other advantages, alternating current engineering is of paramount importance. If direct current is required (e.g. for the operation of the majority of electronic devices), it can easily be produced by rectifying the alternating current. In practice, especially in power electrical engineering, alternating current is used because of many advantages. This is a current whose magnitude and direction varies periodically. The sinusoidal alternating current has the greatest importance.
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