 | Circuits, Formulas and Tables Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 201 p.) |
 |  | (introduction...) |
| | Preface |
|  | 1. Selected Graphical Symbols of Electrotechnology |
| | 1.1. Graphical Symbols for General Circuit Elements |
| | 1.2. Graphical Symbols for Types of Current, Voltage and Connections |
| | 1.3. Graphical Symbols for Lines and Line Connections |
| | 1.4. Graphical Symbols for Resistors |
| | 1.5. Graphical Symbols for Capacitors |
| | 1.6. Graphical Symbols for Coils and Transformers |
| | 1.7. Graphical Symbols for Current and Voltage Transformers |
| | 1.8. Graphical Symbols for Electrochemical and Electrothermal Sources |
| | 1.9. Graphical Symbols for Tubes |
| | 1.10. Graphical Symbols for Semiconductors |
| | 1.11. Graphical Symbols for Switching Devices |
| | 1.12. Graphical Symbols for Machines |
| | 1.13. Graphical Symbols for Meter Movements and Measuring Instruments |
| | 1.14. Graphical Symbols of Electroacoustics |
| | 1.15. Graphical Symbols for Wiring Plans |
| | 2. Bell Circuits |
| | (introduction...) |
| | 2.1. Direct-current Bell |
| | 2.2. Alternating-current Bell |
| | 2.3. House Bell Installation |
| | 2.4. Alarm Systems |
| | 3. Basic Circuits of Illumination Engineering |
| | 3.1. Circuit-breaking Arrangements |
| | 3.2. Series Circuits |
| | 3.3. Two-way Switching Circuits |
| | 3.4. Staircase Lighting Circuits |
| | 3.5. Fluorescent Lamp Circuits |
| | 4. Electrical Machines |
| | (introduction...) |
| | 4.1. Direct-current Machines |
| | 4.1.1. Direct-current Generators |
| | 4.1.2. Direct-current Motors |
| | 4.2. Three-phase Machines |
| | 4.2.1. Three-phase Generators |
| | 4.2.2. Three-phase Motors |
| | 4.3. Transformers |
| | 4.3.1. Single-phase Transformers |
| | 4.3.2. Three-phase Transformers |
| | 5. Contactor Circuits |
| | 5.1. Types of Excitation of the Control |
| | 5.2. Possibilities of Representing Contactor Circuits |
| | 5.3. Reversing Contactor Circuits |
| | 5.4. Arc Extinguishing Circuits |
| | 5.5. Three-contactor Star-delta Connection |
| | 5.6. Squirrel-cage Induction Motor |
| | 5.7. Sliping Rotor |
| | 5.8. Interference Suppression |
| | 5.9. Light-current Controlled Power Plant with Impulse Relay |
| | 6. Rectifier Circuits |
| | 6.1. Rectifier Circuits of Alternating Current |
| | 6.2. Rectifier Circuits of Three-phase Current |
| | 7. Measurement Circuits |
| | 7.1. Measurement Circuits in Direct-current Installations |
| | 7.2. Measurement Circuits in Alternating-current Installations |
| | 7.3. Measurement Circuits in Three-phase Installations |
| | 8. Protective Circuits |
| | 9. Circuits in Motor Vehicles |
| | (introduction...) |
| | 9.1. Battery Charge |
| | 9.2. Ignition Systems |
| | 9.3. Starting Aid for Diesel Engines |
| | 9.4. Turn-signal Flasher |
| | 10. Tables |
| | 11. Basic symbols and formulas of electrical engineering |
| | (introduction...) |
| | 11.1. General direct current engineering |
| | 11.2. Magnetic field |
| | 11.3. Law of induction |
| | 11.4. Electric field |
| | 11.5. Alternating current engineering |
| | 11.6. Calculation of power |
11.1. General direct current engineering
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Ohm’s Law |
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power |
P = U2 · I |
[W] |
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P = I2 · R |
[W] |
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[W] |
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work |
W = U · I · t |
[V · A · s = Ws] |
| |
W = P · t |
[W · s = Ws] |
|
diameter of a conductor |
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[mm2] |
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resistance of a conductor |
|
[W] |
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|
[W] |
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influence of temperature on the resistance of the conductor |
RW = RK |
[1 + µ(J2 - J1)] |
Connection of resistances and power sources
· series connection
Figure
Figure
RG = R1 + R2 + R3 (total resistance)
U = U1 + U2 + U3.....
EG = E1 + E2 + E3
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condition: Ri1 = Ri2 = Ri3 |
U = I · Ra
2. Kirchhoff’s Law
The sum of all voltages around a closed path in an electrical system is zero.
The sum of the impressed voltage is equal to the sum of the voltage drops.
· parallel connection
Figure
Figure
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RE = equivalent resistance | |
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IG = total current intensity | |
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Condition: |
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Equal power sources are connected in parallel. |
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E = E1 = E2 = E3 |
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for 2 resistances connected |
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for n equal resistances |
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IG = I1 + I2 + I3 |
1. Kirchhoff’s Law
At each junction the sum of the currents flowing toward the junction is equal to the sum of the currents flowing away from the junction.
IG - I1 - I2 - I3 = 0
Figure
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