4.1.1. Synchronous generator
A sine-shaped alternating voltage can be generated very simply by utilising the arrangement set out in Figure 30 by means of the induction effect (U0 = c • Φ • n)
The sine-shaped voltage is attained through a conductor loop in the parallel homogeneous magnetic field. The conductor loop ends are connected to the slip ring and the voltage is fed to the operating means by carbon brushes.
1 Current direction
The same effect is produced if a stationary induction coil is shifted to within the sphere of a rotating magnet.
The voltage induction in the synchronous generator can be attained by the generation of a magnetic flow in
Every rotation of the conductor loop induces a period of alternating voltage. Where the rotation ensues within a second there is one period per second, that is to say, a frequency of one Hz. Given n rotations per minute, that is to say n/60 rotations per second, there is initially a frequency of
This equation, moreover, shows that proportionality prevails between the frequency of the generated voltage and the speed. This explains the name “synchronous generator”.
Where a four-pole arrangement (two north poles along with two south poles) is employed, there arises a period of alternating voltage in the event of a semi-rotation of the magnets.
The following then applies:
p = pole pair number
Thus, the greatest speed at which f = 50 Hz is therefore n = 3000 rpm (p = 1).
Figure 33 initially depicts the basic arrangement of a two phase alternating voltage generator.
1 Casing, 2 Stator, 3 Field spider, 4 Beginning winding one, 5 End winding one, 6 Beginning winding two, 7 End winding two
Two coils (resp. four half coils) are positioned spatially within 90 degrees on the circumference of a common stator ferromagnetic circuit.
By means of a rotating electromagnet (field spider) out-phased voltages of like amplitude and frequency are induced temporally within 90 degrees in these windings. These can be dropped off directly at the windings.
1 Voltage, 2 Winding voltage, 3 Voltage of winding two
Where three coils are shifted spatially within 120 degrees in an alternating voltage generator and distributed within the range of a common stator circuit, a rotating (electro)magnet induces three displaced voltages temporally within 120 degrees.
1.1. Winding one beginning
1 Winding one voltage, 2 Winding two voltage, 3 Winding three voltage, 4 Voltage
This principle was first cited in 1885 by Ferraris. (Galileo Ferraris, 1847-1897, Italian physicist and electrical engineer).
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