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# Machine riddle no.2 – 100 HZ signal producing

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• #75
Hamid

One electromotor serviceman who worked in a small workshop needed an ac power supply with 100HZ frequency.

He knew that in synchronous generator, if the magnetic flux of the field system is distributed perfectly sinusoidal around the air gap, then e.m.f generated in each full-pitched armature coil will be sinusoidal completely.
He had an old and small 50HZ generator. He decided to use it for 100HZ signal producing.
For this purpose, he changed standard distributed windings of armature that located in stator slots. Also he connected one electronically mid-pass filter which tuned with 100HZ frequency in generator output.
The output voltage of generator was not sinusoidal and it is distorted by new space flux distortion. He had a lot of harmonics in output stage of generator, but he never observed 100HZ signal in filter output.
He more and more tried and changed the stator winding distribution frequently, but he couldn't to produce purposed signal.

Why? Why couldn't he?

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• #1188
Haajee

Other than pure sine wave have harmonics; but keep in mind it depends that Even or Odd harmonics are in the distorted wave-form Square & Triangular waveforms have only one of the even or odd harmonics, I do not remember. Fourier Analysis can reveal it. So filter may pass such harmonics if those are there in the distorted waveform.

#1189
Hamid

According to electromagnetic laws, the curl of electrical field (E) must be zero, for the circulation is zero, and the curl of magnetic field (H) is not zero, however; its circulation per unit area is the current density by Ampere’s circuital law.Therefor in all magnetic systems, if some magnetic flux lines export from a surface of one volume of space, then same flux lines import to that volume via its other surfaces. It means, for mathematic function of magnetic flux we can write: f(-x) = – f(x) that named odd function. Also because of core symmetrical construction, the flux function can be written by f ( x ) = f ( L

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