title “Problems in Alternating Current Machinery” by Professor. W. W. Lyon. These problems were compiled by Professor Lyon for use in connection with the. Theory of alternating current machinery by Alexander Langsdorf · Theory of alternating current machinery. by Alexander Langsdorf. Print book. English. Where can I get the PDF version of Langsdorf's Alternating Current Machinery book? Where can I download free PDF format novels? How do I download Hussain Zaidi's books in PDF format?.

Theory Of Alternating Current Machinery Pdf

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S. Langsdorf - Download as PDF File .pdf), Text File .txt) or read online. good bok. Title: Theory of Alternating Current Machinery Author: A. S. Langsdorf. Theory of Alternating Current Machinery by Alexander S. Langsdorf, , available at Book Depository with free delivery. PRINCIPLES OF ALTERNATING CURRENT MACHINERY - Pages · · (zlibraryexau2g3p_onion).pdf Seven naslovi Seven naslovi.

That's the essence of the simple DC electric motor, which was conceived in the s by Michael Faraday and turned into a practical invention about a decade later by William Sturgeon. You'll find more detail in our introductory article on electric motors. Before we move on to AC motors, let's quickly summarize what's going on here.

In a DC motor, the magnet and its magnetic field is fixed in place and forms the outside, static part of the motor the stator , while a coil of wire carrying the electric current forms the rotating part of the motor the rotor. The magnetic field comes from the stator, which is a permanent magnet, while you feed the electric power to the coil that makes up the rotor.

The interaction between the permanent magnetic field of the stator and the temporary magnetic field produced by the rotor is what makes the motor spin.

How does an AC motor work? Unlike toys and flashlights, most homes, offices, factories, and other buildings aren't powered by little batteries: they're not supplied with DC current, but with alternating current AC , which reverses its direction about 50 times per second with a frequency of 50 Hz.

If you want to run a motor from your household AC electricity supply, instead of from a DC battery, you need a different design of motor.

In an AC motor, there's a ring of electromagnets arranged around the outside making up the stator , which are designed to produce a rotating magnetic field.

Inside the stator, there's a solid metal axle, a loop of wire, a coil, a squirrel cage made of metal bars and interconnections like the rotating cages people sometimes get to amuse pet mice , or some other freely rotating metal part that can conduct electricity. Unlike in a DC motor, where you send power to the inner rotor, in an AC motor you send power to the outer coils that make up the stator. The coils are energized in pairs, in sequence, producing a magnetic field that rotates around the outside of the motor.


Photo: The stator makes a magnetic field using tightly wound coils of copper wire, which are known as the windings. When an electric motor wears out, or burns out, one option is to replace it with another motor. Sometimes it's easier to replace the motor windings with new wire—a skilled job called rewinding, which is what is happening here. How does this rotating field make the motor move? Remember that the rotor, suspended inside the magnetic field, is an electrical conductor.

The magnetic field is constantly changing because it's rotating so, according to the laws of electromagnetism Faraday's law , to be precise , the magnetic field produces or induces, to use Faraday's own term an electric current inside the rotor.

If the conductor is a ring or a wire, the current flows around it in a loop.

Alternating Current (AC) vs. Direct Current (DC)

If the conductor is simply a solid piece of metal, eddy currents swirl around it instead. Either way, the induced current produces its own magnetic field and, according to another law of electromagnetism Lenz's law tries to stop whatever it is that causes it—the rotating magnetic field—by rotating as well.

You can think of the rotor frantically trying to "catch up" with the rotating magnetic field in an effort to eliminate the difference in motion between them. Electromagnetic induction is the key to why a motor like this spins—and that's why it's called an induction motor.

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How does an AC induction motor work? Here's a little animation to summarize things and hopefully make it all clear: Two pairs of electromagnet coils, shown here in red and blue, are energized in turn by an AC supply not shown, but coming in to the leads on the right.

The two red coils are wired in series and energized together and the two blue coils are wired the same way. Since it's AC, the current in each coil doesn't switch on and off abruptly as this animation suggests , but rises and falls smoothly in the shape of a sine wave: when the red coils are at their most active, the blue coils are completely inactive, and vice-versa.

As the coils are energized, the magnetic field they produce between them induces an electric current in the rotor. This current produces its own magnetic field that tries to oppose the thing that caused it the magnetic field from the outer coils. Another way in which electrical energy might be transferred to a flame plasma is via resonance coupling in a microwave cavity.

Rado [3] observed in a reciprocating engine several frequencies, in the range 8 - 1 2 GHz, at which energy could be coupled into the engine resonantly. Combustion chamber dimensions correspond to electromagnetic wavelengths in the microwave spectrum, and hence standing electromagnetic waves can be maintained within such chambers.

In reciprocating engine cylinders those microwave modes that depend upon the diameter, rather than on the height should be excited. The present paper does not deal with arc discharges and the high rates of localized heating associated with them.

Such discharges, however, can be made to produce a more uniform heating by the use of a magnetic field to rotate the arc at high angular velocity [8]. FIELDS Provided that the frequency of collisions of the charged particles is much greater than that of the field, charged particles gain energy from the field and transfer it to neutral species by collision.

Electrons are more than three orders of magnitude lighter than the neutrals and energy transfer from the former via elastic collisions is very inefficient.

Alternating Current (AC) vs. Direct Current (DC)

The bulk of the transfer is via inelastic collisions [6]. On the other hand, because ions have almost the same mass as the neutrals, ionic energy transfer by elastic collisions is much more efficient and the bulk of the energy that ions gain from the field is transferred to neutrals in this way.

However, because of the much higher drift velocity of electrons, compared with that of ions, more energy is transferred to the gas through electrons than through ions for equal concentrations.

When the field frequency is much greater than the collision frequency of the charged particles, the particles are unable to oscillate in phase with the field and hence receive no energy from it. Because the collision frequency of electrons with neutrals is greater than that of ions, there must be a regime of frequency in which electrons gain energy from the field but ions do not.

Electron-gas energy exchanges for combustion gases in a. Select All Clear All Save to: Your list has reached the maximum number of items. Please create a new list with a new name; move some items to a new or existing list; or delete some items.

Theory of alternating current machinery. Theory of alternating-current machinery. Home About Help Search. All rights reserved.

Privacy Policy Terms and Conditions. Remember me on this computer. Cancel Forgot your password? Showing all editions for 'Theory of alternating current machinery'.The General Equations of A. Synchronous motors are valued in any case because their power factor is much better than that of induction motors, making them preferred for very high power applications.

This temporary field repels the original field from the permanent magnet, causing the wire to flip over.

Huge numbers of three phase synchronous motors are now fitted to electric cars. The present paper does not deal with arc discharges and the high rates of localized heating associated with them. Artwork: Electric motors are extremely efficient, typically converting about 85 percent of the incoming electrical energy into useful, outgoing mechanical work.

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