Talk:Induction generator

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Self excitation of induction generators is an interesting and complex phenomenon, and should not be dismissed. Many machines will build up flux from a residual if some phase shifting system is employed, such as resonant capacitors. This can be a virtue or a problem. The process involves a transistion from synchronous operation based on residual flux and load reactance, to a chaotic establishment of slip. There is much published information on this subject.

Please add links to relevant articles, I for one would be interested. Thanks! Madhu 12:56, 21 March 2007 (UTC)

Name of this article should be changed to asynchronous generator or something similar. Any electrical generator is induction generator in principle, that is: uses electromagnetic induction to produce coil voltage. Therefore this article name is too general. --Mike1975 (talk) 19:43, 18 November 2010 (UTC)

I agree. "Asynchronous Generators," or "Induction Motors used as Generators" Jdaq (talk) 20:48, 3 February 2011 (UTC)

Google seems to suggest that 'induction generator' seems to be the standard term for this kind of generator. The general article for generators is at Electrical generator, and the specific usage of the term is clear from the introduction. The naming guidelines seems to support the current usage, since it's the most common and doesn't seem to overlap.Rememberway (talk) 21:30, 3 February 2011 (UTC)

You could add some disambiguation at the top if you want.Rememberway (talk) 21:30, 3 February 2011 (UTC)

Possible Correction to "Example Application" section

In the "Example Application" section, I disagree with the assertion for determining the frequency, as well as the fact that no information is given regarding how to regulate the output voltage.

The statement, "Prime mover speed should be used to generate frequency of 60 Hz" inherently conflicts with the statement "Required prime mover speed N = 1800 + Slip = 1840 rpm."

Instead, the capacitance should be increased or decreased to obtain the desired frequency. Also, the absolute value of the negative slip should be increased or decreased to raise or lower the output voltage respectively. For a fixed load, the voltage will be very sensitive to small changes in slip. Furthermore, the load should be limited so that the current in the windings doesn't exceed the current that would exist when operated as a motor. Jdaq (talk) 20:40, 3 February 2011 (UTC)

Varying the power factor correction capacitors to determine the frequency is a misunderstanding of their function. The excitation is not a resonant circuit with a high Q, it doesn’t set a frequency. The capacitors are used to consume leading current to neutralize the lagging current consumed magnetizing the rotor.

Diagrams showing a self-excited inductance generator attained through the use of a bank of power factor correcting capacitors are fantasies that simply don’t function. The rotor current is AC The rotor becomes demagnetized during shut-down. There is no residual magnetism to boot strap the exciter current. The diagram is from a steady state analysis of a machine started by a synchronous power source and then withdrawn. The application of this machine for an isolated power system depends on the presence of a self-excited synchronous machine for starting, and on a continuing basis to prevent the power frequency from drifting out of a safe operating range. Other means of frequency stabilization are impractical to implement at scale because of the dual need to stabilize excitation frequency and provide a variable magnitude of reactive current.

   The attractive feature of the induction generator is self-synchronization with the power system frequency and phase without tight control of the shaft speed and angle. It comes at the price of being unable to consuming lagging current and being unable to support the power grid by sourcing lagging current and requiring spinning reserve to stabilize the power system as its output varies rapidly. Adding a bank of power factor correcting capacitors corrects the power factor at a single value of excitation current. It reduces the total number of vars that have to be supplied by other machines, but the magnetizing current is variable. The most viable design for using this class of machines uses the output of the induction generator to drive a motor generator set where the generator is a conventional synchronous machine. The asynchronous inductance generator driving an m-g set is less efficient than competing designs
PolychromePlatypus (talk) 23:39, 2 August 2022 (UTC)

Synchronous speed

The sentence: Induction generators and motors produce electrical power when their rotor is turned faster than the synchronous speed. is rather incomprehensable. It suggests something like the synchronous speed is a characteristic property of an induction generator. Nijdam (talk) 10:27, 17 July 2014 (UTC)

That's probably why there's several paragraphs after that sentence. Either synchronous speed is a characteristic propery of an induction generator, or else an induction generator has no characteristic properties. --Wtshymanski (talk) 14:36, 18 July 2014 (UTC)

Your comment is no big help. Nijdam (talk) 16:35, 18 July 2014 (UTC)

So what part of the sentence give trouble? The next sentence explains typical synchronous speeds, with no more than the usual Wikibaffle. --Wtshymanski (talk) 18:03, 18 July 2014 (UTC)

Synchronous speed is Fsys/(n-poles/2), a machine dependent property. A 2 pole machine has the highest synchronous speed, 3600 RPM @ 60Hz , 3000 RPM @ 50Hz. PolychromePlatypus (talk) 20:24, 2 August 2022 (UTC)

Slip ring vs commutator

Slip ring (together with carbon brushes) provides contact from power supply to rotating rotor. On the other hand, commutator (together with carbon brushes) provides contact from power supply to the rotating and ensures current changes direction in every half cycle Yoonghm (talk) 10:21, 18 September 2017 (UTC) I reverted my changes in the article. I did not see the negative sense of the sentence. I think it should be revised.Yoonghm (talk) 10:29, 18 September 2017 (UTC)

Commutators are good than slip rings Olaosebikan Emmanuel (talk) 20:45, 31 January 2019 (UTC)

A slip ring connection has a much longer service life than a commuted connection. I’m not sure either one is relevant to a machine that uses coupled inductance to provide rotor magnetizing current and doesn’t intrinsically need a conductive rotating connection. In practice slip rings are also used to conduct stray induced currents that otherwise pass through the shaft bearings slashing their life. PolychromePlatypus (talk) 00:01, 3 August 2022 (UTC)