Talk:Induction motor

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The relationship between pole pairs, frequency and speed is :- f = n*p not f = n*p/120 and also p is the number of pole pairs and not the number of poles.

I think you are using rpm and not revs/sec and you have used poles rather than pole pairs to get the 120. I think this could be a little confusing as the same variables (n and p) are used below.

[edit] Speed Control

It seams like somebody keeps wanting to incorrectly change the voltage referred to in the Speed Control section to 33V and not 25V, so I think I had better explain.

If the signal is ON for a third of the time that it is off then there are 4 quarters (3 off, 1 on) therefore the average voltage over this period will be 25V (A quarter of 100V).

This is obviously causing some confusion, if somebody thinks that the maths is wrong can they please put their thinking on here BEFORE editing the page and making it incorrect. —Preceding unsigned comment added by 194.129.210.61 (talk) 09:28, 28 September 2007 (UTC)

think speed control of ac motors, think kirloskar mysore to match your requirements —Preceding unsigned comment added by 122.167.227.169 (talk) 09:39, 14 December 2007 (UTC)

[edit] Spam

A link to electojects.com has been repeatedly added to Stepper motor, Electric motor and Brushless DC electric motor by Special:Contributions/217.53.109.235, Special:Contributions/82.201.156.201, Special:Contributions/217.53.107.168, Special:Contributions/217.53.16.164, and others.

The link in question is registered to Abdoh Ali Mohamed, Hay Swesri, Nasr City, Cairo, Egypt.[1]

I wonder if the four IP addresses listed above have any connection... Naw, couldn't be. [2][3][4][5] Egypt is a big country. Must be a coincidence.

I'm going to start patrolling wikipedia for any links to electojects.com or redirects to it and deleting them on sight. If they come back, I'll move to blacklist the address. Mdsummermsw (talk) 18:21, 28 December 2007 (UTC)

[edit] Syncronous motors WITH BRUSHES???

The article currently says 'The basic difference between an induction motor and a synchronous AC motor is that in the latter a current is supplied onto the rotor.' Really? Syncronous motors have brushes for rotor connection? The syncro motors I've disassembled look just like normal induction motors: brushless. The only difference is a magnetizable steel rotor rather than soft iron, so the rotating field becomes "frozen in" on the rotor, creating a permanent magnet. For this reason a syncro induction motor usually starts up with a random phase, since this "magnet" forms anew each time the rotor comes up to speed. --Wjbeaty (talk) 20:32, 28 February 2008 (UTC)

The magnet can be a permanent magnet (for smaller motors) or an electromagnet with brushes for larger motors. For a permanent magnet, the field doesn't get created each time. Shameer (talk) 06:06, 17 April 2008 (UTC)

you can also make a short circuit between the brushes and then have an induction motor. That was the subject of one practical work whan i was a student. we make it with some mosfet when the motor was rotating : that was fun

The difference between induction and synchronous motor come magnetic field created by the rotor : AC for induction DC for synchronous not from the presence of brushes. Yves-Laurent (talk) 19:33, 17 April 2008 (UTC)