Topics: Fully Pitched Winding
on General Discussion
Fully Pitched Winding
I have heard that "Fully Pitched Winding" is recent advancement in Machine design. Can anybody explain me its working and its advantage?
09-19-2013 06:20 AM
This topic is really interesting can anybody comment ?
09-19-2013 08:31 AM
Full pitch winding machines are not recent. In fact they are known from many, many years ago.
There is an excellent book dealing with this issue, may be you can buy it in internet.
"Handbook of electric motors", by Hamid A. Toliyat and Gerald B. Kliman, edited by Taylor and Francis Group., check at chapter 4.
09-19-2013 10:50 AM
Contact Motor/Alternator manufacturers regarding fractional & full pitch windings * why they are used,advantages,disadvantages etc
09-19-2013 01:05 PM
A "full pitch winding" in the design of the alternator means that the stator windings span all of the slots in each phase. Most alternators are not full pitch machines, because while the design results in the lowest cost machine, it also will generally not have the best waveform shape. (in other words, greater harmonic content, particularly 3rd order content).
This is a bit hard to visualize, but you can find a simple explanation and illustrations in the following manual:
Full pitch alternators have been around since alternators were invented...some day I need to look up how long ago that was...way older than me, for sure.
09-19-2013 03:38 PM
Gary, using a full pitch alternator would then require controlling 3rd, 5th, and 7th order harmonics by other means. In you experience is this done often?
Thanks for the Cummins power manual. It has a lot of very good information on paralleling generator sets and power systems in general.
09-19-2013 05:44 PM
Alternators go back to Mr Faraday and the 1860's, but I bet you would get an interesting conversation on that with both Mr Edison and Mr Tesla :-)
09-19-2013 08:32 PM
Will fractional pitch winding suppress all harmonics,what other measures to be taken?.
09-19-2013 11:02 PM
Use of fractional pitch windings allow the designer to minimize some harmonics, usually at the expense of higher harmonics in other harmonic orders. For example, 2/3 pitch machines result in 3rd order harmonics being almost completely eliminated.
The harmonics present in a generator waveform typical result in less than 5% total harmonic distortion, so there is no problem with respect to operating loads, but there can be issues when dissimilar generators with different harmonic content are paralleled.
09-20-2013 01:32 AM
Usually the percentage content of the higher order harmonics diminishes with the order of the harmonic. So if the lower ordeer harmonics of higher magnitudes can be contained, this minimises the general effects.