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<blockquote data-quote="Rack Failure" data-source="post: 78875" data-attributes="member: 5665"><p>Andy</p><p></p><p>The way I was taught many years ago, then rotor speed would be 960RPM or if you like 16RPS.</p><p></p><p>The formula then was:</p><p></p><p>Speed (RPM) = 60 x f/pairs of poles, which is equals to</p><p></p><p>Speed (RPM = 60 x 50/3</p><p></p><p>Speed (RPM) = 1000 (this 1000 is the synchronous speed of the rotating magneting field)</p><p></p><p>Slip is the speed the rotor lags behind (and must) the rotating field. 4% =40RPM. Hence 960RPM.</p><p></p><p>Just in case it is of interest, the value 60 is what converts the frequency from 50 cycles per second to cycles per minute, which in turn calculates speed in revs per minute.</p><p></p><p>It seems the modern way to calculate RPM is to use the value 120 x f / number of poles ie 120 x 50/6 = 1000 same answer.</p><p></p><p>The 120 is called a constant.</p><p></p><p>Hope this is of interest.</p><p></p><p>Steve</p></blockquote><p></p>
[QUOTE="Rack Failure, post: 78875, member: 5665"] Andy The way I was taught many years ago, then rotor speed would be 960RPM or if you like 16RPS. The formula then was: Speed (RPM) = 60 x f/pairs of poles, which is equals to Speed (RPM = 60 x 50/3 Speed (RPM) = 1000 (this 1000 is the synchronous speed of the rotating magneting field) Slip is the speed the rotor lags behind (and must) the rotating field. 4% =40RPM. Hence 960RPM. Just in case it is of interest, the value 60 is what converts the frequency from 50 cycles per second to cycles per minute, which in turn calculates speed in revs per minute. It seems the modern way to calculate RPM is to use the value 120 x f / number of poles ie 120 x 50/6 = 1000 same answer. The 120 is called a constant. Hope this is of interest. Steve [/QUOTE]
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