This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ...If we make the pole face narrower say one half the pole pitch the mean ordinate of the shaded area becomes a little larger. In this case the shaded area is j.g and the mean ordinate is 2.32qi. By narrowing the pole face we have slightly increased the coefficient. If we were to reduce the polar face to one.third of the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: ...If we make the pole face narrower say one half the pole pitch the mean ordinate of the shaded area becomes a little larger. In this case the shaded area is j.g and the mean ordinate is 2.32qi. By narrowing the pole face we have slightly increased the coefficient. If we were to reduce the polar face to one.third of the pole pitch the coefficient would be 2.45. To cover all cases we may write generally X = aqi (64) The bevelling of the polar edges has the effect of concentrating more of the flux in the middle and this has the same result as narrowing the poles. Thus with bevelled edges and a polar angle of 120 the coefficient will be a little greater than 2.12. The value assumed in practice is 2.2, so that the formula for armature ampereturns with coils sides of one.third and pole faces of two.thirds of the pole Pitchis X = 2.2qi (65) Similar calculations may be made for the case of wide coil sides. The graph of exciting force is shown in the lower part of Fig. 93. The outlines have the same shape, but the maxima are in both figures reduced in the ratio of 2 to /3. It is therefore not necessary to go through the calculation in detail; all we need do is to reduce the value of a in this ratio. This gives a = 1.9. With a lag of 90 X is a back excitation reducing the flux and therefore lowering the voltage of the generator. The back excitation is proportional to the slice cut out from the equivalent sine curve of the graph of total armature ampere turns. By a well.known theorem of trigonometry the area of such a slice is itself a sine function of the position where it is taken. In the case illustrated in Fig. 93 the internal phase angle ip is 90 and the area of the slice is a maximum; if the internal phase angle were zero the area (being one half positive and the...
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Add this copy of The Principles of Electrical Engineering and Their to cart. $33.28, new condition, Sold by Ria Christie Books rated 4.0 out of 5 stars, ships from Uxbridge, MIDDLESEX, UNITED KINGDOM, published 2022 by Legare Street Press.
Add this copy of The Principles of Electrical Engineering and Their to cart. $38.38, new condition, Sold by Books2anywhere rated 5.0 out of 5 stars, ships from Fairford, GLOUCESTERSHIRE, UNITED KINGDOM, published 2022 by LEGARE STREET PR.
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Add this copy of The Principles of Electrical Engineering and Their to cart. $40.20, new condition, Sold by Paperbackshop International rated 1.0 out of 5 stars, ships from Fairford, GLOS, UNITED KINGDOM, published 2022 by LEGARE STREET PR.
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Add this copy of The Principles of Electrical Engineering and Their to cart. $40.73, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2022 by Legare Street Press.
