. An elementary manual of radiotelegraphy and radiotelephony for students and operators . Fig. 3. all those on one side being of thean equal number of like poles onthe opposite side, of tlie opposite polarity. In this manner, thedisc was perforated by the magnetic flux passing across from oneset of poles to another, and the passage of the strips into whichthe disc is cut up, into and out of these streams of magnetic flux 84 RADIOTELEGRAPHY gives rise to the electromotive force in the armature. The arma-ture winding therefore consisted of a single disc-shaped conductorequivalent to a zigzag win
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . Fig. 3. all those on one side being of thean equal number of like poles onthe opposite side, of tlie opposite polarity. In this manner, thedisc was perforated by the magnetic flux passing across from oneset of poles to another, and the passage of the strips into whichthe disc is cut up, into and out of these streams of magnetic flux 84 RADIOTELEGRAPHY gives rise to the electromotive force in the armature. The arma-ture winding therefore consisted of a single disc-shaped conductorequivalent to a zigzag winding, and this was driven at a highspeed so that the radial elements of the armature cut acrossstreams of magnetic flux. A very strong excitation could there-fore be employed without producing any wasteful leakage chief defect of this design of armature is that unless the slitsin tlie disc are very close together, so that the width of the radialbar or slice is not more than -^ inch, there is considerable heatingof the armatuie, due to eddy currents set up in it. In one. Fia. 4. machine of this type, constructed by Tesla, the field had 480 polarprojections on each side, and from tliis machine it was possible toobtain a current having a frequency of 15,000 complete periodsper second. When a machine of this description having a discof considerable diameter is driven at a speed of 3000 , veryaccurate balancing is necessary, or otherwise dangerous vibrationswill be set up in the machine. Great rigidity and accuracy ofwork is therefore necessary in all parts of the machine, becausethe clearance between armature and field magnets must necessarilybe very small. There is very great difficulty in securing the necessary balanceIn any armature having wound coils upon it. ELECTRIC OSCILLATIONS 85 ITeDce tlio inductor form of alternator has been adopted iumost cases for lii;;h frociucm-y machines. The revolving part isthen merely an iron disc havinj, teeth or notches
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
