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Title: |
1909 Article-Stow Mfg. Co., 4 Pole Multi-Speed Motor |
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Source: |
Cyclopedia of Applied Electricity, 1909 pgs 446-447 |
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Insert Date: |
11/14/2011 1:04:47 PM |
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Stow Manufacturing Company — The Stow multi-speed motor, as it is called, really belongs to the adjustable-speed class, obtaining its speed variations by changing the reluctances of the magnetic circuits. It is bipolar in sizes from ¼ to 4 H. P. and 4 pole from 4 to 15 H. P. Fig. 100 shows one of the 4-pole types. The pole cores -are made hollow and provided with iron or steel plungers, the position of which is adjustable through pinions and worm gears operated by a large hand wheel placed on the top or the side of the machine as preferred. When the plungers are withdrawn, the total flux decreases because of the lengthening, and the decrease in the effective area, of the air gap and also the decrease of effective metal in the field cores. The speed must necessarily increase with decrease of flux. Also, when the plungers are withdrawn, the flux is along the polar edges, thus maintaining a strong commutation field and also decreasing armature reaction by increasing the reluctance of the armature flux. These effects allow sparkless commutation at any load at any speed within the limits of the design. These motors can be designed to give a speed variation of 3 to 1. |
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1909 Stow Mfg. Co., 4 Pole Multi-Speed Motor
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