The manufacture of electrical condensers

G.F. Mansbridge
1908 Journal of the Institution of Electrical Engineers  
Although electrical condensers are among the oldest devices in the art of applied electricity, it is only within the last few years that the demand for them has assumed any degree of commercial importance. Until about 1898 practically the whole of the supplies were for telegraph work, but since then the situation has been entirely changed by the great development of the telephone service of the world, and particularly of the common-battery system, in which condensers play a modest but important
more » ... odest but important role. The magnitude of the present demand may be gauged from the fact that the aggregate output of condensers in Europe and America during 1907 is estimated at the once-inconceivable capacity of 5 farads. With manufacture established on this scale, economy in production is imperative, and the skilled hand of the 'nineties, who laboriously assembled or "built" his 1 or 2 microfarads per day, has given place to the machine hand who, with less physical distress, readily turns out one hundred times that quantity per diem. As a result the manufacturing costs have been so greatly reduced that condensers equal in quality to those produced ten years ago can now be purchased at approximately one-tenth the price. This reduction in cost has brought about a yet further increase in the demand, since it now. pays to employ condensers for many services from which they were previously shut out by their high cost. Consequent, no doubt, upon the newness of the industry, very little seems to have been published in the way of precise physical, electrical, or manufacturing data, and the present paper is an attempt to deal with some of the technical points which seem to be of the most importance in the manufacture and use of condensers. Throughout the paper the subject has been looked at chiefly from the point of view of the practician ; the numerical data quoted must therefore be considered, not as figures obtained in a laboratory, but as representing the carefully digested results of workshop tests made in the ordinary course on large batches of condensers. These tests, though made with reasonable care, may not be of the high order of accuracy obtainable with tests of isolated specimens taken under laboratory conditions, but it is thought that their accuracy is sufficiently
doi:10.1049/jiee-1.1908.0063 fatcat:7n2hfg3a4jbfro3wteq5prguaa