Nikola Tesla Books
THE HIGH POTENTIAL TRANSFORMER 25 The sections may be thick or thin, but however they may be, they should be wound in even layers with a layer of insulating paper between layers of wire. This rule is invariably followed throughout in the description of the windings. Enameled wire is favored in all secondary transformer windings. In the case of the induction coils, to be described, the wire may be cotton covered, as these windings are subjected to wax impregnation. The induction coil secondary is called upon to stand enormous potentials and it is subjected to but little heat. The transformer secondary. on the other hand, may become quite warm in operation and it should therefore be constructed to withstand this rise in temperature without deterioration. In this case, the enameled wire is excellent for it is impervious to moderate degrees of heat. Transformer Design.-The questions: "How many turns of wire do I use in the primary?" and "What size should the core be?" are familiar ones in the files of the author. The computation is simple and it does not involve any great knowledge of mathematics for its working-out. There are just a few basic principles to bear in mind before starting the calculation. The first determination is, of course, the capacity of the finished instrument. As the ½ k.w. size is a popular one, this size has been selected for the example. As the transformer is to be used for charging condensers, a large magnetic leakage is desired and this governs the shape of the core and the method of placing the windings. High efficiency is obtained only at correspondingly high cost and great weight of materials. In the present discussion of transformer design, the various computations have been reduced to the very simplest form possible in order that the scheme may be within the reach of any amateur worker who knows how to use simple
