Abstract :
The temperature limitations of electrical machinery, due to the properties and characteristics of insulating materials at present available, have served to focus attention on to the possibilities of asbestos. With the co-operation of Messrs. Turners Asbestos Cement, Ltd., of Rochdale, the E.R.A. has carried out a series of investigations extending over the whole field of asbestos products for electrical purposes, and is preparing a series of documents relating to the following classes:¿ (a) Asbestos yarns; (b) Asbestos fabrics and tapes; (c) Asbestos papers; (d) Asbestos-covered conductors. The present report deals exclusively with the study of asbestos yarns which, although admittedly of less general interest than the other three classes of material, are of prime importance as raw material in two of them. It is of interest to note that no tests are specified for electrical properties. This may at first sight appear to be anomalous, but the electrical properties of untreated asbestos yarn are known to be poor and to bear no relation whatever to those of treated or fabricated yarn where a filler or impregnating medium is employed. The Director of the E.R.A. will be pleased to receive comments from those who may have occasion to make use of this report.
