From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Page discussing the properties and testing of insulating materials, referencing German standards.
| Identifier | ExFiles\Box 24\2\ Scan092 | |
| Date | 25th January 1921 guessed | |
| - 5 - The percentage of energy losses in insulating materials grows considerably with increase of temperature. Good insulating materials should not only be able to withstand electric influences, but should be mechanically strong impervious to dampness and oil, easily machined, able to withstand heat, and if possible, fire, and have a long life, that is to say, they should not age and should be able to resist the chemical action and effects of weather. There is no material that combines all these properties, and it is for the designer to choose, according to his purpose, the dielectric which satisfied the particular conditions in the most perfect manner. Furthermore, commercial questions are of importance as prices for different insulating materials differ very greatly. A specially appointed Committee of the Institution of German Electrical Engineers is occupied in compiling a record of the properties of dielectric materials that are available for use in heavy current installations, and in determining what qualities are to be demanded in special insulating materials with due reference to advances in their methods of manufacture and in issuing Regulations for their use. Insulating materials for high voltages and other purposes have not yet been treated, but will be at a later date. The present classification refers to insulating materials used on voltages of about 500 to 100 volts. The result of many years work of this Committee is contained in the so-called "Short Regulations for Testing" which have been drawn up in collaboration withthe "Physikalischtechnis-che Reichsanstalt, the Kgl. Materialprufungsamt, the Kgl. bayriesche Lan desanstalt" and representatives of manufacturers. I myself took part in the discussion in my capacity as manufacturer. The experiments on insulating materials cover their bending strength and resistance to blows, hardness to impression by spheres, resistance to heat and frost, resistance to flame and besides the measurement of the surface insulation referred to, their resistance to arcing. Formerly mechanical and chemical properties were neglected in estimating the value of insulating material, and the tests were almost confined to electrical ones. This method of regarding them is wrong in principle, and involves a purely one-sided examination. Theoretical and practical experiments show that mechanical and chemical strength must receive equal consideration with electrical strength. There are, for instance, insulating materials, that withstand high voltages but become soft at low temperatures, for example - 80 to 100 degrees.centigrade. [Handwritten in right margin] considerations | ||