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).
High tension D.C. tests of various insulating materials such as bakelite and redmanol.
| Identifier | ExFiles\Box 39\3\ Scan262 | |
| Date | 16th September 1926 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. PN.{Mr Northey} c. Da.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. EP.{G. Eric Platford - Chief Quality Engineer} Rg.{Mr Rowledge} c. Wor.{Arthur Wormald - General Works Manager} Rv. XJ513 EFC1/T16.9.26. HIGH TENSION D.C. TESTS OF INSULATING MATERIALS. XJ513 We have made a number of high voltage D.C. tests of bakelite insulating materials, comprising bakelised linen and canvas plates of various thicknesses, and redmanol coil cases. The tests have been carried out with the samples suitably arranged with tin foil electrodes in an electric oven in which any temperature from atmospheric up to 100°C can readily be obtained. In order to obtain a high tension D.C. voltage for the testing of these materials, we utilised our high tension A.C. transformer in conjunction with a small rectifying valve - sometimes called a Kenotron - though actually an ordinary radio receiving valve equally suitable for the purpose was utilised. A diagram of the arrangement is given, from which it will be seen that the battery lighting the filament is at the high D.C. test potential. The actual leakage currents through the materials on test were measured by a D.C. instrument used as a milliammeter, which instrument also was at the same high tension potential. In the majority of tests the H.T. transformer tapping was such that an open circuit R.M.S. A.C. voltage of 2400 was provided, though in some of the tests on the thinner materials this was reduced to 1200 by halving the supply voltage to the primary of the transformer. The respective maximum values corresponding to these figures would be 3400 volts and 1700 volts. Contd. | ||