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).
Extract detailing tests of insulating materials for coil cases.
| Identifier | ExFiles\Box 69\1\ scan0035 | |
| Date | 16th September 1926 | |
| X.40796. X8710 To R.{Sir Henry Royce} Extract from EFCl/T16.9.26. (For original see X.3513.) H.T.D.C. TESTS OF INSULATING MATERIALS. In the case of the coil cases, the idea was to develop a test which could be applied to redmanol coil cases on production, which would indicate directly whether each coil case were sufficiently good in this respect to be passed for production; and also that the information given would be generally valuable in view of our experience with moulded bakelite material for coil cases. The development of the production test for coil cases has not yet been completed. In this case we hope to use a high tension trembler ignition coil for the supply of the necessary current to be rectified by the valve. The voltage will not be known precisely but the tests will be comparative. Apparently our early trouble with moulded bakelite cases would appear to have been largely due to this leakage conductance combined with a dielectric hysteresis effect which perhaps would naturally be associated with it. It would appear that the improvement has been largely due to experience on the part of the Production Dept. in the proper curing of these cases, because it is quite clear from comparative results even now that there are variations from coil case to coil case, and variations according to the subsequent heat treatment of any individual coil case, also though it may not be realised, the leakage of these redmanol coil cases is even now many times | ||