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).
Tests on bakelised plates and coil cases, investigating issues with insulation resistance and leakage currents.
| Identifier | ExFiles\Box 39\3\ Scan265 | |
| Date | 16th September 1926 | |
| Contd. -3- EFCL/T16.9.26. The reason why the tests on the bakelised plates were undertaken in the first instance was that it was found that the insulation resistance of dynamos did not satisfy the limiting figure given when a certain kind of bakelised linen plate material was used for the insulation of the brush holders. As will be seen from the results, there are wide divergencies in the leakage currents of these materials. The reasons for the differences appear tobe - (1) Colouring matter. (2) Degree of curing of the bakelite filler. 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 Contd. | ||