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).
Improvement of dynamo commutation by modifying armature coil configuration.
| Identifier | ExFiles\Box 168a\3\ img138 | |
| Date | 24th January 1935 | |
| -6099. E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wat. c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wat.1/MA.24.1.35. Re. DYNAMO COMMUTATION. Some considerable time ago reference Hs{Lord Ernest Hives - Chair}/Wat.11/ MA.18.1.34., we wrote you suggesting that an improvement in the commutation of the dynamos could be effected with reduced overall losses by doubling the number of slots in the armature and spreading out the armature coils one coil per slot instead of two coils per slot as at present. We have recently had the commutation of our dynamo analysed on an oscillograph in the electrical laboratory of the Morgan Crucible Co.Ltd., who supply our brushes. They have sent some very interesting oscillograph records which show that we do not gain much with different grades of brushes in improving the sparking of our dynamo at high speeds, quoting from their letter they say "the most promising procedure appears to us to be to reduce the number of coils per slot. An advantage might be expected from two considerations. Firstly the field cut by the group of coils in a slot would be more uniform and, secondly, the mutual induction of the coils would be reduced." This rather confirms what we stated to you in our previous memo as referred to above, we therefore hope that you will agree to arrange for an experimental armature to be schemed out for us for the purpose of improved commutation at high speeds this being our greatest problem at the moment on dynamos. If we did not have to face this high speed commutation problem so severely we could considerably increase the cutting in speed of our dynamos by increasing the number of turns per coil. Hs{Lord Ernest Hives - Chair}/Wat. | ||