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).
Results of tests on dynamo commutation, comparing different armature coil configurations.
| Identifier | ExFiles\Box 62\3\ scan0434 | |
| Date | 29th June 1934 | |
| 86066 E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By/RD. Hs{Lord Ernest Hives - Chair}/Wst.5/MA.29.6.34. DYNAMO COMMUTATION. Referring to your E.8/HP.28.6.34., we completed this test some time ago and discovered no improvement in the fitting of a dummy coil. Generally the sparking that takes place in any case, particularly at high speeds due to armature reaction, jumping of the brushes etc., is so great compared with that due to the lap coil that the latter can be ignored. At the end of a test run over a long period with the 47 coil armature the commutator and brush wear appeared to be just as bad as with a 48 coil armature. On the other hand the 47 coil armature has disadvantages in that there is a displacement of the conductors with respect to the field which may cause extra sparking independently. There is also the loss of the conductors of one coil. We suggest therefore that any further tests in this direction be left over until general sparking from other causes has been reduced to a minimum. Hs{Lord Ernest Hives - Chair}/Wst. | ||