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).
Dynamo output limitations and a recommendation for an experimental air-cooled dynamo.
| Identifier | ExFiles\Box 62\3\ scan0442 | |
| Date | 24th July 1934 | |
| -2- Hs{Lord Ernest Hives - Chair}/Wst.5/WA.{Mr Wallis}24.7.34. Cont'd.{John DeLooze - Company Secretary} The high speed output of 13.5 amperes, represents the limit to which this method of raising the output can be used, with the present machine, as at this point commutation became increasingly unsteady, and the output fluctuating. (2) A considerable increase in output can be obtained, for a given temperature rise, with quite a small rate of flow of air (at atmospheric temperature) passing over the commutation and brush gear. This increase in output can be obtained at both low and high speeds. The limit, to which the output can be thus raised, occurs at the maximum speed, and is set by the sparking at the brushes, and the resultant unsteadiness of output, (as shewn by the ammeter) and rapid wear of the brushes. Since an increase in output at high speeds, is more desirable, and this is limited by commutation, it appears that work, such as that involving specially shaped pole-shoes, series winding etc., for the improvement of commutation, should be carried out first. On the other hand, there wouldbe some gain in fitting a small fan to the present machine; but the amount gained would probably not be worth the expense. The immediate benfit of air cooling as far as we are concerned would be the use of a much smaller dynamo thus reducing weight. We recommend therefore that an experimental R.R. Sch.481 dynamo be put in hand as soon as possible with a small "Sirroco" type fan incorporated at the commutator end. Hs{Lord Ernest Hives - Chair}/Wst. | ||