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 performance, specifically changes to field windings and armatures to manage temperature and output.
| Identifier | ExFiles\Box 62\3\ scan0237 | |
| Date | 1st July 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Pgt. c. Sg.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} c. FN. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} RV. X6008 Hs{Lord Ernest Hives - Chair}/Pgt3/ADS.7.31. X6008, X6126 X6099 DYNAMO PERFORMANCE. With reference to your H3/M24.6.31. As regards increasing the span of the field winding, the main difficulty is, of course, to do it without increasing the temperature rise of the machine.+ We have found, however, that we can do this to a certain extent by using a field winding/with a larger number of turns of finer wire. wound The effect of this finer winding is shown by the accompanying curves. It will be seen that, for the same temperature rise, the cutting in point is somewhat later with the finer winding, but in return, the peak is considerably higher and the output maintained better at high speeds. In addition there is the advantage that the field current is smaller, so that commutation at the control brushes should be better. In connection with the suggestion of having three armatures made with progressively larger slots, our experience in this direction is that the cutting in point becomes later as the slot is enlarged, although the curve does become more level. It may, therefore, be advisable to use the extra space available in the wide slots to accommodate a judicious combination of extra turns and heavier gauge of wire, rather than fill it up by increasing the gauge of wire alone. We are, however, having three armatures made with which to fully investigate the idea, keeping the number of turns constant as suggested, but increasing the gauge of wire as far as possible. + If we add resistance to keep temperature down we get late cutting in. Hs{Lord Ernest Hives - Chair}/C. A.{Mr Adams} Pignatt. Print attached. | ||