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).
Technical memo discussing dynamo performance, output curves, and comparison with other models.
| Identifier | ExFiles\Box 36\4\ scan 066 | |
| Date | 29th May 1920 | |
| Contd -4- EFC1/T29.5.20. normal speed vary a little. On any one dynamo the output curve of the machine can be considerably increased or reduced, respectively, by advancing or retarding the control brush. We are not quite sure yet, but are further investigating the matter, as to what should really determine this setting, as it is a fact by increasing the output of the machine by this means, we reduce the control current at the higher speeds. We hope, however, to give you more information on this point shortly. The curves given are, of course, given for the maker's setting of the control brush. Comparison of the curves will show that in using the C.575 machine we should gain a small area of output in the earlier stages at the expense of a much larger area of output in the later stages, both for the hot and cold conditions. In our own mind it is very doubtful, owing to the difference in magnitude of these areas, if this is really desirable. As already stated, what we have urged for all along is a cutting in speed approximately as now obtained on the C.575 together with the hot output of round about 10 amperes instead of 8 as for this machine, and we think that this would meet the case satisfactorily. It would be still better, we think if the dynamo could be so arranged that the output should run up to 12 amperes at about 1100 R.P.M. and then droop away to possibly 8 amperes at very high speeds. This latter is the sort of performance that we are obtaining from the Smith dynamos which are, however, about 2 lbs heavier. Contd | ||