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, safety from over-heating, and design compromises.
| Identifier | ExFiles\Box 165\6\ img235 | |
| Date | 4th December 1929 | |
| EFC2/ADL4.12.29 contd. -2- which means of practical necessity cases where there is no control, the great limitation of output as mainly determined by control brush setting, is that of armature heating with the dynamo running approximately continuously at such a speed as to be charging at its maximum or peak rate. The point that it is wished here to emphasise, is that the possible output of the dynamo for far the greater percentage of the time it is run, is less by say 20% than it might be if there were output control, on account of the necessity of safety from over-heating in all circumstances. . In the early R.P. dynamos, the margin of heating safety was slightly too small and molten commutator solder and charred armature were the occasional result. As dynamos have been developed so as to give, amongst other improvements, more output for the same degree of heating, the margin of safety has been increased to an amount universally satisfactory in the present circumstances of manual or no control, without loss of output but nett gain. With output charactertistics subject to the limitations above noted it is, in our up-to-date opinion, the case that outputs only slightly higher on the peak than the present standard outputs, and falling away at high speeds by a similar amount, still represents the best compromise between the extreme cases for which we have to cater. We are of the opinion that the extreme case represented by the following quotation from,one of | ||