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).
Issues with dynamo output, including falling current at high speeds and due to heat, and potential solutions.
| Identifier | ExFiles\Box 163\6\ img119 | |
| Date | 6th January 1931 | |
| X6016 Sg.{Arthur F. Sidgreaves - MD} Hs.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} EFC. } (At Le CanadelHenry Royce's French residence) R3/M6.1.31. c. Wor.{Arthur Wormald - General Works Manager} Da.{Bernard Day - Chassis Design} PN.{Mr Northey} X.6084. DYNAMO OUTPUT X.6004. X.6016. X.6006. The complaints such as output of dynamo we can put right, but I think we are not going the right way to touch the real trouble. Most of the complaints seem to indicate that owing to the greater consumption of current the dynamo output is not large enough. Therefore we must get more current especially at higher engine speeds - (Characteristics should not fall, and also there should be less falling off with heating of the dynamo). We cannot afford at the moment to do anything with the two rate scheme. We had better charge our battery when we can, and as fast as we can. I am anxious not to increase the size of the dynamo, and I feel sure that an increase in the size of the battery would not do any good unless it were increased in such a way as to better bear a larger charging current, but my advice for the moment is not to spare the battery. We must, however, avoid roasting the dynamo. Apparently we have not done so, therefore having reduced the falling off with speed as before instructed, let us examine the falling off with heat. With the 3rd. brush scheme there is a tendency that when the opposing EMF. rises the current increases, and when it falls the output falls, and also one imagines that an increase of temperature (rise of resistance of the exciting circuit) reduces the output more than one would expect. This is good to save the dynamo from roasting itself but everything seems to be bringing down the available current under the conditions stated when Hs.{Lord Ernest Hives - Chair} said the available current was insufficient to maintain the lamps. This never should be so, and one thinks is very easily tested. Now we have EFC. and his assistants, Mr.Brock, and Mr. Hives dept., each on the lookout to keep their part of this work right, but we seem not to know quite where we are. For instance I do not remember hearing that our system was so bad as it appears to be, and we seem to be doing the wrong thing in trying to save the battery. | ||