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).
The performance and specification of dynamo cutouts and their interaction with the battery.
| Identifier | ExFiles\Box 48\3\ Scan253 | |
| Date | 12th May 1921 guessed | |
| EFC {E. Fowler Clarke - Electrical Engineer} 2/T. -3- Contd. 5. It would be very unlikely that the "hunting" effect mentioned would be produced. This might occur if the battery had been receiving the charge from an outside source, and be immediately placed on the car and be charged by the dynamo with the cutout cold, but in the ordinary way the voltage of operation of the cutout as it warms up will rise so immediately that even if the battery had been fully charged at the last time of running, it is very doubtful whether, with the figures we have given, the battery E.M.F. would be greater than the dynamo E.M.F. at the point of cutting in. 6. Peculiarly enough, the first cutout sent to us operated almost exactly to our specification. It was made to operate entirely to our specification by including a little more resistance in the compensating circuit, and it then operated perfectly and definitely with only a very small reverse current. The second cutout was also very good in this respect and in the main complied with our specification. These two cutouts were apparently made and assembled in France. The other cutouts we have received have been, in our opinion, badly adjusted. 7. Referring to the paragraph in their letter relating to dynamos having a definite amount of armature reaction, we do not see any reason why this should affect the operation of the cutout. The cutout operates when the E.M.F. attains a certain value on its terminals irrespective of whether this be produced by one kind of dynamo or another. Yours faithfully, | ||