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).
General report on the testing of various dynamos, focusing on volt-speed and ampere-speed curves.
| Identifier | ExFiles\Box 37\2\ scan 096 | |
| Date | 10th October 1920 | |
| R.R. 285a (100 T) (S.H 159. 11-8-20) G 3800 EFC5/T5.10.20. GENERAL REPORT. (1) Volt-speed Curves. These are open circuit volt-speed curves of the various dynamos tested, both for cold and hot conditions (carcase temperatures being given), for the useful range only, namely, from 10 to 18 volts, except for the Liberty dynamo where the actual voltages are two-thirds of the voltage given by the scale, owing to the fact that the Liberty is an eight volt machine. The two Smith dynamos which are normally controlled machines were temporarily converted into plain shunt machines by removing their control brushes, and setting the main brushes in the exact neutral position. The speed ranges between cold cutting in at 12.4 volts and hot cutting in at 13.6 volts are indicated. It will be noticed that the hot and cold operations of the Bosch machine are very nearly the same. This point, however, will be referred to later. It will also be seen that the operation of the Bosch is at the lowest speed of all the dynamos. It will be realised, however, that an early volt-speed curve may only be obtainable at the expense of a late ampere speed. (2) Ampere-speed Curves. It is therefore necessary to consider the ampere-speed performance in conjunction with the volt-speed performance. Curves of such performance are shown for both hot and cold conditions on the photostat sheets marked II, and these curves should be studied in comparison with the volt curves. Contd. | ||