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).
Description of the operation of the automatic dynamo charging system and relay unit.
| Identifier | ExFiles\Box 61\2\ scan0236 | |
| Date | 2nd June 1926 | |
| Contd. -11- EFC1/T1 2.6.26. reversely effective as compared with that of the volt coil. There is of course the usual automatic cut-in and cut-out in addition to this relay unit. Supposing for the moment that the system is unloaded, except for starter motor load at starting, every time the chassis engine is started up we find the electro-magnetic switch closed, so that the dynamo proceeds to cut in and charge at the full normal rate. Such charging will continue until by rise of back E.M.F. of the battery the voltage of the system has risen to a pre-detemined amount, say about 17 volts. The automatic switch then opend and the field resistance is inserted. The output of the dynamo falls to this reduced output curve for varying speeds and the switch remains in the open position so long as running is continued, whatever the duration of the run, the battery therefore receiving a relatively short initial 'boost' and afterwards a reduced rate of charge continuously. On stopping or slowing down sufficiently for the cutout to come out, the relay switch is restored to the "on" position, and then upon again starting or reaccelerating, the same process is repeated. If, now, during any run a load is switched on to the system, this, if a comparatively light load, owing to its reverse effect on the electro-magnetic switch, necessitates a voltage rise to a slightly higher value before the Contd. | ||