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 advantages of dispensing with the series coil and using rigid contacts in an electrical system.
| Identifier | ExFiles\Box 61\2\ scan0256 | |
| Date | 1st June 1927 guessed | |
| -5- Contd. It is an advantage to dispense with the series coil because:- (111) Of simpler design. (112) The elimination of the series coil carrying negative ampere turns due to a portion of the consuming load, removes from the system the last possibility of the existence of a high voltage therein on open or inferior battery circuit. It is an advantage to be able to use rigid contacts because:- (121) Of simpler design. (122) Of the material assistance given by the use of rigid contacts in preventing vibrator regulator action which would otherwise be liable to take place. This is brought about by the device as adopted in the R.R.unit of winding the resistance itself (which is in parallel across the switch contact) so as to provide additional ampere turns on the magnetic circuit of the auto switch. The use of rigid contacts enables the impulsive action of the sudden diversion of current through the resis- tence to be utilised whereas with spring supported contacts it would come at the wrong time, viz. too late to give the full impulse at the critical moment. It is an advantage to be able to use a much higher resistance and not have the trouble of vibrator regulator action or the phenomenon of low frequency vibration, bacause :- (131) At normal running speeds it enables the dynamo to be cut completely off charge when the voltage of the system has risen to the point of operation of the auto switch. This is an advantage because it avoids over- charging of the battery which might still occur if the charge is only reduced to half value. Contd. | ||