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).
Technical discussion on dynamo switchbox equipment for the Goshawk, comparing two vs. three conductor switching.
| Identifier | WestWitteringFiles\G\September1921\ Scan93 | |
| Date | 30th September 1921 | |
| R.R. 285A (100 T) (S.H. 798. 10-12-20) G 2947 Contd. -2- EFC1/T30.9.21. switchbox equipment you have under consideration for the Goshawk you are only providing means of switching two dynamo conductors to the line wire, whereas the standard Lucas requires means of switching three dynamo conductors to the line wire. It was reported early on (EFC1/T10.5.19) that in the case of the E.575 type of dynamo, the control terminal might be left connected to the negative terminal, probably without any harm, when the switch was taken off, thus necessitating the use of a three-point switch only. The circulating current which would always be running whilst the dynamo was rotating would not be more than in normal operation, and the sparking also not more than in normal operation. In the case of the present dynamo, however, in order to get an output curve more nearly in accordance with our requirements, i.e. one which falls appreciably in the later stages, they have caused the control winding to have a greater effect proportionally than the field winding, reducing the main field excitation (excited across the main brushes) to a relatively much smaller amount. The control effect has been made greater perhaps partly by using the control brush in a very advanced position and partly by using a relatively heavier control winding. We propose, on this machine, experimenting with the control terminal left connected to the negative brush, both on the bench and actually on the Goshawk car, as it may not be possible with the switching arrangement | ||