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 electrical design of connecting a cutout shunt and an auto switch.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 132 | |
| Date | 11th November 1927 guessed | |
| -3- Contd. (4) Cutout shunt connected to C and auto switch shunt connected to B. We have already pointed out that there is a reason why on present standard the cutout shunt coil positive should not be connected to B, i.e. without the auto switch, but there is very little objection to this connection if the auto switch coil is also connected to B, because the latter then protects the cutout shunt from the high voltage, except at very high speeds on open battery circuit (see below). Therefore, in applying the auto switch unit to existing cars, we should provide the six terminals and supply the auto switch shunt from B., as shown dotted in our diagram (attached to previous report), the dynamo field being of course supplied from C, via the auto switch contacts and resistance in parallel. In any new design, however, possibly it might, with some advantage, be arranged to connect both shunt coils together to C, i.e. in case the auto switch went out of action or was removed for any reason, when ordinary working, mainly as present standard could still be possible. (It occurs to us that although the auto switch might be designed as part of the complete distribution board unit, it could be removeable as a small unit, as also could the cutout in case of need). Therefore in the ones we arrange on cars, both shunt coils will be connected to B and that means no change in the existing arrangement, but only the addition of the auto switch unit, the three circuits of which are inserted in their respective positions electrically, i.e. two in existing wires and one between terminal B of the distribution board and chassis frame. | ||