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).
Explanation of the dynamo's charging circuit operation and fuse provisions.
| Identifier | ExFiles\Box 61\2\ scan0139 | |
| Date | 6th October 1919 | |
| Contd. -5- EFC2/T6.10.19. The operation of putting on the charging switch virtually makes three of the connections from the dynamo, for instance, field control, and negative, into one common connection. It is necessary to have these points separate from one another, as if not, the dynamo when not required to charge, would be excited unnecessarily while not doing any useful work. There is provision for a light fuse on the Lucas board, between the field terminal and the corresponding point on the switch. If at any time the dynamo should be switched on without a battery connected on the chassis, and run at a fair speed with the charging switch on, this fuse would be melted and prevent the dynamo from being over-heated and possibly burnt out. The fact that the control circuit would still be complete would not matter, as this could not cause any damage. Spare fuse wires for this are provided in a little container in the switchbox. In addition to the series coil of the cut-out through which the main charging current passes when automatic contact is made, there is a shunt coil connected between the main positive and negative terminals of the dynamo and it is this shunt coil which, when the dynamo is allowed to excite by being driven with the charging switch on, causes the automatic contact to be made. Subsequently if the speed of the dynamo is increased, the main charging current in passing through the series coil, assists in holding the contacts together. Contd. | ||