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).
Auto switch and dynamo characteristics, proposing an investigation into achieving a flatter generator output curve at high speeds.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan006 | |
| Date | 5th December 1927 guessed | |
| -2- Contd. the auto switch is very much less likely to operate at high speeds than at moderate speeds, and when it operates at such a speed that the dynamo output is a maximum, in that case the cutout immediately comes out (this is speaking of 20 HP. conditions - 40/50 HP. conditions have not yet been thoroughly explored). As previously pointed out it only takes the load of the side and tail lamps to effect a considerable delay in the operation of the auto switch. Speaking of the shape of the dynamo output characteristic we yesterday received the suggestion that with the auto switch we should use a generator which had a flat-top characteristic from moderate to high speeds, in order to obtain full output at high speeds at night. There is a good deal to be said for this and the probability is that the right thing to do would be to effect a compromise - that is to say, not have a perfectly flat-topped curve (one of the reasons against this being as above described) but one that did not fall so much as our present machine. This we think would be right. It is not readily possible to obtain such a curve with the ordinary third brush method of control without a loss of cutting-in speed. We propose to investigate what can be done in this direction in the way of producing a curve which, though falling to some extent at high speeds, does not fall as much as our present representative generator curves. EFC. | ||