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).
Possibilities and implications of series winding on main poles for car dynamos.
| Identifier | WestWitteringFiles\V\2January1931-April1931\ Scan071 | |
| Date | 27th March 1931 | |
| ORIGINAL To R.{Sir Henry Royce} from EFC. C.S. [Struck through] C.D. Fy. [Struck through] C. Wox. TM [Struck through] HS.{Lord Ernest Hives - Chair} [Circled] EFC2/AD27.3.31. X.6099. R.R. CAR DYNAMOS. R1/M9.3.31. RECEIVED 1931 MAR 28 Serieswinding on main poles. The following possibilities present themselves :- (1) A series winding carrying the main dynamo current, this winding being introduced into the lead to one or other of the main (positive or negative) brushes. (2) A series winding carrying the constant (nearly) current of the head lamps. An equivalent variation of this would appear to be the provision of an additional (plain) shunt winding connected across the main brushes. (1) involves the least complication because no extra terminals, wires or switch contacts are required, the alteration being self-contained in the machine. It is not, however, by any means certain that such a winding would bring about the effect of maintaining the current level or nearly so at high speeds. So far as the matter can be thought out it would appear that any gain by this means would be too little to be worth while, it being always remembered that any such winding represents robs the ordinary winding of its winding space. (2) involves considerable complication i.e. not only the provision of the extra winding but also the provision of two extra dynamo terminals and two extra wires to carry the head lamp current through the dynamo. There will also be some loss of head lamp P.D. occurring in this winding and in our own opinion, although it seems certain that such a constant current would have a beneficial effect in boosting up the output at all speeds and also particularly at high speeds, it is not a practicable scheme. It is agreed that it would have the advantage of boosting up the dynamo output at the time only that it is required and also, on account of the extra load at this time, to a larger output than the dynamo can be allowed to give on the score of heating in the absence of that load. | ||