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).
External voltage and current regulators for chassis dynamos, and the definition of 'inherently controlled dynamos'.
| Identifier | ExFiles\Box 31\1\ Scan133 | |
| Date | 11th January 1922 | |
| To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EFC. c. to GJ. & FN. c. to Ey. & EP.{G. Eric Platford - Chief Quality Engineer} c. to Rg.{Mr Rowledge} & Ds. X/1402 EFCl/T3.11122 X.1402 - EXTERNAL VOLTAGE AND CURRENT REGULATORS FOR CHASSIS DYNAMOS. HS.{Lord Ernest Hives - Chair} tells me you have again under consideration the question of external chassis dynamo regulation, and it has occurred to me that you would therefore be interested in a summary of our impressions of this question. The term 'inherently controlled dynamos' as applied to those, the regulation of which depends upon armature reaction, is in a sense a misnomer. All dynamos of this type whether operating on a single field winding third brush system, the Trier & Martin four-brush system, the Lucas three-brush system, or the C.A.V. four-brush system, depend for their control by armature reaction on the fact of being connected to a battery. If any of these dynamos is run independently of a battery (but with its field, of course, connected up for excitation) this will produce a P.D. across its terminals which progressively increases with the speed, until in time the machine would burn out due to excess of field current. None of these machines, therefore, is proof against producing an overvoltage on the system, should the battery at any time be disconnected, either by accident or design, and the dynamo run. These dynamos therefore are not really 'inherently controlled'. The action should be expressed by saying that the dynamo is of such a type that when charging a battery its output is so controlled by armature reaction as to cause the charging | ||