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).
Issues with a new sequence starter motor (Scheme No.2), specifically the armature reaction effect from having too few turns in the main field winding.
| Identifier | ExFiles\Box 64\2\ scan0042 | |
| Date | 27th April 1927 | |
| To RHC.{R. H. Coverley - Production Engineer} from EFC. c. BY/RD. x7625 EFC5/T27.4.27. X.7625. SEQUENCE STARTER MOTOR ( SCHEME No.2) This motor has been instructed and assembled with three turns per pole to constitute the main field winding, the reason being the reduced reduction ratio as compared with the No.1 scheme. It now transpires from tests of two different natures, that the armature reaction effect of the armature on the main field is too great with this small number of turns, and that it will be necessary to revert to a larger number. In the case of the present motor, would you please have the field coils removed from the motor which has been taken off 14-EX and fit to this first motor of the No.2 scheme. This we understand is conveniently possible. Will BY/RD. kindly note that we are making investigations on this effect and we will let him know in due course as to what may be the correct number of turns per pole, taking the new reduction ratio into account. From phenomena observed on the new motor on preliminary bench test it will probably be necessary for us to write to Mr. Royce and give the opinion that we have robbed the main field winding space too much by the presence of the teazer winding, and that the general efficiency of the motor, at any rate for the new low reduction ratio, has suffered thereby. EFC. | ||