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).
The specifications for the winding of a C.A.V. N.G.R.R. type dynamo.
| Identifier | ExFiles\Box 39\2\ Scan016 | |
| Date | 17th September 1919 | |
| To Da.{Bernard Day - Chassis Design} for Mr. Thacker. X.3533 FFC5/T17.9.19. from EFC. X.3232 - C.A.V. ARMATURE. X.3533 - 20 H.P. DYNAMO. The particulars of the C.A.V. N.G.R.R.type dynamo winding are as follows:- Number of poles 2 Number of slots. 24 Type of winding. Progressive lap. Number of conductors 672 Number of conductors per slot 28 Number of coils per slot 2 (The two coils per slot as you will see from sample coil herewith, though in reality two coils, are bound up together as one c il, the middle connection of which is connected to the commutator segment lying between the segments corresponding to the two ends of the compound coil). Number of coils 48 (i.e. 24 compound coils) Turns per coil 7 i.e. 14 per compound coil. (Considering the 7 turns per coil as one turn for the purposes of a winding diagram, there would be 96 virtual conductors, the winding pitch would then be 49 conductors forward and 47 backward). The winding pitch in the slots is 12, i.e. a step of one to 13. Diameter and active length of armature = 3 1/4" diameter by 2 3/4" long respectively. You will be able, from the total number of conductors and the open circuit voltage, to calculate the flux produced corresponding to any number of ampere turns by excitation, with the aid of the curve already given to you, which we hope will be of assistance to you in deciding what amount of flux we can | ||