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).
Proposal document detailing calculations for the number of slots and chording for a 20 HP armature.
| Identifier | ExFiles\Box 68\4\ scan0253 | |
| Date | 28th March 1928 guessed | |
| -3- Contd. This is less than before whereas we want more. Therefore we suggest 26 or 24 slots each .166 x .487" Oce at neck = 7.07" in each case. 1/26 of this = .272 Slot = .166 Neck = .106 1/24 of this = .295 Slot = .166 Neck = .129 24 slots give a number viz. 288. of conductors _2_ less than 3 of the standard number. This is considered too small. Hence we adopt 26 slots. With this number we may have a coil step of 6 (1 to 7) with no short chording or alternatively a coil step of 5 (1 to 6) with two degrees of short chording. Even this amount of short chording does not on a winding diagram appear excessive. It is therefore proposed to make a 20 H.P. armature thus short chorded. Contd. | ||