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).
Calculations for back E.M.F. and total motor resistance.
| Identifier | ExFiles\Box 64\1\ scan0147 | |
| Date | 19th June 1923 guessed | |
| -3- Contd. The back E.M.F. when rolling engine = Ø Z N P --------- 60 x 10⁸ x b = 200,000 x 82 x 900 x 4 ---------------------- 60 x 10⁸ x 2 = 4.92 volts Forward E.M.F. at motor terminals = 8.44 Hence E.M.F. for resistance = 3.52 volts Total motor ohms are therefore 3.52 ---- = .020 nearly. 178 = R (say) Let field resistance = Rꜰ and armature " = Rᴀ and allow Rꜰ = 10/7 Rᴀ and .003 w for brush contact resistance. Then Rᴀ = .007 w Rꜰ = .010 w Rʙ = .003 w ------- Total R = .020 w Contd. | ||