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 motor E.M.F. and resistance, including armature and field resistance.
| Identifier | ExFiles\Box 64\1\ scan0131 | |
| Date | 30th May 1923 guessed | |
| -3- Contd. The back E.M.F. when rolling engine Ø Z N P = --------- 60 x 10^8 x b 201,000 x 74 x 1200 x 4 = ----------------------- 60 x 10^8 x 2 = 5.95 volts Forward E.M.F. at motor terminals = 9.00 Hence E.M.F. for resistance = 3.05 volts. Total motor ohms are therefore 3.05 ---- = .021 = R (say) 145 Let field resistance = R_F and armature " = R_A and allow R_F = 11/7 R_A and .003 w for brush contact resistance Then R_A = .007 w R_F = .011 R_B = .003 ---- Total R = .021 w. Resistance of one armature turn .007 x 4 = -------- 37 = .000757 w Length of armature turn = 11" approx. | ||