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 and specifications for motor speed, resistance, and windings.
| Identifier | ExFiles\Box 62\1\ scan0101 | |
| Date | 12th December 1932 guessed | |
| -2- Motor speed 880 R.P.M. Back E.M.F. when rolling engine = (Φ Z N P) / (60 x 10^8 x b) = (194 x 10^3 x 58 x 880 x 4) / (60 x 10^8 x 2) = 3.30 volts Therefore ohmic E.M.F. = 7.60 - 3.30 = 4.30 volts Motor resistance R = 4.30 / 220 = .01955 ohms. Let field resistance be .0060 ohms. and brush contact drop .0060 ohms Then armature resistance = .0075 ohms. Resistance of one armature turn = (.0075 x 4) / 29 = .00103 ohms. Length of one armature turn = 12" approx. . . . Resistance per 1000' = 1.03 ohms. Ohms of copper per 1000' at 20°C. = .00815 ÷ cross sectional area = .00792 sq.ins. Wind with armature strip to E.13741. For 33 slot armature wind with armature strip to D.53139. Main field winding to consist of 3 1/4 turns per pole of field bar to drawing D.71936. Teazer field winding - 27 turns of 18 S.W.G. D.C.C. Main poles to be increased in section by .100" over the width as shown on D.53165. Main and teazer to be in parallel. Hs{Lord Ernest Hives - Chair}/Wst. | ||