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).
Page 2 of electrical calculations for motor resistance, armature, and main field circuit.
| Identifier | ExFiles\Box 62\1\ scan0103 | |
| Date | 5th December 1932 guessed | |
| -2- Terminal volts = 8.00 Ohmic volts = 5.13 Motor resistance R = 5.13 = .0256 ohms. Assuming a main field resistance of .0060 ohms the armature resistance will be .0135 ohms, allowing .0061 ohms for brush and commutator resistance. Resistance of one armature turn. = (.0135 x 4) / 29 = .00186 ohms. Length of one armature turn = 9" Resistance per 1000 ft. = (12/9) x .00186 x 1000 = 2.48 ohms. Cross sectional area of conductor = LP{Mr Lappin}/R where L = length in cm. P = specific resistance R = resistance in micro ohms. = (1000 x 2.54 x 12 x 1.73) / (2.48 x 10^6) = .0214 sq.cm. or .0033 sq.in. Say for minimum heating .0040 sq.ins. Main Field Circuit. This should be as large a section of copper as can conveniently be accomodated with 3 1/2 turns per pole. | ||