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).
Calculation sheet for electrical motor resistance and conductor dimensions.
| Identifier | ExFiles\Box 179b\2\ img129 | |
| Date | 12th November 1932 guessed | |
| -2- Terminal volts = 8.10 Ohmic volts = 6.32 Motor resistance R = 6.32 / 195 = .0324 ohms. Assuming a main field resistance of .0060 ohms the armature resistance will be .0203 ohms, allowing .0061 ohms for brush and commutator resistance. Resistance of one armature turn = .0203 X 4 / 25 X 1 = .0032 ohms Length of one armature turn = 9" Resistance per 1000 ft. = (12 / 9) x .0032 X 1000 = 4.27 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 / (4.27 X 10^9) = .0124 sq.cm. or .00192 sq.in. Say for minimum heating .0036 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. | ||