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).
The efficiency principles and testing conditions for a series starter motor.
| Identifier | ExFiles\Box 61b\3\ scan0101 | |
| Date | 15th July 1929 | |
| 15.7.29. X 548 86027 SERIES STARTER MOTOR. EFFICIENCY PRINCIPLES. For consideration of efficiency we think of the current as the independent variable and take various values in turn. For each value the brake test terminal voltage is fixed by the law of supply adhered to, and this current and voltage will determine uniquely the torque and speed on that test (temperature of motor supposed given). For each given value of the current we think of the motor in three different conditions :- (1) The motor running normally on the brake test with the given current and corresponding voltage E.{Mr Elliott - Chief Engineer} There will be a torque on the brake wheel whose value may be measured and whose value at armature speed (instead of at brake wheel speed, if there be a reduction ratio) be called Tr.{Capt. F. W. Turner - Finance} The armature speed will also be measured. (2) The given current passing round the field winding and the armature driven at the speed at which it runs on the brake test. There will be a flux per pole Øe usually rather greater than that on the brake test, and an E.M.F. ee generated in the armature which E.M.F. may be measured, and Øe estimated from it and the speed. (3) The given current passing through the whole motor, but the motor being prevented from turning. There will be a flux per pole Øs and a torque Ts on the armature conductors, which torque may be measured, and Øs estimated from it and the current. contd. | ||