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).
Continued page detailing motor testing procedures, including light and load tests, and the relationship between voltage, current, and speed.
| Identifier | ExFiles\Box 70\4\ scan0146 | |
| Date | 30th January 1925 guessed | |
| -4- Contd. terminal voltage, which shall lie between the limits 9.5 and 10.0. Until the motor has been made to pass the light test, it should not be put on the load test because it would be found that a motor taking excessive current on the light test, due to bad magnetic circuit, would also take an excessive current on the load test for the same reason, and conversely a motor which has passed the light test will not, as a rule, take current in the load test in excess of 120 amperes. On the load test, provided the motor has a sufficiently good magnetic circuit to pass the light test, the specification that the ratio of the speed to the terminal voltage must exceed a certain figure, ensures that the electric circuit is good, that is to say, no undue amount of resistance is introduced in the shape of bad connections or brush contacts. Any such defects as these, by absorbing voltage, will lower the speed of the motor, because, other things being the same, the speed is proportional to the voltage that remains when the voltage required to drive the current through all the ohmic resistances of the circuit is subtracted from the available E.M.F., it being noted that the current remains the same for a given torque independently of volts and speed. Contd. | ||