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 discussion on motor efficiency calculations, current, torque, and conductor design.
| Identifier | ExFiles\Box 64\1\ scan0128 | |
| Date | 30th May 1923 | |
| Contd. -3- EFC2/T30.5.23. 60%, resulting in a current of 145 amperes, in place of the 200 suggested by you, as this has seemed to be the only way of obtaining reasonable results in the calculations. We know from actual tests which we have made that the efficiency of this size of motor working at about 60 lb-inches of torque is in the neighbourhood of 60%. The assumption of increased efficiency puts up the number of armature conductors as a result of the reduction of motor current, but this is partly (only) counteracted by the larger flux density which appears necessary to suit these conditions. Speaking generally, since the torque required by this motor is low for its size, it follows that without an unreason-ably small flux per pole the number of conductors may be less than at first sight anticipated. MADE AT CROXLEY EFC. | ||