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 report on dynamo heating tests, comparing temperature measurement methods and analyzing cut-in speeds.
| Identifier | ExFiles\Box 3\5\ 05-page161 | |
| Date | 1st March 1920 | |
| -2- CK{Mr Clark}2/T4.3.20. To R.{Sir Henry Royce} contd. the bulbof which is immersed in a little copper oil bath on a copper saddle fitting over the dynamo carcase, and these do not represent anything like the inside temperature of the armature and field windings. (In passing we may remark that we have already taken a number of heating tests on several dynamos in which we have observed temperature, both by this means and by calculating the temperature from the increase of resistance of the field coil. Curves showing the rise of these two temperatures and the corresponding fall of ampere out-put with time will be sent to you in due course). Thinking of the E.M.F's 12.4 and 13.6 as being the standard for cold and hot,(it being considered that 12.4 represents the E.M.F. of a battery fully charged, but which has been standing for some time, and 13.6 represents the same when the battery has just been gasing up on charge, and assuming that these E.M.P. figures are taken in conjunction with the cold and hot condition of the dynamo respectively), it will be seen that with the Lucas dynamo cold, the true cutting in speed (balancing speed) or speed at which the ideal cut-out would operate) is round about 600 R.P.M. and that with the machine in a hot condition, this becomes about 720 for the 13.6 volts mentioned, these figures being the averages of several dynamos. Contd. | ||