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).
Alterations to volt-ampere characteristics for hot and cold conditions.
| Identifier | ExFiles\Box 31\1\ Scan083 | |
| Date | 1st October 1920 | |
| Contd. -2- EFC6/T1.10.20. characteristics was given with our EFCl/T22.7.20. We have, however, now altered the characteristic for the hot condition in such a manner that the hot and cold characteristics now called A and B converge to the same voltage, namely, 15.6 at 16 amperes. Our new standard A and B characteristics are shown on the attached sheet. We also attach a further sheet of two special volt-ampere characteristics for hot and cold conditions which will be seen to converge to the same voltage 16.0 at 12 amperes out-put. In working to these characteristics a carbon plate resistance is used in the main battery circuit for the purpose of increasing the operating voltage above that of the battery, and when it is necessary to reduce the voltage of the battery, a discharge circuit is switched on which takes current from the battery. With these, it is possible in making the test to adjust the operating voltage to suit the particular ampere output at the time, and therefore to realise the equivalent of working upon a battery circuit of volt- ampere characteristic defined by our tables. Of the six ampere output curves shown, two are for the plain shunt condition cold, and at the highest temperature to which the machine could be warmed up on the bench (carcase about 35°C), these two curves being determined on the A and B characteristics. Corresponding to these, there are two curves for the controlled condition, one cold on characteristic A, the other hot on characteristic B. Contd. | ||