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).
Fitting and performance of a 20 HP dynamo with a higher output armature.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan104 | |
| Date | 25th July 1928 | |
| To R.{Sir Henry Royce} from EFC. c.c. EJ. EFCL/T25.7.28. 20 H.P. DYNAMO ARMATURE OF HIGHER OUTPUT. As previously reported it has been arranged for the 20 H.P. dynamo with coarser higher output armature to be on your 'India' chassis. There will, in line with this higher output machine, be also the green lamp switch and green lamp. It has occurred to me, however, that possibly you might not wish to have this higher output machine on this car because such higher output is only really intended for particular clients who require a large output on long night runs. There will, however, be a new P & R.{Sir Henry Royce} battery on this car so that if we regard it as a test on the dynamo only we shall not be so likely to be in trouble with the battery through overcharging. The actual peak output of the dynamo in normal operation and in a given temperature condition varies considerably with the P.D. which the condition of the battery and system cause to exist across the dynamo terminals. We have found that the peak output is almost exactly proportional to the terminal voltage on the dynamo. Having added 1-1/4 amperes of ignition current to the observed peak output as given by the ammeter, the result may differ from the 15-1/2 amperes shown on our curve for the 80°C. condition of the dynamo, insofar as the voltage existing across the dynamo terminals differs from the 18.4 corresponding to 15-1/2 amperes on our sheet. The operating voltage, if measured, will be found to be (always for the same temp. condition of the dynamo) proportional to the output observed. | ||