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).
Test report on the behaviour of a 20 HP dynamo when excited but unloaded.
| Identifier | WestWitteringFiles\K\September1923\ Scan80 | |
| Date | 28th September 1923 | |
| To R & E.{Mr Elliott - Chief Engineer} from EFC. c. CJ. & PN.{Mr Northey} c. DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} c. WOR.{Arthur Wormald - General Works Manager} OY. DB{Donald Bastow - Suspensions} ORIGINAL EFC5/T28.9.23. X.4383 - BEHAVIOUR OF 20 H.P. DYNAMO EXCITED BUT UNLOADED. A short test has been made on the effect of running of the 20 H.P. dynamo with the exciting winding connected, but without any external load. The machine, having been set in accordance with the standard production test, was then arranged to be as far as possible heat insulated on the testing rig, and was warmed up to a carcase temperature of 80°C by running on the ordinary battery load. Open circuit volt-speed readings were then taken at various speeds up to 2000 R.P.M. - the highest speed obtainable owing to the large self-load - and the/carcase temperature varied from the 80°C to 90°C during the readings. Voltages across the main brushes and also between the main positive brush and the control brush, i.e. across the field winding, were observed, also the excitation amperes, which are tabulated below. It will be understood that the temperature range referred to of 80° to 90°C was merely the/carcase temperature at which the readings were taken and that the machine, if allowed to run continuously in this condition would, as observed, rapidly rise in temperature and burn itself out at the higher speeds. For instance, at 2000 R.P.M., in the field winding there would be being dissipated at 90°C as much as 410 watts. Co... | ||