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 results and electrical specifications for a controller, including shunt and series measurements.
| Identifier | ExFiles\Box 35\3\ scan 090 | |
| Date | 21th May 1926 guessed | |
| AC.74. -3- Contd. Controller. Shunt volts to pull over 16.2 " amps. " " .23 " volts back "on contact" 9.5 " amps. " " .137 " volts to re-break contact 11.5 " amps. " " .165 " volts right back 9.0 " amps. " " .130 Series amps. to pull over 29.5 " " back"on contact" 17.5 " " to re-break contact 21.0 " " right back 15.0 1.8 amperes in the series coil are thus equivalent to 1.0 volt on the shunt coil in magnetizing effect. The shunt winding of the two elements is of about 70 ohms resistance. All the foregoing figures are for a starting temperature of about 17°C, and with the base of the unit horizontal. The pull required on the armatures is increased about 2% when placed vertically. The resistance placed across the controller contacts has a value of 17 ohms with no appreciable temper- ature coefficient. This is too high for the 20 HP. R.R. dynamo, however, a value of about one tenth of this amount being more suitable. A test was made using the Midgley unit fitted with a 1.725 ohms controller resistance, a standard 20 HP. R.R. dynamo and a fully charged P & R battery connected up on standard chassis wiring. At about 6.0 amperes charge, the controller operating voltage was reached, and, maintaining the same dynamo speed after operation, the output fell to | ||