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 a 20 HP Dynamo Output Controller.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 26 | |
| Date | 11th November 1926 | |
| AC.79. 11.11.26 20 HP. DYNAMO OUTPUT CONTROLLER. One of these units (marked 1182) has been adjusted and tested for use on a 20 HP. chassis. The instrument was connected to a standard dynamo charging a battery and with a starting temperature of 17°C, was adjusted to open at 14.5 volts. It was then found to close at about 8.0 volts. Next a voltage of 17.0 was applied to the shunte coil and maintained until final temperature conditions were reached. The voltage to open was then observed to be 16.3 and to close, 9.0. All the above figures were slightly lower (about .2 volt) if taken with the dynamo on open circuit owing to undulations in the voltage, which the voltmeter could not follow. The controller was now incorporated in a standard 20 HP. charging circuit using an Exide battery. When the battery was not fully charged, the dynamo could deliver its peak output, without the opening of the controller contacts; as the voltage of the system rose, the points opened and reduced the charge. With slow rises of voltage the controller was apt to insert the field resistance by an infinitesimal movement of the armature, the consequent reduction in the system voltage preventing it from completing its travel. A slight flexibility seems to be required in the contact point mounting, so as to allow a definite travel of the armature before separating the points. A very slight vibration, however, was found to be sufficient to send the armature right over, once it had started. A demagnetising current of about 3.0 amperes in the series coil of the controller, representing a headlamp load was found to be ample to throw the switch back into the closed position. EFC/F.J. Allen. | ||