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).
Continued report on the electrical operation and component analysis of a dynamo, regulator, and switch system.
| Identifier | WestWitteringFiles\F\January1921\ Scan30 | |
| Date | 21th January 1921 | |
| Contd. -3- regulator armature arm when this is drawn into the extreme upper most position. From this point onwards electrically the circuit passes through a shunt winding and is then brought to the outside to be earthed. Thus it appears that in ordinary operation the resistance through the carbon granules is varied by the operating voltage so as to affect the field current in such a manner as to keep this operating voltage fairly constant. The function of the series coil would appear to be, that if for any reason the armature comes right home, an alternative path for the operating current through the carbon granules instead of through the shunt coil is provided, and the resis- to earth is then only composed of the series winding and the carbon granules, so that the dynamo excitation is reduced to a low value and will not keep the cut-out closed to charge the battery. This condition of affairs we have found to occur when the switchbox is not used in an upright position. We have just started the test and already arrived at the above, but the complete report of the actual operation on the bench will be sent later. When the above mentioned condition does occur, the dynamo is operating at about 2 volts, but giving quite a large current and we find that the regulator heats excess- ively. We have not so far arrived at the exact reason why this ring is necessary. (8) On the dynamo there is, in addition to the main field winding of about 4 ohms, a winding of about 175 ohms connected permanently across the brushes and in opposi- tion to the main field winding. Here again we have not yet arrived at the exact reason for the existence of this winding. (9) On examination of the moving contacts of the dynamo-battery switch it appears at first sight that four contacts are connected together and we were at first deceived by this. The division between the two pairs, however, is concealed by the fastening of the third pair of moving contacts of this switch. On our diagram the insulating mechanical connections between the various switch connections are represent- ed{J. L. Edwards} in full. (10) The lighting switch provides three position, the first one feeding 7 and 8, the second one 6, 7 and 8 and the third one 6 & 8. This would thus provide for side and tail, head and tail, or head, side and tail. Terminals 4 and 5 appear to be spare connections. (11) The resistance of the shunt coil both on regulator and cut-out is 57.3 ohms. The resistance of series coil on the cut-out is .105 ohms and that of the series coil on the regulator .076 ohms. Contd. | ||