Comparison of dynamo control methods, specifically regarding the performance of the control brush.
| Identifier | WestWitteringFiles\G\June1921\ Scan105 | |
| Date | 22th June 1921 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 2/T22.6.21. variation in the exact bearing of the control brush on the commutator. The brushes appear to be bedding well, nevertheless some amount of pressure put upon the control brushes temporarily, and afterwards removed, seems to improve the performance of the machine. The point made by the Lucas Co. against the use of the single field winding third brush controlled machine is that the control brush gives trouble in service owing to the fact that it has to deal with relatively heavy field current at a comparatively low voltage and hence variations in the control brush bedding affect the output of the machine materially. It is contended that the Lucas method of control avoids this trouble. Our experience with this machine, however, shows that it does not altogether avoid this trouble, in fact one would have thought, owing to the control brush, having to deal with a still heavier current at a still lower voltage, that what extra stability was gained by the use of this additional winding in conjunction with a main field winding across the main brushes, would be lost on the average effect in the excitation. The method of control on the Smith dynamo seems to suffer the least from this defect, perhaps partly due to the fact that the control is duplex. We made a heating test on this lengthened Lucas machine at the constant output 9 amperes at 14.6 volts. Contd. | ||
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).