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).
Analysis of performance curves and irregularities caused by carbon contacts in a regulator.
| Identifier | ExFiles\Box 31\1\ Scan084 | |
| Date | 1st October 1920 | |
| Contd -3- EFC6/T1.10.20. There are also two further curves for the controlled condition determined by operating upon special characteristics (c) and (d) for the cold and hot condition respectively. Comparing these two groups of curves it will be seen how much the output is reduced when the operating voltage is caused to be greater by the characteristic of the battery circuit. It will also be seen that in both groups whereas the current delivered in the hot condition is less than for the cold condition when the speed is low ( due to the operating voltage being higher), it is greater for the hot condition than for the cold at the higher speed, in spite of the operating voltage still being higher. This phenomenon is, of course, due to the operating coils of the regulator being heated up and causing less resistance to be inserted in the field circuit, due to the smaller current taken by these coils, even though the voltage be higher. Approximate curves of field current in the four cases are also given. It will be noticed that all the curves given for the controlled condition, including those previously issued for open circuit, are somewhat irregular. We have now found that most of this irregularity is due to the carbon contacts, on one of which little mountains of carbon are formed, corresponding to depressions in the other. The variation in these formations is continually altering the amount of resistance interposed between the contacts corresponding to a given current in, and therefore pull of, the windings and we Contd. | ||