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).
Extended bench test of a Scintilla voltage regulator.
| Identifier | ExFiles\Box 166\2\ img035 | |
| Date | 13th May 1936 | |
| To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to BY.{R.W. Bailey - Chief Engineer} Y 6092 Hs{Lord Ernest Hives - Chair}/Wst.10/MJ.13.5.36. SCINTILLA REGULATOR. We have carried out on the bench an extended test of the latest Scintilla voltage regulator suitable for use with the type of dynamo used on our chassis. This regulator is designed on the multi-stage resistance principle, i.e. field resistance is inserted in gradual stages the number of stages being four. We originally criticised the unit, regarding its size, which we thought cramped the arrangement of design; also there was no proper adjustment for the contacts. It is satisfactory to notice that in the latest edition which we obtained last week these two points have been cared for. We have always considered, however, that the principle of gradually inserting the field resistance is right and must make the regulator fundamentally more reliable and smooth in operation. The first test made was to ascertain the temperature rise of the resistance and the highest temperature noted under the worst conditions of running was 87 C. It is considered, however, that this temperature will rarely be met with in actual practice due to the fact that the temperature referred to above occurred when the first stage resistance only was inserted. Under actual running conditions it will be almost impossible for the regulator to operate in such a manner. The regulator was then run on endurance test a total of 150 hrs. under conditions of open circuit dynamo voltage. Open circuit conditions ensured the regulator working at its maximum voltage (about 16 volts) which in turn meant maximum current in, and heating of, the resistance, and also maximum sparking at the contact points. The running was divided into three periods of 50 hours each. The first period at speeds between 1800 to 2000 RPM., the second at speeds between 2500 and 2700 RPM, and the third at speeds between 3300 to 3500 RPM. This variation in speed was necessary in order to bring into action all the resistance stages with their corresponding contacts. During the whole of this running practically no sparking could be observed at the contacts and, as anticipated, when examined at the end of the test the amount of contact wear was found to be negligible. This means obviously that the regulator is much less likely to get out of adjustment and consequently should be more reliable than our existing regulator. | ||