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).
Electrical failures related to coils and condensers in the 20 HP car.
| Identifier | ExFiles\Box 51\2\ Scan141 | |
| Date | 31th August 1923 | |
| Y4338 to WOR. {Arthur Wormald - General Works Manager} from EFC. {E. Fowler Clarke - Electrical Engineer} c. BY. {R.W. Bailey - Chief Engineer} EP. {G. Eric Platford - Chief Quality Engineer} EFC {E. Fowler Clarke - Electrical Engineer} 4/T31.8.23. RE 20 H.P. CAR. Y4338 With reference to the electrical portion of the 20 H.P. car reported in EP {G. Eric Platford - Chief Quality Engineer} 18/H13.6.23 and EP {G. Eric Platford - Chief Quality Engineer} 4/H24.7.23, our remarks with regard to the points raised are as follows, 7 & 8 being covered by the various items in par. 35.:- (35) (a) COILS. Failures of coils in stabalite cases have been in nearly every case due to insufficient insulation of the primary winding. This weakness has been seriously tackled and additional insulation has been introduced between the layers of the primary, particularly at the ends. At the same time we have developed an intensive test of primary winding, through which for the moment every primary winding is being put, previous to the addition of the secondary. This sets up a potential difference of 1500 volts between the terminals of the primary winding, and an insulation weakness will be broken down, - as we have actually demonstrated with one of the old primary windings without the insulation. This is an immediate improvement, but a still further improvement in the reliability of the coils will be ensured by the standardisation of the 1/2" longer coil in stabalite case, in which the 6-layers of primary winding have been reduced to 4, and the insulation of the primary wire will be enamel and single cotton covered, in place of double cotton covered. There is little no likelihood of this failure being a general one amongst all the coils that have gone out, as many of the primaries so wound have been subjecte to our test without breakdown. It is therefore considered unnecessary to take any retrospective action. (b) CONDENSERS. Condenser failures have been largely due to poor condenser connections. These have been improved considerably on the present design by slight change in the method of building, and additional care in assembly. At the same time a complete new design is going through in which the reliability of all the condenser connections is undoubtedly more assured. As regards the rise of capacity due to temperature, we very much doubt if this has actually been the cause of failure. We have on our own experimental cars proved that the condenser does not reach a temperature of 73°C. and at this temperature the capacity and leakage is by no means excessive. Experiments on these phenomena are still in progress. Contd. | ||