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).
Improved electrical testing methods for short circuits and insulation using transformers and Meggers.
| Identifier | ExFiles\Box 165\3\ img009 | |
| Date | 12th January 1920 | |
| Ck{Mr Clark}1/T12.1.20. -2- Contd. become short circuited. A better method of showing up short circuited turns, and one for which we hope, in the cases of the actuator box and main switch to recommend additional paragraphs on our specification of production tests, consist of making use of an alternating supply of definite voltage and frequency from a transformer, such as they already have, and ascertaining that the magnetising current of the apparatus falls within a certain limit. A single short circuited turn on any coil, which might be overlooked in the resistance measurement, would have a far greater effect on the current taken, and any serious number of turns short circuited will also be shown by the heating of such turns. For such tests a small inexpensive ammeter reading 0 to 6 amperes will be required. We hope to give you particulars later. The Megger recommended should be used, although we have not everywhere previously stated this, to measure the insulation of the windings of all the apparatus with windings that is turned out. It will also be used during the process of armature winding to ensure that there is no fault or bad spot in the first layer of conductors before the second layer is put into place. We return herewith Messrs. Eversheds catalogues. If you obtain a 500 volt 0 to 100 megohmmeter for the Contd. | ||