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).
The examination of a faulty dynamo and cutout, identifying a bent contact spring as the cause of over-voltage.
| Identifier | ExFiles\Box 57\2\ Scan041 | |
| Date | 25th June 1927 | |
| To BY.{R.W. Bailey - Chief Engineer} from EFC. c. SFT{Mr Swift}/Mr.Brock. X5783ch EFC2/T25.6.27. 20 HP. DYNAMO 1739 AND CUTOUT 1462 EX CHASSIS GSK.38. We have now examined this dynamo and distribution box. From our inspection we judge that the initial fault in this instance has been due to the fact of the cutout moving contact spring support having become bent upwards in such a manner that on the armature going completely home to the poles, effective contact has not been made, when the cutout was heated by the shunt coil, and even not properly made when cold. The condition of the shunt coil of the cutout is such that over-voltage on the system must have existed. This over-voltage would be accounted for by the incorrect cutout action of the dynamo and the battery. We can only think that what Mr. Brock suggests is correct, viz. that the cutout contact spring has had its natural shape either intentionally or unintentionally altered. A new cutout shunt winding will clearly be necessary. We herewith send apparatus to BY.{R.W. Bailey - Chief Engineer} EFC | ||