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).
Correspondence discussing the M.A.X.E.I. patented process and the use of synthetic varnishes for impregnating windings.
| Identifier | ExFiles\Box 24\2\ Scan292 | |
| Date | 19th March 1928 | |
| -5- Contd. I am not surprised that the patents covering the admission of oxygen or ozone during the impregnating process were allowed to lapse, as I consider this to be most undesirable. The M.A.X.E.I. patented process mentioned in my article consists in the complete separation of two distinct operations of evaporation and oxidisation, in such a manner as to carry out the evaporation rapidly but without fear of oxidisation, and finally to oxidise the varnish rapidly and thoroughly even to the centre of the winding, by regulating suitably the admission of air. Windings treated in this way will be immune from the harmful action of hot oil. March 7th. 1928. (sgd) A.C. Dunlap. "Having had occasion in previous correspondence to question the somewhat extravagant, if not fantastic, claims made for synthetic varnishes worked by the M.A.X.E.I. process, the writer was not surprised to see in your issue of the 16th inst. an admission by Mr. Dunlap that he had "made no attempt to treat exhaustively the whole subject". It is difficult to understand the necessity for this complicated elaboration to attain results which are most easily and simply obtained by good-quality grease or oil varnishes in apparatus capable of being constructed with a little mechanical knowledge and the ordinary facilities of an engineering workshop. Synthetic resins are most useful, and have a very wide field of application in the form of moulded articles and built-up insulation generally, but as a medium for impregnating windings they are decidedly undesirable; the best testimony to this is the fact that they have been completely abandoned for such purposes in America, and the same state of affairs is fast approaching consummation in France. British manufacturers who are now called upon to build plant and apparatus (particularly transformers) for extreme high pressures, and large outputs, would be well advised to institute enquiries as regards the experience of the two countries named, if they would wish to avoid the troubles which have ensued from the use of synthetic varnishes. N'ampton March 19th.1928. (sgd) C.W. Crosbie. | ||