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).
Letter from H.D. Symons & Co. Ltd. detailing experiments with insulated aluminium foil for condenser work.
| Identifier | ExFiles\Box 52\3\ Scan052 | |
| Date | 3rd January 1922 | |
| X 4430. COPY OF LETTER RECEIVED FROM:- H.D. SYMONS & CO. LTD., INSULATION SPECIALISTS, ROYAL LONDON BUILDINGS, 196, DEANSGATE, MANCHESTER. 3rd. January, 1922. Messrs. Rolls-Royce Ltd., Derby. Dear Sirs, Further to our correspondence on the subject of insulated aluminium foil for condenser work, we have completed OUR EXPERIMENTS on this work and have pleasure in reporting to you as follows :- We have made a 25-yard length of aluminium foil and varnished silk from material that we had in stock, as near the dimensions in your specification as possible. We have used aluminium foil and varnished silk because we were of the opinion that it would give you the very best results for the following reasons :- 1) It will be easier to make your connexions to the aluminium foil. 2) The difference in strength between aluminium foil and paper is too great, so that the paper is inclined to break at the edges, merely on account of the strength of the aluminium foil. 3) The factor of safety to give the dielectric strength required would only be in the neighbourhood of 2 - 2½. 4) It would be difficult to get the dielectric inductivity you specify. As an alternative, to the use of the aluminium foil and varnished silk, it has occurred to us that winding varnished aluminium foil with an untreated cloth separator, which would afterwards be impregnated either with compound or air-drying varnish, might produce a condenser having sounder mechanical properties than the varnished silk and aluminium foil. We have therefore varnished a length of aluminium foil for you to try this process. Should this idea appeal to you. On the whole, we favour the use of aluminium foil | ||