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).
Specifications and suitability of a variable speed 3 B.HP motor from Crypto Electrical Co. Ltd.
| Identifier | ExFiles\Box 61\2\ scan0037 | |
| Date | 26th July 1928 | |
| To Hy.{Tom Haldenby - Plant Engineer} from EFC. X2065 EFC4/T26.7.28. VARIABLE SPEED 3 B.H.P. MOTORS. We have perused the attached letter from The Crypto Electrical Co.Ltd., and confirm your pencil note thereon that we do not require the no-load and over-load release fittings. On our present equipment we get along quite satisfactorily without any such items as the fuses on our supply board will do all that is required in the way of protection. We note that they offer a regulator operated by a single handle passing over 28 stops total of shunt and series control. This might be of more convenience in some ways but it does not offer quite the same degree of adjustment as independent armature and field winding controls, the combination of which controls is a very useful feature on our present equipment. We should like them to offer quite independent and perfectly plain (i.e. no auto devices, springs, etc.) rheostats which are each capable of remaining in position on any stop so that any combination of two positions may be utilised. The reason is that those who use this motor would appreciate the manner of its functioning and that therefore the additional complications are not necessary as they would be when the machine is to be operated by anyone who happens to come along. We think that if they can supply rheostats as suggested the cost of the equipment might be considerably less than the complete equipment which they specify. EFC. | ||