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).
Test report on the suitability of a field resistance for a 40/50 high output dynamo.
| Identifier | ExFiles\Box 163\6\ img023 | |
| Date | 24th March 1930 | |
| COPY. X6016 EFC. P.D.48. March 24th, 1930. X.6016. X.6004. FIELD RESISTANCE FOR 40/50 HIGH OUTPUT DYNAMO. Tests have been made to determine the suitability, for use in conjunction with the 40/50 high output dynamo, of the resistance adopted for connecting in the field circuit of the 20/25 high output machine. This resistance, as specified, consists of 3'6" of bare 26 SWG. Eureka wire, and a similar resistance, but made up of double cotton covered wire, was made up for trial. The machine used was high output dynamo IO.1.M. having an output peak of 15.0 amperes. In the same hot condition (80oC.) inserting the resistance reduced the peak to 8.7 amperes. An output curve was taken with the resistance in circuit. In order to ascertain to what extent the resistance heated up, the machine was run for half an hour under conditions such as to give the maximum possible field current, i.e. starting cold (18oC.) and working on schedule volts, the machine was run at a speed and output corresponding to the field current peak of 1.87 amperes. The resistance became too hot to keep in contact with the hand, and the cotton covering the middle portion was definitely discoloured. In ordinary service however, it is thought that the resistance would be quite safe. CAP. | ||