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).
Requesting experiments on partial temperature compensation for an auto charge control switch using Eureka resistance wire.
| Identifier | ExFiles\Box 59\1\ Scan266 | |
| Date | 13th February 1928 | |
| X4008 To BY, from EFC. c. BY/RD. EFC3/T13.2.28. AUTO CHARGE CONTROL SWITCH. We want to make experiments on partial temper-ature compensation of the auto charge control switch by the use of Eureka resistance wire wound on in the space at present occupied by packing. This new winding to be put in series with the main shunt winding. For this purpose the main shunt winding must be of coarser gauge. What we would like to have instructed for this experiment is two main shunt winding bobbins duly wound one with 34 SWG. DSC. wire and another with 32 SWG. DSC. wire, the number of turns in each case to be such as to fill the winding space exactly as with the present 36 SWG. DSC. wire of which there are 2800 turns. We shall then make the experiment of winding on on the other bobbin Eureka wire of varying gauge, length and number of turns, until we find the suitable amount that will give the same operating voltage. We hope by this means to arrive at a suitable combination of Eureka resistance wire winding on the one leg in series with copper wire winding on the other leg, which combination will have a much smaller temperature coefficient than the copper by itself and will thus improve the operation of the auto switch, of which the chief defect at the moment is the rapid increase of shunt voltage with temperature. Would you kindly have instructed two such shunt winding bobbins with the two gauges of wire specified and handed to us for the purpose of these experiments. EFC. | ||