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).
Results of tests on three different armature windings for dynamos.
Identifier | WestWitteringFiles\W\May1931-August1931\ Scan109 | |
Date | 28th August 1931 | |
To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Pgt. c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. Hy.{Tom Haldenby - Plant Engineer} ORIGINAL HS{Lord Ernest Hives - Chair}/Pgtl/AT28.8.31. X6099 X6126 DYNAMOS. In connection with the suggestion in N3/M24.6.31 of having three armatures made giving three stages of saturation of the armature teeth, we now have result of three armatures made on the lines indicated in that memo. These armatures were made from cores of the 24 slot type as present standard, the details being as follows :- 1. Wound with 5 turns per coil of 18 S.W.G. wire, the width of the tooth at the root being .160". 2. The slots were enlarged and the tooth width correspondingly reduced to .120". The winding was of 5 turns per coil of 17 S.W.G. wire. 3. In this armature the slots were still further enlarged reducing the tooth width to .085". These slots represent the largest it is possible to have with the present size of core, the limit being the mechanical strength of the tooth at the root. This slot was not large enough to accommodate a winding of 5 turns per coil of 16 S.W.G. wire, so that 17 gauge wire was again used with extra leatheroid packing. From the attached sheet of performance curves it will be seen that armature 1. gives an earlier cutting in point but is lower on the peak and more sharply controlled than either of the others. The rise in the peak from 1. to 2. rather confirms your remarks in paragraph 4 of the above memo to the effect that the nett result of increasing the copper would be to lower the temperature of the machine. Curve 2. shows that for the same temperature, we get a higher output with a tendency to keep up better at high speeds. The effect of reducing the width of the tooth alone is to make the cutting in point later, but at the same time give a slight increase on the peak and a slightly flatter curve. This is particularly shown by curves 2. and 3. | ||