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).
Comparison of Bosch and Watford armature windings, including diagrams and analysis of materials and construction.
| Identifier | ExFiles\Box 65\3\ scan0311 | |
| Date | 22th August 1928 guessed | |
| -2- Contd. If the Watford section was made more circular or oval, little or none of the iron section would be lost, but the dimension A would be shorter and thus more wire could be got on the core in the present available space. Comparing the windings it was observed that the Bosch was nicely tapered and the available space efficiently filled up, whereas the Watford windings were very flat with no room endwise for further winding, hence our suggestion re-core section - [Diagrams of Bosch and Watford winding cross-sections] Upon unwinding the Bosch armature it was found that the top three or four layers were of 44 S.W.G. enamelled copper-nickel alloy wire (presumably Eureka); we are not quite clear as to why this has been done, unless it is an ingenious effort to reduce the possibility of corrosive action caused by coronal discharges due to the windings passing in close proximity to the pole shoes; this alloy being less susceptible to corrosion than copper. The secondary winding was very closely wound with 44 S.W.G. enamelled copper wire (with the exception above) and neatly tapered, the tapering being more rapid towards the last layers. The primary winding, which occupied more than 60% of the total winding space, consisted of six layers of 21 SWG. enamelled copper wire, each layer insulated with a layer of oiled linen. We have not unwound an EW6 armature yet, and so are unable to state what proportion of space the primary occupies. Generally speaking, therefore, both as a result of tests and observations, we are of the opinion that the Bosch armature is the better of the two, both constructionally and electromagnetically. EFC/H.E.West. | ||