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).
High iron losses in shunt dynamo armatures and a plan to test alternative stamped materials.
| Identifier | ExFiles\Box 62\3\ scan0351 | |
| Date | 9th May 1933 | |
| E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to Wor.{Arthur Wormald - General Works Manager} 86142. Hs{Lord Ernest Hives - Chair}/Wst.7/MA.9.5.33. SHUNT DYNAMOS. As referred to in conversation with you we are of the opinion that our dynamo armatures have high iron losses which we attribute largely to the armature slots being milled after assembly. In conversation with Mr.E.W.Richmond, director of Joseph Sankey & Sons., in respect to this, he confirmed our theory and was convinced that the whole advantage of the laminated armature in reducing iron losses was entirely negatived by our slot milling process. In order to test this fairly quickly we have arranged for two stamped slot armatures to be submitted to us for test in direct comparison with a milled slot armature. One of these armatures will be of Stalloy which has a reasonable permeability with exceptionally low hysteritic and eddy current losses, and the other of Lohys which has a good permeability but higher losses than Stalloy. As you will appreciate it will be a great help to us in improving our shunt machines if we can reduce heating effects at high speeds. With regard to the accuracy of the stampings, we think there will be no difficulty at all. The C.A.V. Bosch people are buying all their dynamo stampings from Sankey's who have recently installed new machinery of their own design in order to ensure absolute slot accuracy and exact register. Hs{Lord Ernest Hives - Chair}/Wst. | ||