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).
Preliminary experiments comparing stamped slotted armature plates with milled slotted plates for shunt dynamos.
| Identifier | ExFiles\Box 62\3\ scan0388 | |
| Date | 28th August 1933 | |
| 86142 To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. C.c. BY.{R.W. Bailey - Chief Engineer} Wor.{Arthur Wormald - General Works Manager} C.c. Ph. C. Hs{Lord Ernest Hives - Chair}/Wst. 7/KT. 28. 8. 33. SHUNT DYNAMO ARMATURES WITH STAMPED SLOTTED PLATES IN PLACE OF MILLED SLOTS. We have conducted preliminary experiments with a 40/50 shunt dynamo fitted with an armature assembled with "Stalloy" iron plates with slots stamped before assembly. Our usual practice is to assemble the plates and mill the slots afterwards, but as we have previously pointed out, we consider the milling of the slots must negative the effect of using laminated plates in the armature. We proved that with the milled slots as at present, there was a considerable iron loss in the armature core as shown in a considerable reduction in the available output the machine would give, for a safe temperature rise, at high speeds, as against that obtained at low speeds. For instance in one particular machine whereas 14 amps. could be obtained at low speeds for a given temperature rise, only 10 amps. could be obtained at high speeds, i.e. 5000 r.p.m. The first armature we have tried with the stamped slotted plates gave very encouraging results, and we obtained a drop of only .6 amps. between low and high speeds, showing that the iron losses in the armature core have been considerably reduced. We are now trying a further armature using "LOHYIS" stamped slotted plates instead of "Stalloy" but we do not anticipate that this material will give us any better results at high speeds, probably somewhat worse, but the cutting-in speed of the dynamo may be improved. We will arrange to report further results of tests on both armatures later. Hs{Lord Ernest Hives - Chair}/Wst. | ||