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).
Recommendations for improving the S.R. Cut-out by redesigning the magnetic circuit.
| Identifier | ExFiles\Box 168a\3\ img143 | |
| Date | 25th January 1935 | |
| -2- Hw/Wat.5/M.25.1.35. Cont'd.{John DeLooze - Company Secretary} These results show that considerable improvement in the operation of the S.R. Cut-out can be obtained by redesigning the magnetic circuit and our recommendations are as follows :- (a) Substitution of the iron coil flanges for non-ferrous ones. (b) Increase in iron section of the base plate and armature. (c) Increase in coil core diameter. This can be done at the expense of winding space, this being more than is necessary at present for sufficient magnetization. (d) Decrease of air gap between series pole face and armature. (e) Increase in section of copper flexibles between armature and pole core. (f) Larger contact area. We should aim at the shunt coil doing all the work in regard to operating the cut-out and holding it in, with sufficient pressure, the series coil supplying extra contact pressure as the charging current increases. To reduce volt-drop due to heating of the points. For this to happen the magnetic circuit should not be saturated by the shunt coil magnetization, the saturation point being reached when say a current of 10 to 15 amperes is flowing round the series coil in addition. In order to reduce the total volt drop across the cut-out the series coil winding gauge should be increased to reduce its resistance. At the same time the number of series turns could be reduced without affecting the "cutting out" operation of the unit. We consider that the modification of our cut-out on the lines indicated above will considerably improve its operation with a voltage controlled system and obviate the troubles which have been experienced. HW/Wat. | ||