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).
Analysis of the Bleriot Phi Cut-Out, focusing on the functionality of its compensating winding.
| Identifier | ExFiles\Box 48\3\ Scan171 | |
| Date | 22th December 1920 | |
| To Wd. {Mr Wood / Mr Whitehead} from EPC. c. to Da. {Bernard Day - Chassis Design} X.4215 EFC {E. Fowler Clarke - Electrical Engineer} 2/T22.12.20. X.4215 - BLERIOT PHI CUT-OUT. The makers' principal claim with regard to the superiority of this cut-out over others, is that the addition of the compensating winding overcomes the necessity of a reverse current from the battery to cause the cut-out contacts to fall apart. It does not, however, do this completely, but only reduces this current. Reverse current for cutting out can be minimised, apart from any compensating winding, by suitably designing the cut-out with proper reference to the variation of the spring tension and magnetic traction (for given ampere turns) with gap. A good magnetic circuit (with its attendant advantage of fewer watts expended on the shunt coil during operation) necessarily has a rapidly increasing magnetic traction with reduction of gap and so the compensating winding permits of the use of such a magnetic circuit by reducing the reverse series amperes from the abnormal value which would naturally result to a value more usual in ordinary cut-outs. We agree with the makers that the advantage of less heating and consequently less change of operating Contd. | ||