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).
Examination report on the 'Bleriot Phi' cut-out instrument, detailing its construction and operation.
| Identifier | ExFiles\Box 48\3\ Scan159 | |
| Date | 6th December 1920 | |
| [Handwritten at top] X.4215 To R. {Sir Henry Royce} from EFC. {E. Fowler Clarke - Electrical Engineer} c. to CJ. c. to E. {Mr Elliott - Chief Engineer} c. to Da. {Bernard Day - Chassis Design} c. to By. {R.W. Bailey - Chief Engineer} c. to Bn. {W.O. Bentley / Mr Barrington} c. to EWT. for R.R.Inc. EFC {E. Fowler Clarke - Electrical Engineer} 1/T6.12.20. X.4215 - BLERIOT PHI CUT-OUT. [Handwritten] X 1815 We have had submitted to us for examination and test a cut-out known as "Bleriot Phi", made by Bleriot Ltd. This little instrument is rather well carried out, the magnetic circuit being on sound lines. The main contacts are of silver and of ample area, and they are supplemented by a light carbon contact for taking the break. The speciality of this instrument, however, is that it is provided with a subsidiary contact which breaks connection when the armature is drawn home, allowing an auxiliary compensating winding to be placed in series with the main shunt winding of the instrument. The scheme of connections of this instrument is shown in the accompanying diagram in which, however, the auxiliary carbon contacts in parallel with the main contacts MC, are omitted as not being necessary for the explanation of the working. The diagram shows the instrument connected up to a shunt dynamo and battery. The cut-out is similar to an ordinary cut-out with the exception that the shunt winding Sh is a long shunt not merely across the dynamo as is usual in cut-outs, but across the series winding Se in addition. This enables the motion of the lever to be used to operate an auxiliary contact which inserts in series with the main shunt winding a second winding, which acts partly as a resistance and partly as an | ||