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).
Test report on the current required to operate and de-operate various electrical cut-outs.
| Identifier | WestWitteringFiles\D\March1920\ Scan36 | |
| Date | 1st March 1920 | |
| Contd. -2- Ck{Mr Clark}4/T5.3.20. Then it was arranged to send a reverse current through the series coil and adjust this to such a value that with current passing through the shunt coil of magnitude just sufficient to operate cut-out, the effect of the shunt coil was sufficiently neutralised to allow the contacts to fall apart. The following observations were obtained :- Cut-out. Current in shunt coil to just operate. Reverse current in series coil to de-operate. Lucas present standard A.{Mr Adams} .345 4.5 Lucas present standard B. .42 6.1 Smith cut-out (1) .100 1.8 " " (2) .069 2.05 Subsequently, it being assumed and proved that the magnetic effect of the cut-out for a given current is independent of temperature (although of course the volts vary) it has been found what voltage is necessary to pass the amount of shunt current tabulated above after heating up the cut-out by means of the application of a 16 volt battery to its shunt coil for a period of 30 minutes, with the following results :- Cond. | ||