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).
Continued description of a method for obtaining high D.C. voltage for insulation testing using a valve, condensers, and a spark gap.
| Identifier | ExFiles\Box 39\3\ Scan275 | |
| Date | 29th April 1927 guessed | |
| -2- Contd. thing (battery included) may be self-raised to a high D.C. potential. The valve readily permits the flow of positive electricity from plate to filament (i.e. negative electrons from filament to plate) but acts as a dead stop to any reversal. Consequently it is possible with this unit to obtain a high D.C. voltage or to charge up a batch of condensers which may then act as a battery of very high tension and small capacity. The output may be applied to insulation testing in the manner indicated in the second diagram, in which an the milliammeter, shunted by a suitable condenser to prevent damage to the instrument in case of too rapid fluctuations, indicates the small current actually pushed through the insu- lating material. As a voltmeter a calibrated spark gap is utilised and the voltage estimated from the length of gap which will just permit a spark to pass over, while the pressure is applied to the insulation. A convenient means of supply of H.T. is an old type RR. trembler coil so connected (see diagram 2) as to render the H.T. impulses positive. If this coil be operated it is possible to obtain a stream of discharges of the condenser inside the rectifying unit, the condenser discharging across the spark gap each time it is full up to sparking voltage, the frequency of the discharges being considerably less than those of the trembler coil. On putting on a large H.T. condenser (.3 mf. suitable for 5,000 volts R.M.S.) C ontd. | ||