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 voltage breakdown performance of a battery ignition mushroom type H.T. rotor.
| Identifier | ExFiles\Box 61b\2\ scan0107 | |
| Date | 19th April 1929 | |
| EFC. WD.{Mr Wood/Mr Whitehead}55. 19.4.29. BATTERY IGNITION MUSHROOM TYPE H.T. ROTOR We have now tested four of these rotors moulded by Mr. Brock with extra thickness in the crown. We found that the voltage breakdown figure was considerably increased, being now in the region of 19000 volts R.M.S. instead of 12000 volts R.M.S. as previously (see WD{Mr Wood/Mr Whitehead}53 of the 12th inst.) All the four rotors tested withstood successfully for 5 mins, 18300 volts R.M.S. applied between the cam and rotor blade. As the voltage was raised above this figure they began to break down, two after one minute at 18800 V.{VIENNA} R.M.S. and one after one minute at 19100 V.{VIENNA} R.M.S. whilst the other successfully withstood 19400 volts R.M.S. for one minute. These results are very satisfactory and show that this modification to the crown thickness has improved the electrical breakdown figure over 50%. We have also tested four other rotors with the standard thickness after having been well baked and these show a 25% improvement, the average breakdown figure being 16000 volts R.M.S. It would seem advisable if at all feasible to well bake all our bakelite mouldings which are used for H.T. work. EFC/H.E.West. | ||