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).
Report concluding tests on the effects of earthing H.T. windings on spark energy and misfiring.
| Identifier | ExFiles\Box 52\3\ Scan333 | |
| Date | 18th October 1919 guessed | |
| -4- Contd. however, i.e. when secondary terminals connected as above definite misfiring occurred, when the running current (at 500 R.P.M. of "timer") was reduced to 1.37 amps. as compared to 1.30 amps. when H.T. terminals are connected in the way indicated on the coil box tending to shew that had the "ground" terminals end of H.T. winding been as well insulated from the rest of the coil as the designed H.T. terminal end of winding, sparking would have been as good whichever H.T. terminal was "earthed" provided that current direction is reversed. "Method of "earthing" of the H.T. winding did not affect the above. Conclusion. The above tests would shew that in a coil in which one end of the H.T. winding is "earthed" the spark energy is greater when the current in primary is in a given direction. Provided the insulation of H.T. winding is uniform throughout with respect to other parts of the coil; which terminal of the H.T. winding is "earthed" does not effect the spark energy so long as, when changing the "live" terminal over to "earth" the primary current is reversed in direction at the same time. Whether the "ground" terminals of the H.T. winding is "earthed" direct, or through a part of the L.T. circuit does not seem to have any effect. (It would seem that in a H.T. winding, one end of which is earthed, the spark energy is effected by direction of motion of electrons with respect to "live" electrode of the spark gap). (Sgd) R.G.Jamie. | ||