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).
Temperature tests conducted on the primary windings of ignition coils for 40/50 and 20 HP chassis.
| Identifier | ExFiles\Box 69\1\ scan0241 | |
| Date | 6th October 1929 | |
| Ry. from EFC. c. Hs.{Lord Ernest Hives - Chair} c. Hs{Lord Ernest Hives - Chair}/AJL. c. Ry/RD. X8710 EFC2/AML6.10.29. X4501 TEMPERATURE TESTS ON THE ROAD OF PRIMARY WINDINGS OF IGNITION COILS ON 40/50 AND 20 HP CHASSIS. In this connection may we remind you of a report EFC4/T2.11.28 describing the results of a series of tests with a view to comparing the heating of an ignition coil, both externally (coil not working) and internally (coil working) on both the 20 HP. and 40/50 HP. chassis on which the coil positions are different and somewhat more favourable as regards coil temperature in the 20 HP. case. The primary temperatures reported in EFC4/T2.11.28 as having been found on the road for the four cases considered were 20 HP. coil not working 56°C. " " working 93°C. 40/50 HP. " not working 66°C. " " working 120°C. We have now to hand similar results for one of the L.C. type coil incorporating larger iron core and larger gauge primary winding (21 SWG). Also the secondary winding wound on a paxolin tube over the primary. As in the previous tests the primary winding temperature was observed by an increase of the electrical resistance when the coil had been warmed up by heat conduction and radiation only from the engine without itself working (the engine being run on magneto), and secondly with the coil additionally warmed up/running the engine normally on the battery ignition. Also as in the previous test, the car was run for one hour in the first set and for 1 1/2 hrs. in the second set, the radiator water temperature in each case, being maintained at 95°C. The results observed for the primary winding temperatures were as follows :- 20 HP. coil not working 54°C. " " working 84°C. 40/50 HP. " not working 65°C. " " working 100°C. | ||