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).
Investigation report on a faulty coil, number 3931, from chassis 42-EM.
| Identifier | ExFiles\Box 46\3\ Scan242 | |
| Date | 25th November 1924 guessed | |
| EFC. WA.{Mr Wallis}94. INVESTIGATION OF FAULTY COIL NO. 3931 EX CHASSIS 42-EM. When first received this coil exhibited the usual signs indicating a break in the secondary winding, i.e. the continuity of the windings could not be demonstrated on the A.C. supply with a 4 volt lamp placed across the primary. When placed however in series with a milli-ammeter and the supply voltage the apparent break almost immediately made and a reading of 14.7 milliamperes was obtained on the instrument. The continuity after this on the A.C. test was found to be O.K. The coil was then run for a considerable time on our standard ignition rig with a view to showing up the fault, but although the H.T. sparking at 6 volts was very bad, a definite failure of the coil could not be demonstrated even after the coil had been open circuited considerably. The running current at 12 volts was observed to be low .75 amperes (production limit .90). From the above observations the fault appears to be due to an intermittent break in the windings, probably at the junction of the two windings, and has functioned alright owing to the fact that charring has taken place, thus providing a high resistance path for the current. EFC/HEW. | ||