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).
Performance of a dynamo-battery system, generator cut-in speeds, and the use of compound versus shunt windings.
| Identifier | ExFiles\Box 57\1\ Scan052 | |
| Date | 9th December 1930 | |
| X5780 EFC. from PN.{Mr Northey} c. R.{Sir Henry Royce} Sg.{Arthur F. Sidgreaves - MD} E.{Mr Elliott - Chief Engineer} c. Mx.{John H Maddocks - Chief Proving Officer} Wor.{Arthur Wormald - General Works Manager} c. Da.{Bernard Day - Chassis Design} Ev.{Ivan Evernden - coachwork} c. Hd.{Mr Hayward/Mr Huddy} EP.{G. Eric Platford - Chief Quality Engineer} PN{Mr Northey}20/GDL9.12.30. X.8780 X.5780. PERFORMANCE OF DYNAMO-BATTERY SYSTEM X.3374. Referring to your EFC2/AD9.12.30 and your EFC1/AD12.12.30. Am I right in assuming that the switching proposition you have proposed in the latter memo will enable the generator to cut-in at 15 or 16 m.p.h. if desired? I have in the past, more than once, wondered why we did not make use of a compound winding instead of a pure shunt machine. The suggestion made by R.{Sir Henry Royce} recently to include the head lamps in a series winding appears to me very valuable, and I am anxious to hear what may have proceeded on these lines in view of this proposal. I get the impression in your first memo that in places you wrap up in unnecessary mystery the behaviour of a shunt wound generator in conditions of service on one of our cars; in other words, a dynamo having to do its work through a wide variation of speeds. One would think from your memo that the output of a generator must increase merely as a result of being coupled to a number of cells across which the P.D. is capable of rising. You do not point out that thisphenomenon is only found as a result of the speed of the generator being able to increase. If the speed of the generator were kept constant, its load when charging a given battery at a given temperature, would gradually fall off, because of increase of back E.M.F. until you got to the point, in the absence of an automatic cut-out, when the battery might discharge into the generator if anything happened to cause the P.D. of the latter to fall. I merely have taken the trouble to dictate the above in view of such paragraphs as the 2nd. on page 3 of EFC2/AD9.12.30. PN.{Mr Northey} | ||