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).
The regulation of field current in a system using vibrating contacts to insert resistance into the field circuit.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan207 | |
| Date | 2nd June 1926 | |
| EFCL/T12.6.26. -7- Contd. The well known examples of such systems are those in which regulation of the field current is brought about by periodically inserting into and withdrawing from, or varying whilst inserted, a resistance in the field circuit, in the former case by means of vibrating contacts which tend to open when the combined voltage and current function reaches a certain prearranged value. The moment it does so the resistance is inserted and the function then tends to decrease, so that the result in that case is a continual vibratory regulation of the amount of current actually flowing through the field winding. The windings which supply electro-magnetically the necessary force to insert and withdraw or regulate the field resistance will comprise a volt winding and an ampere winding having a magnetising effect on the same core, and the proportions of these windings may be arranged such that for example the magnetic force is sufficient to take effect when the quantity V + .25A where V is the operating voltage of the system, and A the ampere output of the dynamo, reaches a prearranged value, say 17. Then, with the dynamo on open circuit the voltage of the system will be 17 and when the dynamo is supplying 12 amperes the voltage of the system will be down to 14. Contd. | ||