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).
Two types of very small synchronous motors, their specifications, and pricing.
| Identifier | ExFiles\Box 61\2\ scan0043 | |
| Date | 17th July 1929 | |
| Hs.{Lord Ernest Hives - Chair} from EFC. X75. EFC1/AD17.7.29. SYNCHRONOUS MOTORS. It is now possible to obtain very small power alternating current synchronous motors with incorporated reduction gear-ing, which motors are self-starting and synchronising when switched on to 200 volts 50 cycles. These are made up in two forms :- Type 'B' is arranged for final spindle speed of either one revolution per second or one revolution per minute, and its power is 1/200,000 H.P. Type 'C', a rather larger motor,is arranged for final spindle speed of 1 r.p.m. and its power is 1/10,000 H.P. The catalogue price of type 'B' is £3.10.0. and that of type 'C' is £4.17.6. You will appreciate the varied uses of small motors of this type, resulting from the fact that holding as they do a speed absolutely in step with the main supply generators, they are very useful for small apparatus which must run at constant speed. I am giving you this information as there may be cases in the experimental dept. in which a motor of this type would be very useful, particularly as the easy starting difficulty has been overcome. EFC. | ||