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).
Letter from Everett, Edgcumbe & Co Ltd discussing the performance of Warren Synchronous Motors under variable frequency and voltage.
| Identifier | ExFiles\Box 165\4\ img065 | |
| Date | 23th May 1930 | |
| X 6023 ON ADMIRALTY. WAR OFFICE AND INDIA OFFICE LISTS. CONTRACTORS TO H.M. GOVERNMENT DEPARTMENTS AND TO THE PRINCIPAL ELECTRIC LIGHT AND POWER UNDERTAKINGS. WORKS:- COLINDALE WORKS, Telegrams:- WORKS, "EVERGENDOS, HYDE, LONDON." LONDON OFFICES, "EVERECTUS, SOWEST, LONDON." Telephone:- WORKS, 6045 COLINDALE (2 LINES) LONDON OFFICES, 3020 VICTORIA (2 LINES) HENDON, N.W.9. EVERETT, EDGCUMBE & CO LTD ELECTRICAL & MECHANICAL ENGINEERS. 117, VICTORIA STREET, WESTMINSTER, LONDON, S.W.1. MANAGING DIRECTORS: KENELM, EDGCUMBE, M.INST.C.E., M.I.E.E. PATRICK HAMILTON, B. Sc., M.INST. C.E., M.I.E.E. REFERENCES: YOURS EFC/1/AD. OURS D/RB.{R. Bowen}955. 23rd May, 1930. Messrs. Rolls-Royce Ltd., Derby. Gentlemen, We thank you for your letter of the 20th inst., with reference to Warren Motors and note your remarks. With reference to the capabilities of Warren Synchronous Motor with variable frequency and voltage, you are correct in supposing that the variation in both frequency and voltage at the same time extends the range over which the motors will satisfactorily operate. We find, however, that it is incorrect to assume that this is true for any extended range of variation in voltage, although changes in frequency have no effect whatever on the synchronising qualities. As regards voltage the motors may not start when the pressure is less than 80% of the normal, but once they have started the motors will run synchronously with a fall in voltage down to as low as 50%. On a rising voltage, however, the position is not so satisfactory and above 120% of normal there is a tendancy for the speed of the Rotor to drop to half. As it retains its synchronism, at this speed it would seem that increasing the flux in the magnetic circuit results in four magnetic poles being introduced in the Rotor. The conditions under which this change in speed occurs is, however, rather indefinite and the Rotor after dropping into half speed will return to full speed without any apparent reason. This defect could of course be overcome by modifying the design, but at the expense of other features. These is All quotations are estimates only and are subject to the Terms of Business and Conditions of Sale stated in our Current P.T.O. Catalogue. The customer's order shall not be binding on us unless and until such order has been accepted by us in writing. | ||