| 摘要 |
768,390. Control of D.C. motors. WOODS OF COLCHESTER, Ltd. Nov. 7, 1955 [Dec. 14, 1954], No. 36216/54. Class 38(3) A pair of contra-rotating axial flow fans are driven by similar compound-wound D.C. motors, maximum speed and power being obtained by connecting the two motors in parallel across a source of supply. For operation at reduced speed and power, the armatures and series field windings are connected in series with one another across the supply, and the shunt field windings are connectable in the different manners, namely, open circuit, series, and parallel, to obtain successively diminishing speed and power outputs. Control of the motors may be effected by means of a multi-position controller which is interlocked with a starter switch so that the starter contacts are opened before the controller is moved from one operative position to another. |
