| 摘要 |
539,734. Motor control systems. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 2, 1940, No. 13750. Convention date, Sept. 1, 1939. [Class 38 (iii)] To avoid excessive wheel slippage in a traction system comprising series-connected motors 10, 11, 12, 13, pairs of which are on different axles, an impedance comprising elements 30, 31, 32 normally short-circuited by switches 33, 34, 35 is connected in series with the motors, and a relay 36 responsive to difference in speed between the pairs of motors is arranged to cause opening of the switches to insert impedance in circuit. The relay 36 comprises a restrained shaded pole induction motor and its operating winding is connected between the mid-point on a reactor 40 and a point normally at the same potential, i.e. the point of interconnection of the two pairs of motors. The impedance includes resistive and inductive portions in order that current limitation may be effected at low motor speeds when power factor is low and also at high speeds and correspondingly high power factor. Closure of the switches 33, 34. 35 in sequence is provided for by copper jackets of different dimensions on two of the magnet cores. |
