| 摘要 |
In a device for control of the speed of a series motor (10) powered from an AC source (16, 17), the free end of the rotor winding (13) is connected to one terminal (16) of the power source and the free end of the stator winding (L1, L2) is connected to the other terminal (17) of the power source via a first two-way silicon controlled rectifier (19), and the stator winding (L1, L2) being further provided with a tap (U) connected to the other terminal (17) of the power source via a second two-way silicon controlled rectifier (20). Means (P1, 22, 23; P2, 24, 25) are provided to generate and supply first trigger pulses to the first controlled rectifier (19) and second trigger pulses to the second controlled rectifier (20), the trigger pulse generating means (P1, 22, 23; P2, 24, 25) being adapted to supply the second trigger pulses only when the first controlled rectifier (19) is fully conducting.
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