| 摘要 |
1,136,253. Magnetic amplifiers. LANSING BAGNALL Ltd. 12 July, 1966 [14 July, 1965], No. 29898/65. Heading H3B, [Also in Divisions G3, H1 and H2] A transductor, for applying a variable proportion of the pulses from a multi-vibrator and shaping circuit to the firing circuit of a thyristor in circuit with an electric motor, comprises cores 12, 13 separated by air gaps 16, 17 wich a reactance winding 18 around the core 12. Around the core 13 there is a single-turn winding 19 carrying the motor current. In the main air gap 14 there is a movable permanent magnet 22 coupled to a control pedal for the motor. Initially the transductor is fully saturated by the control magnet, thus inhibiting pulses to the thyristor, until displacement of the magnet from the position between poles 15 reduces the saturation and increases the pulse repetition rate. The transductor also tends to be saturated by the winding 19, to prevent the supply of "on" pulses until the motor current decreases to a safe value. The winding 18 is connected across the base and emitter of a transistor and is energized by pulses from the shaping circuit, the arrangement being such that the transistor is cut-off to prevent the application of firing pulses to the thyristor when the impedance of the winding 18 is low due to saturation. |
