| 摘要 |
The invention refers to a sequence control equipment to control the rotative speed of electric direct current motors, which allows the extension to the range of rotative speed control to an electric direct current motor [M], by keeping constant, at the set speed step, the value of the current used for gearing the electric motor [M] supplied through a controllable rectifier [U] from a three phase power network; provided the supply voltage from the power network is variable, the controlling unit uses for the supply to the excitation winding [Ex] of the electric motor [M], a current regulator composed of a magnetic amplifier [AM], with DC output and with one of the control windings connected to a current transducer made from a measurement transformer [TC], connected in series within the supply circuit of the magnetic amplifier [AM], a bridge rectifier [U1] and an adjustable resistor [R1], the second control winding of the magnetic amplifier [AM] being supplied with reference current from a Wheastone bridge comprising three resistors [R2, R3 and R4] and a stabilising bridge diode [V] connected to the power network through an adapter transformer [TA] and a bridge rectifier [U2], the second control winding of the magnetic amplifier [AM] having connected in series some adjustable resistors [R5, R6,...] to set the rotative speed steps to the electric motor [M], by way of a selector switch [S].
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