| 摘要 |
1,068,119. Automatic control of current and voltage. TEMESCAL METALLURGICAL CORPORATION. Sept. 21, 1965 [Sept. 28, 1964], No.40156/65. Heading G3R. An electron beam furnace is provided with a regulated power supply which provides a constant voltage over the normal operating current range and which limits the maximum current supplied to the furnace. As shown, the accelerating voltage for a furnace 12 is derived from a D. C. source 16 by way of a series valve 14 and current sensing resistors 62, 64; the heating current for the furnace filament 30 is derived from an A. C. source 130 by way of a diode bridge 134 associated with a thyristor 132, an autotransformer 136 and a filament transformer 36. The accelerating voltage, as detected by a voltage divider 70, 72, 74 is compared in a circuit 20 with a reference voltage derived from a Zener diode 92, and any resulting error signal is applied to control valve 14 so that the accelerating voltage is maintained at a constant value determined by the setting of potentiometer 72. Should the supply current exceed a maximum value because of arcing &c. in the furnace, this maximum value being determined by the setting of rheostat 64, the current signal supersedes the voltage signal and the triode 14 is then controlled so that the current is limited to the desired value. During normal operation the beam current is maintained at a preselected value by a control means 128 which may include a magnetic amplifier and which controls the firing of thyristor 132 in response to an error signal derived from the comparison of the current sensing signal from resistor 62, 64 with a reference signal derived from a potentiometer 126. The circuit 20 includes an OR gate, constituted by transistors 78 and 80, to which the voltage and current signals are applied. |
