| 摘要 |
<p>Arc welding appts. uses current from an AC or three-phase mains supply. Between the mains switch and the welding electrodes there is (a) a rectifier with voltage adjustment; (b) a medium frequency (m.f.) inverter; and (c) a second rectifier. Pref. (b) consists of an m.f. transformer and an inverter circuit contg. simple controlled rectifier valves, a capacitor, and a commutation choke. The slopes of the static characteristic curves for the welding current are pref. altered by (1) dimensioning the choke; or (2) distribution of the winding on the legs of the iron core in the m.f. transformer. Wt. of conventional appts. providing 300 amps. for 60% operating time is >=200 kg. This is reduced by 75%. Components required for smoothing the d. c. can be reduced to a min. or be eliminated, as the output of the inverter (b) is not sinusoidal but rectangular.</p> |
