| 摘要 |
<p>Current supply source for arc welding, using a main rectifier (a) contg. controllable valves, esp. thyristors (b), plus an auxiliary rectifier (c) employed to facilitate striking of the arc. Rectifier (c) pref. employs semiconductor diodes (d). Both the thyristors (b) and the diodes (d) are connected on the a.c. side to a welding transformer; whereas on the d.c. side, diodes (d) are connected via a capacitor (e) and two longitudinal resistances (f, g) to the arc. The three passive components (e, f, g) also restrict overvoltages, esp. switch overvoltages during idling. Easy striking output (U, V, W) of a welding transformer are connected as shown to both the six thyristors (Th1 to Th6) in the main rectifier, and to six diodes (D1 to D6) in the auxiliary rectifier. A smoothing choke oil (L) is located in the main rectifier circuit, whereas the diodes (D1-6) are connected to a capacitor (C) and to two resistors (R1, R2) facilitating the striking of arc (A). The diodes are directly connected to the thyristors and thus lead overvoltages to capacitor (C). The arc striking current is below the holding current of the thyristors.</p> |
