Matsushita Electric Industrial Co., Ltd.

Kazuo Kimoto

Seigo Hagiwara

Yoshiaki Tanaka

Naoki Kawai

Norikazu Osaki

An arc welding and arc plasma cutting machine having a dc high-voltage generator is provided. The dc high-voltage generator includes a first dc power source, a second dc power source, an one-way rectifier, and a voltage clamping circuit. The first dc power source applies a dc voltage through the one-way rectifier across an electrode and a work piece. The second dc power source is connected across the first dc power source and superimposes a dc voltage on the power produced by the first dc power source for developing an arc discharge across the electrode and the work piece. The voltage clamping circuit connected in parallel to the one-way rectifier to restrict a high-voltage applied to the one-way rectifier below a given level for protecting the one-way rectifier from breakage due to application of the high-voltage.

Arc welding and arc plasma cutting machines having improved DC

In an arc welding machine and a plasma cutting machine, by connecting the output of a second DC power supply unit to a circuit fed by a first power supply unit, a DC high voltage from the second DC power supply unit is applied, during start, across an electrode and a base metal which are not in contact with each other, so that radiation noise can be reduced considerably and leakage of high frequency power from an extension cable can be eliminated to attain steady arc start.

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Habikino, Japan

Kazuo Kimoto