| 摘要 |
PURPOSE:To miniaturize the device by providing a setting circuit that sets an increase of short circuit current controlled by a controlling circuit for the short circuit current to an arbitrary time constant, and thereby controlling short circuit current using a simple electronic circuit. CONSTITUTION:When short circuit is detected and an analog switch S1 turns off and terminals A, C of an analog switch S2 becomes short-circuited state, a capacitor C1 is charged from voltage at the time of detection of short circuit by resistance RVR of a variable resistance VR2 and increases at a time constant C1RVR. Voltage of the capacitor C1 at this time is inputted as a set value to a comparator 6 through an amplifier 5 consisting of an operational amplifier and the analog switch S2, and determines current value that makes a transistor Tr1 off, and accordingly, arc current that flows in the transistor Tr1 increases at a time constant C1RVR. Accordingly, by setting the value of C1RVR properly, a welding machine of small spatter can be obtained. |
