Patent ID: 6720678
Filing Date: 2004-04-13
Classification: B23K

Abstract:
A control apparatus for controlling supply of voltage from the supply unit to the electrode of a DC electric welder for protecting a user of the electrode against electric shock when changing rods in the electrode, the apparatus comprising:an input terminal for connection to a the supply unit for receiving therefrom a DC current for supply to the electrode; an output terminal for connection to the electrode for supplying the current from the supply unit to the electrode for powering the electrode during use; a supply line connected between the input terminal and the output terminal; an electronic current switch in the supply line operable to transmit or to not transmit the current from the input terminal to the output terminal; a detector circuit arranged to detect the electrical resistance between the output terminal and ground; and a control circuit arranged to actuate the switch to effect transmission of current only if the resistance detected is less than or equal to 120 ohms.