SMALL-SIZE ELECTRIC WELDING APPARATUS Russian patent published in 1998 - IPC

FIELD: electrical engineering, possibly manual arc welding apparatuses and power sources for supplying controlled direct current to storage cells, heaters, illuminators. SUBSTANCE: small-size electric welding apparatus includes transformer, whose primary winding is connected with current limiting resistor. Loading circuit of secondary winding of said transformer is connected with relay whose contacts in dependance upon loading current control switching of said resistor. Apparatus also includes rectifier. Novelty is unit for protecting apparatus against short circuiting. Said unit is threshold unit with two inputs including different-polarity transistors whose bases through Zener diodes, time setting C-circuits of members for delaying operation of said protection unit and diodes are connected with respective outlet terminals of apparatus. Emitters of said transistors are connected with parametric voltage stabilizers, their collectors being loads for relay winding whose closing contacts are connected with circuit for controlling symistor connected in parallel with said current limiting resistor of primary winding of transformer. EFFECT: higher efficiency. 1 cl, 1 dwg