What is reverse DC connection? What is positive DC connection?
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DCEN, NCEP – those refer to reverse DC current and positive DC current. MIG welding, shielded metal arc welding, submerged arc welding, TIG welding – which one corresponds to reverse DC current and positive DC current? ? ? ?
When using a DC welder, the power supply output has fixed positive and negative poles. The wiring method in which the welded piece is connected to the positive pole of the power supply and the electrode is connected to the negative pole is called positive connection ； The wiring method in which the welded piece is connected to the negative pole of the power supply and the electrode is connected to the positive pole is called reverse wiring. AC welding power supplies do not have a polarity issue because the positive and negative poles alternate continuously. The shape of the welding arc differs between direct and reverse polarity. Principles for selecting the polarity of the welded joint: 1. When using basic low-hydrogen electrodes in shielded metal arc welding, reverse polarity should always be employed. When direct polarity is used, the arc combustion is unstable; the arc emits a harsh sound, there is significant spattering, and pores are very likely to form. When using acidic electrodes, polarity has little effect on the stable combustion of the arc. By the same logic, when shielded metal arc welding is performed using a direct current power supply, reverse polarity is generally employed as well. 2. When TIG welding steel and brass, direct polarity must always be used. Since the heat generation of the cathode is much lower than that of the anode, when using a direct-current power supply with the positive terminal connected to the anode, the tungsten electrode is connected to the negative terminal; as a result, less heat is generated, overheating is less likely to occur, and the lifespan of the tungsten electrode is longer. A larger welding current can be used with a tungsten electrode of the same diameter. When connected in direct polarity as well, the workpiece acts as the anode, resulting in high heat generation; hence, the penetration depth is large and the productivity is high.
Thank you to the person above; I finally understand what it means when DC is connected in reverse