Explanation:

Arc welding is a process of joining metals by melting them with the help of an electric arc. In this process, the basic electrical requirement is that there should be a high open circuit voltage.

High Open Circuit Voltage:

• The open circuit voltage is the voltage present between the welding electrode and the workpiece when the welding machine is switched on but the arc is not struck.

• The high open circuit voltage is required to initiate the arc between the electrode and the workpiece.

• The voltage required to initiate the arc depends on the type of electrode used, the thickness of the workpiece, and the type of welding machine.

• If the open circuit voltage is low, then the arc will not start, and welding will not be possible.

No Arc Blow:

• Arc blow is a phenomenon that occurs during welding when the arc is deflected from its normal path due to magnetic fields present in the workpiece.

• Arc blow can cause defects in the weld, and it can also be dangerous for the welder.

• To prevent arc blow, the welding machine must be grounded properly, and the workpiece should be positioned so that the magnetic fields do not affect the arc.

DC Power Supply:

• In arc welding, a DC power supply is used to provide the necessary voltage and current for welding.

• DC power is preferred over AC power because it provides a stable arc and better control over the welding process.

Coated Electrodes:

• Coated electrodes are used in arc welding to provide a flux that protects the molten metal from atmospheric contamination.

• The coating also helps in stabilizing the arc and improving the quality of the weld.

Conclusion:

Therefore, the basic electrical requirement in arc welding is a high open circuit voltage to initiate the arc, a DC power supply to provide a stable arc, and coated electrodes to protect the molten metal from atmospheric contamination.