13. Fusion Welding Power Source

In shipbuilding applications, electrical energy is most widely used in the form of arc for several welding processes and as resistance of molten slag in case of electro-slag welding. Arc welding requires a power source that can deliver electrical power at low voltage and high current such that it can establish and sustain an arc plasma column between the welding electrode and the work piece. The welding power sources can have output of alternating current or direct current. These power sources have volt-ampere characteristics typically of constant current or constant potential type. The output may also have a pulsing mode. The classification of the power sources are based on their static volt-ampere characteristics. Constant-potential power sources usually have near constant voltage output compared to constant-current sources having constant-current output. The fast response solid-state sources can provide power in pulses over a broad range of frequencies. These are known as pulsed power sources. The principal metal transfer modes in gas metal arc welding process are short circuiting transfer, globular transfer, spray transfer and Pulsed transfer.