When you turn the throttle in the welding alternating current circuit there is a phase shift between the power supply voltage and current, arcing relatively stable. When welding The dc arc ignition and combustion take place a little better than when welding with alternating current. In the welding circuit also includes a DC choke for improved stability of the arc. However, complete stabilization arcing occurs at the intersection of I-V characteristics of the arc and power source. This point will determine the steady burning of the arc. To improve the excitation of the arc using special high- device – the oscillators, and for a more reliable secondary excitation arc stabilizers are used – special high-voltage pulse generators.
Ignition and sustained combustion of the arc in any way dependent on the current dynamic characteristics of the power source of the arc. The power supply must maintain arcing in the presence of disturbances in the form of voltage changes in the network and provide control of welding process, depending on the condition of the surface work piece and welding wire feed speed. Technical features of the arc at a constant or alternating current can be expressed in that arc, as a flexible gas explorer, can deviate from the normal position under the influence of magnetic fields generated around the arc and the work piece. Magnetic fields affect moving charged particles of the arc column and thus affect the whole arc. This phenomenon is called magnetic blast.
Magnetic fields have a deflecting effect to the arc at irregular and asymmetrical arrangement of the field relative to the arc, especially when welding on DC. The presence of significant near the arc of the ferromagnetic mass also breaks the symmetry of the magnetic field deflects the arc and the arc in the direction of the masses. Magnetic stabilization of the blast affects arc and complicates the process of welding. To reduce the influence of a magnetic blast at the welding arc is necessary to apply special measures. These measures include: a short arc welding, the welding current supply to the point closest to arc, the slope of the electrode in the direction of the magnetic blast, placing in the welding of additional ferromagnetic masses. If you can not get rid of the influence of a magnetic blast that way, it should be replaced power source and weld with alternating current at which the effect of the magnetic blast is much smaller.