Aftercooling,theweldingobjectisgluedtogether.Atthispoint,duetotheminimumgapbetweentheelectrodeandtheweldingpieceatthemomentoflifting,thevoltagebetweentheelectrodeandtheweldingpieceishigher(60--70v),andthepreheatingmakesiteasytoemitelectr***attheendoftheelectrodeandwheretheweldingpieceiswelded.Asaresult,theairinthegapisbrokendownandconductive,andadazzlingsparkisproduced,whichiscalledarcdischarge.Thetemperatureofarcdischargecanreachmorethan2000k,theelectrodeandweldingpiecearemelted,thustheweldingisrealized.Afterarcdischargestarts,thevoltageofelectrodeendandweldingpiece(arcvoltage)isreducedbyabout30vs.theloadformedbyarcisresistiveload.)