Wire Butt Welding Device Type BW32 

Ye that's a bubble weld,supposed to be like flower afterwards

very similar to a typical welding process wrt to where the heat comes from. electricity, though it's contact resistance here instead of an arc. www.thefabricator.com/article/tubepipefabrication/comparing-flash-and-butt-welding

High current is flowing through the electrodes which is restricted by resistance of the material which is to be weld. as this resistance that offered in the path of current gernerates heat.

Dear Lala Raheem, here are main electrical specifications: SWITCHBOARDS Voltage 415 [V] ± 10%, 50 [HZ], 3 Phases Installed power: Welding Section 45 [KVA] ED% = 100 Control Section 2 [KW] SERVICE SUPPLY Voltage 230 [V] ± 10%, 50 [HZ], Single phase Kindest Regards MEP SpA