um ▁into ▁the ▁atmosphere . ▁With ▁such ▁equipment ▁very ▁large ▁objects ▁can ▁be ▁w eld ed ▁without ▁huge ▁working ▁ch amb ers . ▁ ▁Work pie ce ▁manip ul ators ▁ ▁Electron - be am ▁w eld ing ▁can ▁never ▁be ▁" hand - man ip ulated ", ▁even ▁if ▁not ▁realized ▁in ▁vac u um , ▁as ▁there ▁is ▁always ▁strong ▁X - rad iation . ▁The ▁relative ▁motion ▁of ▁the ▁beam ▁and ▁the ▁work pie ce ▁is ▁most ▁often ▁achieved ▁by ▁rotation ▁or ▁linear ▁travel ▁of ▁the ▁work pie ce . ▁In ▁some ▁cases ▁the ▁w eld ing ▁is ▁realized ▁by ▁moving ▁the ▁beam ▁with ▁the ▁help ▁of ▁a ▁computer - control led ▁def lection ▁system . ▁Work pie ce ▁manip ul ators ▁are ▁mostly ▁designed ▁individually ▁to ▁meet ▁the ▁specific ▁requirements ▁of ▁the ▁w eld ing ▁equipment . ▁ ▁Power ▁supply ▁and ▁control ▁and ▁monitoring ▁electron ics ▁ ▁Electron - be am ▁equipment ▁must ▁be ▁provided ▁with ▁an ▁appropriate ▁power ▁supply ▁for ▁the ▁beam ▁generator . ▁The ▁acceler ating ▁voltage ▁may ▁be ▁chosen ▁between ▁ 3 0 ▁and ▁ 2 0 0   k V . ▁Usually ▁it ▁is ▁about ▁ 6 0 ▁or ▁ 1 5 0   k V , ▁depending ▁on ▁various ▁conditions . ▁With ▁rising ▁voltage ▁the ▁technical ▁problems ▁and ▁the ▁price ▁of ▁the ▁equipment ▁rapidly ▁increase , ▁hence , ▁whenever ▁it ▁is ▁possible ▁a ▁lower ▁voltage ▁of ▁about ▁ 6 0   k V ▁is ▁to ▁be ▁chosen . ▁The ▁maximum ▁power ▁of ▁the ▁high