This paper reviews the relative merits of the five main types of power supplies that can be used for electroslag melting. These are: ac single-phase line frequency, ac three-phase line frequency, dc electrode positive, dc electrode negative, and ac low frequency. The comparisons are based mainly on operating experience with furnaces producing industrial-sized ingots [over 12 in. (30.5 cm) in diameter] in a wide variety of ferrous and nickel-based alloys. The power supplies are compared on the basis of the following 14 industrially important indices: power cost per ton, power supply capital cost, electrode costs, total furnace capital cost, melt setup cost, desulphurization in ferrous alloys, molten metal pool depth, absence of inherent stirring, applicability to slab melting, molten slag starting, melt mode flexibility, supply line balance, supply line flicker, and power supply reliability. In general, the survey shows each of the possible melt modes their advantages, disadvantages, and the fact that none of them can be recommended as a universal solution for all applications. It is, however, apparent from the comparisons that ac single-phase line frequency has the broadest potential application.