Electric Furnaces And Their Industrial Applications Scholars Choice Edition PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...enormous currents required necessitate the use of copper leading-in cables at least equal, in cross-sectional area, to the resistance column of metal. Water-cooled iron terminals have been suggested, but fresh difficulties arise out of the magnetization effects; moreover, the use of alternating currents, one of the desirable incidentals to such a large power conversion, leads to fresh complications, owing to skin effect, hysteresis, and consequent loss of power. With a view to surmounting these various difficulties, Kjellin, in 1899, suggested to M. Benedicks, general manager of the works at Gysinge, the form of construction now known as the Kjellin furnace. It consists of an annular groove, or hearth, built of refractory bricks, and closed in at the tap by refractory covers, which are removable for charging purposes. Centrally, within this ring is placed one limb of a rectangular iron core, built up of thin sheet-iron laminations, upon which is wound a copper wire coil, which constitutes the primary winding of a closed-circuit, step-down transformer, the secondary, in the shape of the contents of the annular hearth, having only one turn. Current is supplied to this primary winding at a pressure of 3,000 volts, and the ratio of transformation is such that the current through the furnace charge is approximately equal to the primary current multiplied by the number of turns in the primary winding, or about 30,000 amperes. The first Kjellin furnace was installed at Gysinge in February, 1900, and the first ingot of steel successfully cast on the 18th of the following month, the expenditure of energy being 78 kilowatts for 24 hours, and the yield 270 kgs. An improved efficiency was secured in November, 1900, when a second furnace was...