Abstract: A single-point temperature control system is used with a multi-section furnace to control the exit temperature of a metal workpiece discharged from the furnace. The furnace consists of at least first, second and third sections. The temperature is sensed at the single temperature set point in the second section and compared with a desired set point temperature. The power to the second section is adjusted in order to maintain the desired set point temperature so that the metal workpiece exits the furnace at the required temperature.

Abstract: A furnace for heating ferrous metal workpiece is made up of a plurality of pairs of furnace sections with each pair of furnace section having a longitudinal flux inductors with controls for rapidly adjusting the heating rate according to a desired workpiece discharged temperature from the second of the furnace sections. The second furnace is controlled to maintain a substantially constant workpiece heating temperature. A second pair of furnace sections is provided with a first furnace section utilizing coil pairs with a dual output power supply having independent phase adjustable output currents to vary the current phase relation between the coils between 0 and 180°. The change to the phase relation is used to maintain efficient heating of the metal strip above the Curie temperature.