DE2348770

The furnace heating winding is divided in several sections, each with its own temperature sensor and a controller. Nominal values for the controllers are set by a compensation circuit, with nominal values for the hotest and coldest heating zone set during responding display systems during the continuous heating phase of a temperature cycle. Nominal values for intermediate zones are automatically set by voltage dividers. The display system has calibrated potentiometers, digital resistor switch combinations and/or measuring instruments in parallel with the potentiometers. The furnace is also controlled during heating up and cooling down phases by connection of a variable voltage source in opposition to the compensation voltages. Time control is provided for the continuous operation period.