Importance

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Abstract

A method and apparatus for controlling the temperature of a heater element in accordance with the dwell time of an item to be heated by the heater element. The apparatus of the invention utilizes a temperature tracking circuit which is energized by a low voltage DC power source and a switching system for operating the tracking circuit in either an automatic or standby mode. Sensors are provided for determining the dwell time of an article to be heated by the heater element and a thermocouple or the like is provided for sensing the temperature of the heater element. A heat controller, preferably of the digital programmable variety, is connected to the heater element and is responsive to the dwell time and the thermocouple for controlling the power to the heater in accordance with the dwell time and instantaneous heater temperature whenever the equipment associated with the heater element is operating in the automatic mode. Interposed between the programmable heat controller and the heater element may be a power control device which is responsive to the output of the programmable heat controller for supplying a regulated portion of a high voltage power source to the heater element. In either the automatic or the standby mode, a signal is inputted to the programmable heat controller for maintaining the heater element above a predetermined minimum temperature.

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First Claim