Temp. controller for processing thermoplastic materials - has AC voltage superposed on thermocouple voltage and determines frequency of DC voltage interrogation

摘要

The controller has an electronic comparator with manual setting of the required temp. for at least one heating element, and a thermocouple close to the heating element measuring its actual temp. It is intended for insertion into thermoplastic processing machines and their tools. An AC voltage is superposed on the DC voltage generated in the thermocouple (7) by the heat radiated by the heating element. This modulated voltage is compared in the comparator (8) with a DC voltage corresponding to the required temp. The frequency of the required temp. DC voltage interrogation is determined by the frequency superposed on the actual temp. voltage. It ensures low hysteresis heating energy control for the heating element.