Abstract
The paper opens with a study of plant controllability, particular attention being paid to the dynamic characteristics of the two most widely used types of electric heater, i.e. induction and resistance. The efficiency of each is considered and comparative figures presented.
Several standard methods of heater control are discussed, together with techniques based upon two- and three-term continuous action controllers, special reference being made to the silicon controlled rectifier (SCR), the advent of which has rendered the continuous control of electric power economically feasible.
Experimental results obtained on an actual extruder using various configurations and types of controller are presented. An analysis of results is given.
Cooling of extruders operating in the “exothermic” mode is discussed. It is hoped to amplify this section with experimental results to be produced before the presentation of the paper.
The paper concludes with a short discussion of the relative merits of the systems considered.
Get full access to this article
View all access options for this article.