What is the difference between a primary and a secondary control element?
A. Primary control elements manipulate process variables directly, while secondary control elements manipulate primary control elements
B. Primary control elements are used for open-loop control, while secondary control elements are used for closed-loop control
C. Primary control elements use feedback, while secondary control elements do not
D. There is no difference between a primary and a secondary control element
Answer:A
What is the difference between a primary and a secondary control element?
A. Primary control elements manipulate process variables directly, while secondary control elements manipulate primary control elements B. Primary control elements are used for open-loop control, while secondary control elements are used for closed-loop control C. Primary control elements use feedback, while secondary control elements do not D. There is no difference between a primary and a secondary control element