Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( - 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as________________?
Correct answer: B. 12, 0.6, 0.12
- A. 8, 0.6, 0.08
- B. 12, 0.6, 0.12
- C. 8, 0.6, 0.12
- D. 12, 0.4, 0.08
Explanation
For the conservative largest-error case, each uncertain process parameter is taken at its upper 20% limit: gain 10(1.2) = 12, time constant 0.5(1.2) = 0.6, and dead time 0.1(1.2) = 0.12. These values correspond to option b.
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