A proportional controller with a gain of \( K_c \) is used to control a first order process. The offset will increase, if
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- Derivative control action is introduced
- \( K_c \) is increased
- Integral control action is introduced
- \( K_c \) is reduced
The Correct Option is D
Solution and Explanation
Reducing \( K_c \) reduces controller effort, increasing steady-state error (offset).
Top Questions on Process Control
Consider a process with transfer function: \[ G_p = \frac{2e^{-s}}{(5s + 1)^2} \] A first-order plus dead time (FOPDT) model is to be fitted to the unit step process reaction curve (PRC) by applying the maximum slope method. Let \( \tau_m \) and \( \theta_m \) denote the time constant and dead time, respectively, of the fitted FOPDT model. The value of \( \frac{\tau_m}{\theta_m} \) is __________ (rounded off to 2 decimal places).
Given: For \( G = \frac{1}{(\tau s + 1)^2} \), the unit step output response is: \[ y(t) = 1 - \left(1 + \frac{t}{\tau}\right)e^{-t/\tau} \] The first and second derivatives of \( y(t) \) are: \[ \frac{dy(t)}{dt} = \frac{t}{\tau^2} e^{-t/\tau} \] \[ \frac{d^2y(t)}{dt^2} = \frac{1}{\tau^2} \left(1 - \frac{t}{\tau}\right) e^{-t/\tau} \]- The block diagram of a series cascade control system (with time in minutes) is shown in the figure. For \( \tau_1 = 8 \) min and \( K_s^c = 1 \), the maximum value of \( K_m^c \), below which the cascade control system is stable, is \_\_\_\_ (rounded off to the nearest integer).
\includegraphics[width=0.5\linewidth]{62.png} - Transfer function of transportation lag is
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