The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is________________?

Question

Accepted Answer

5π/12. The formula relating phase lag ($	heta$), time constant ($	au$), frequency ($\omega$), and dead time ($L$) is $	heta = -\omega L / \sqrt{1 + (\omega 	au)^2}$. Solving for $L$ gives the result matching option A.