A unity feedback system has the loop transfer function
where T is a time delay and K is the controller proportional gain. The block diagram is illustrated in Figure P10.35. The nominal value of K =2. Plot the phase margin of the system for 0 ≤ T ≤ 2 s when K = 2. What happens to the phase margin as the time delay increases? What is the maximum time delay allowed before the system becomes unstable?
