Question

In the fifgure, the Nyquist plot of the open -loop transfer function $G\left(s\right)H\left(s\right)$ of a system is shown. If $G\left(s\right)H\left(s\right)$ has one right-hand pole, the closed loop system is

• A. always stable
• B. unstable with one closed-loop right hand pole
• C. unstable with two closed-loop right hand poles
• D. unstable with three closed-loop right hand poles

Answer 1

The correct option is A always stable

The encirclement of critical point $(-1,0)$ in A.C.W direction is once.
$\therefore N=1,P=1$ (given)
$Z=P-N=O$
No zero in RH of s-plane
So system is stable.