GATE 2021 IN – Question 23
Take clockwise Nyquist encirclements as positive and counterclockwise as negative. The number $N$ of encirclements of $(-1,0)$ for $G(s)=3/(s-1)$ is ______.
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Show answer and explanation
Correct answer: -1 to -1
Explanation
G(s)=3/(s−1) has one open-loop RHP pole, P=1. Unity negative feedback has characteristic 1+G=0, giving s+2=0 and Z=0 RHP closed-loop poles. With clockwise encirclements positive, N=Z−P=**−1**, one counterclockwise encirclement.