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The open loop transfer function of a system is
G(s) H(s) = K(1 + s)2 s3
The Nyquist plot for this system is
Correct Option: B
| G(jω) H(jω) = | ||
| (jω)3 |
| |G(jω) H(jω)| = | ||
| ω3 |
∠ G(jω) H(jω) = – 270° + 2tan-1 ω
For ω = 0 , GH(jω) = ∞ ∠– 270°
For ω = 1 , ∠GH(jω) = – 180°
For ω = ∞ , GH(jω) = 0 ∠– 90°
As ω increases from 0 to ∞, phase goes – 270° to – 90° . Due to s3 term there will be 3 infinite semicircle.
