Project ForgeInstrumentation & Process Control
Controller Modes
GATE 2009
Medium
A block diagram has R(s)→[sum +/−]→Kc=2→U(s)→Gp=2/[(2s+1)(3s+1)]→Y(s), with unity feedback. For a unit step change in the set point, R(s), the steady state offset in the output Y(s) is
- 0.2
- B0.3
- C0.4
- D0.5
Explanation
At s=0: Gp(0)=2/(1×1)=2. Loop gain KcGp(0)=4. Y(0)/R(0)=4/(1+4)=0.8. Offset=R−Y=1−0.8=0.2.
Source: GATE CH 2009 (2009)
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