Question

A system for which the steady state error is zero for a unit-step is of type (A) Zero (B) 1 (C)2 (D) 1 or 2 (E) none of above

Answer 1

Answer:

(E) 1 or  2

Explanation:

Steady state error for unit step input is given by $e_{ss}=\frac{1}{1+k_p}$ where $K_P$ is position error coefficient the value of  $K_P$ is given by $k_p=\lim_{s\rightarrow 0}G(s)$ it will be only finite when the type of the open loop system will be 0 when the of the system will be 1 or 2 then $k_p$ becomes infinite and steady state error will become zero so the option (E) will be the correct answer