Electronics and Communication Engineering - Automatic Control Systems

11. 

For the system in the given figure, the transfer function C(s)/R(s) is

A. G1 + G2 + G3
B. G1 G2 + G3
C. G1 G2 G3
D. (G1 + G2) G3

Answer: Option B

Explanation:

G1 and G2 are cascaded.


12. 

For the system in the given figure, the characteristic equation is

A. s2 + s(3 + 6a) + 6 = 0
B. s2 + s(3 + 12a) + 12 = 0
C. s2 + 3s = 0
D. s2 + 6s = 0

Answer: Option A

Explanation:

Transfer function to inner loop = .

Then .

The characteristic equation is s2 + 3s + 6as + 6 = 0.


13. 

In control systems the magnitude of error voltage

A. is very small
B. is very large
C. neither small nor large
D. may be any value from 0 to 50 V

Answer: Option A

Explanation:

The error voltage is always very small. A high value of error voltage may cause instability.


14. 

The slope of log-magnitude asymptote changes by - 40 dB/ decade at a frequency ω1. This means that

A. a double pole is present
B. a pair of complex conjugate poles is present
C. either a double pole or a pair of complex conjugate poles is present
D. a pole or zero at origin is present

Answer: Option C

Explanation:

A double pole or pair of complex poles result in - 40 dB/decade slope in log magnitude graph.


15. 

In the given figure the transfer function

A.
B.
C.
D.

Answer: Option D

Explanation:

Use signal flow graph.