Electronics and Communication Engineering  Automatic Control Systems  Discussion
Discussion :: Automatic Control Systems  Section 1 (Q.No.1)
1. 
For the system in the given figure the characteristic equation is

[A]. 
 [B]. 
 [C]. 
K(s + 1)(s + 3) = 0  [D]. 
s(s + 2) = 0 
Answer: Option A
Explanation:
Transfer function = .
Hence characteristic equation is .

SHAHWAZ said:
(May 6, 2014)


Where is output and input of this system? 
Ramya said:
(May 29, 2015)


Here characteristics equation is 1+G(s)H(s) = 0. 
SUJJI said:
(Nov 4, 2015)


For unity feedback systems the transfer function is G (S)/1+G (S).
So the characteristic equation is 1+G (S) = 0. 
Navtej Bhangu said:
(May 26, 2016)


Characteristic equation is given by 1 + G(S) H(S) = 0.
So, H(s) = 0. 
Sagar Kumar said:
(Jun 29, 2016)


This is helpful to improve the technical skills. Please provide more advance questions. 
Shristy said:
(May 14, 2017)


I think the H(s) is not 0 it is 1. 
Abhishek said:
(Sep 4, 2017)


I think k(s+1) (s+3) =0 will be the answer. 
Chanchal said:
(Feb 2, 2018)


@ALL.
As per the question, characteristics eq. 1+ G(s).H(s). Here H(s) is unity. So option A is right. 
Mufeed Ardouno said:
(May 1, 2019)


Thank you all. 
Mufeed said:
(May 1, 2019)


For unity feedback systems the transfer function is G (S)/1+G (S).
So, the characteristic equation is 1+G (S) = 0. 
Adam said:
(Aug 21, 2021)


The characteristic equation is nothing more than setting the denominator of the closedloop transfer function to zero (0).
According to this, option D is correct. 
VAIJINATH said:
(Jan 29, 2022)


Anyone, Please explain it fully & clearly. 
RISHI NIGAM said:
(Mar 25, 2022)


Here, we can use 1 + KG(S)H(S) = 0. 