General Layout of a Feedback Control System

  • Reduce a block diagram of multiple subsystems to a single block representing the transfer function from input to output.

  • Draw the open-loop control system block diagram.

  • Draw the closed-loop control system block diagram.

  • Compare and contrast open and closed loop control.

  • State the principle disadvantage of open-loop control.

  • List the advantages of closed loop control.

General Layout of a Feedback System

where G\(_1\)(s) is a controller or compensator, G\(_2\)(s) represents a plant model, and H(s) represents the measurement dynamics. Y(s) represents the controlled variable, R(s) represents the reference input, and L(s) represents a disturbance.

Solved Examples

Solved Example:

86-1-01

In an open loop control system: (Based on BSNL JE(TTA) Sep 2016-Shift II)

Correct Answer: A

Solved Example:

86-1-02

For open control system which of the following statements is incorrect ?

Correct Answer: B

Solved Example:

86-1-03

A control system in which the control action is somehow dependent on the output is known as: (RSMSSB JE Elec/Mech Dec 2020)

Correct Answer: A

Solved Example:

86-1-04

In open loop system, the control action:

Correct Answer: D

Solved Example:

86-1-05

A good control system has all the following features except:

Correct Answer: B

Solved Example:

86-1-06

A closed loop system is distinguished from open loop system by which of the following? (Vizag MT Elect 2017)

Solution:
A closed loop control system has feedback elements which are absent in open loop control system.

Correct Answer: B