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Electronics and Communication Engineering - Automatic Control Systems

Exercise : Automatic Control Systems - Section 3
6.
Which of the following rotors are used in two phase ac servomotor?
  1. Solid iron rotor
  2. Squirrel cage rotor
  3. Drag cup rotor
Of the above the correct ones are
1, 2, 3
1, 2
2, 3
1, 3
Answer: Option
Explanation:

Solid iron rotor would give rise to eddy currents.

7.
For the system of given figure the closed loop transfer function

Answer: Option
Explanation:

or .

8.
Given figure shows a unity feedback system. The ratio of time constants for open loop and closed loop response are
1 : 1
2 : 1
3 : 2
2 : 3
Answer: Option
Explanation:

For open loop time constant = 0.25

For closed loop and time constant =

Hence ratio of time constants is 3 : 2.

9.
For a second order system damping factor is 0.1. If ωd is frequency of damped oscillations and ωn is natural frequency, then
ωd ≈ ωn
ωn ≈ ωn
ωd ≈ (ωn)2
Answer: Option
Explanation:

ωd = ωn(1 - 0.1)2 ⋍ ωn

10.
For the block diagram of in the given figure, the transfer function C(s)/R(s) is
Answer: Option
Explanation:

Forward transfer function is G + H1.

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