1. The effect of an integral controller on the steady-state error ess and that on the relative stability Rs of the system is
- both are reduced
- ess is reduced but Rs in increased
- ess is increased but Rs is reduced
- both are increased
2. The correct sequence of steps needed to improve system stability is
- use negative feedback, reduce gain and insert derivation action
- reduce gain, insert derivation action and use negative feedback
- reduce gain, use negative feedback and insert derivation action
- insert derivation action, use negative feedback and reduce gain
3. In a closed-loop system for which the output is the speed of a motor, the output rate control can be used to
- limit the acceleration of the motor
- limit the speed of the motor
- limit the torque output of the motor
- reduce the damping of the system
4. Consider the following statements in connection with two-position controller:
- If the controller has a 4% neutral zone, its positive error band will be 2% and negative error band will be 8%.
- The neutral zone is also known as dead.
- The controller action of a two-position controller is very similar to that of a pure on-off controller.
- Air-conditioning system works essentially on a two-position control basis.
Which of the above statements are correct?
- i, ii and iii only
- ii, iii and iv only
- ii and iv only
- i, ii, iii and iv
5. Consider the following statements:
A first-order system with a proportional controller exhibits an offset to a step input. In order to reduce the offset, it is necessary to
- increase the gain of proportional controller
- add a derivative mode
- add an integral mode
Select the correct answer using the code given below:
- i and iii only
- ii and iii only
- i and ii only
- i, ii, iii
6. The transfer function of a P-I controller is
- Kp + Kis
- Kp + (Ki/s)
- (Kp/s) + Kis
- Kps + (Ki/s)
7. The characteristics of a mode of the controller are summarized:
- If error is zero, the output from the controller is zero.
- If error is constant in time, the output from the controller is zero.
- For changing error in time, the output from the controller is |K|% for every 1% sec-1 rate of change of error.
- For positive rate of change of error, the output is also positive.
The mode of controller is
- Integral controller
- Derivative controller
- Proportional derivative
- Proportional integral
8. What is the effect on the natural frequency (ωn) and damping factor (δ) in the control systems when derivative controller is used?
- ωn increases and δ decreases
- ωn remains unchanged and δ increases
- ωn remains unchanged and δ decreases
- ωn decreases and δ increases