Controller Components – Part 1 Objective Questions
1. Low power transducers called sensors prefer:
a) Linear relationship between controlled variable and output variable
b) Non-functional relationship between controlled variable and output variable
c) Non-linear relationship between controlled variable and output variable
d) Not related with each other
Answer: a
Explanation: Sensors are different from transducers as in transducers the energy is converted from one form to another while in sensors only the energy is sensed not converted and it is possible to get the accurate results in less time.
2. The chief advantage offered by the electronics is:
a) Differencing and stable amplification by Op-Amp
b) Stable amplification of power level by use of power transistor and SCR’s
c) Differencing and stable amplification of power level by Op-Amp
d) No amplification with the Op-Amp
Answer: c
Explanation: Advantage of electronics is that every type of energy is converted into measurable and storage energy and electronically differencing to get the error signal and its amplifier.
3. Which of the motions in actuators are preferred:
a) Translator
b) Rotary
c) Stationary
d) Non-Stationary
Answer: b
Explanation: An actuator in a control systems perform variety of task in hydraulic, pneumatic and electrical system but majorly they are all controlling rotary motions.
4. Assertion (A): Electric actuators are used control system for high torque applications.
Reason (R): Due to linear speed-Torque characteristics.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: a
Explanation: Electric actuators are the devices that are used to convert non measurable form of energy into measurable and are used in high torque applications due to linear speed torque characteristics but not used in low speed where hydraulic actuators are still used.
5. Low power DC and AC motors are also known as _________
a) Servomotors
b) Tachogenerators
c) A.C. generators
d) D.C. generators
Answer: a
Explanation: Electric actuators are of two kinds’ ac and dc motors and with low power rating they are called ac servomotors.
6. The torque developed by the motor when stationary with the full applied voltage__________
a) Stalled torque
b) Torque
c) Force
d) Couple
Answer: a
Explanation: Stalled torque is the important figure of merit of Servomotor which is important for linearity characteristics.
7. High torque/inertia ratio means:
a) Stalled torque
b) Stalled inertia
c) Stalled toque/inertia ratio
d) Lower motor time constant
Answer: d
Explanation: High torque/inertia ratio means the ration of torque to the inertia should be high as for higher torque the inertia must be very low and this indicates lower time constant as it leads to dynamic response.
8. Electric actuators for stepped motion are known as stepper motor.
a) True
b) False
Answer: a
Explanation: Stepper motors are the motors in which the motion generated is in the form of steps with respect to the time and works on the same principle as electric actuators but with stepped motion.
9. DC motors can be modeled as:
a) Armature controlled
b) Field Controlled
c) Both a and b
d) None of the mentioned
Answer: c
Explanation: DC motors are the motors that work o the direct current and commutators are replaced by slip rings and can be classified based on the construction as armature controlled or field controlled.
10. Assertion (A): Pneumatic actuators are not as messy as hydraulic ones.
Reason (R): Pneumatic suffer from leakages and inherent inaccuracies.
a) Both A and R are true and R is correct explanation of A
b) Both A and R are true but R is not correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: b
Explanation: Pneumatic actuators are the devices that convert the motion of air into measurable form of the energy and can also be used in low speed applications but they suffer leakages and inherent in accuracies.
11. DC motors are constructed using:
a) Permanent Magnet
b) Electromagnet.
c) Magnets are not used
d) Plastics
Answer: a
Explanation: DC motors are are the motors that work o the direct current and commutators are replaced by slip rings and now constructed using permanent magnets having high flux density.
12. Permanent magnets used for DC motors because of:
a) High residual flux density
b) High coercivity
c) Both a and b
d) Retentivity
Answer: c
Explanation: Permanent magnets are hard magnets with the area og B-H curve more and they are less used at core of the magnet and are used for DC servomotors as they have high residual flux density and high coercivity.