Important Short Questions and Answers: Transducers

TRANSDUCERS

1. Define: Transducer

A transducer is defined as a device that receives energy from one system and transmits it to another, often is a different form.

2. Write the parameters of electrical transducer.

The parameters of electrical transducer are:

i. Linearity

ii.Sensitivity

iii.Dynamic range

iv. Repeatability

v.Physical size

3. List the advantages of electrical transducers.

The advantages of electrical transducers are:

i.    Electrical amplification and attenuation can be easily done.

ii.   Mass-interia effects are minimized.

iii.  Effects of friction are minimized.

iv.  Using very small power level.

iv.  Electrical output can be easily used, transmitted and processed for the purpose of measurement.

v.   The output can be indicated and recorded remotely at a distance from the sensing medium.

4.   Define: Viscosity

Viscosity is defined as the property which determine the magnitudes of the resistance of the fluid to a shearing force.

5. Give the types of potentiometer.

The types of potentiometer are:

i.    Translatory

ii.   Rotational

iii.  Helipot

6. Give the limitations of thermistor.

Limitations of thermistor are:

i.    Non-linearity in resistance Vs temperature characteristics.

ii. Unsuitable for wide temperature range.

iii.  Very low excitation current to avoid self-heating.

iv.  Need of shielded power lines, filters etc., due to high resistance.

7.   In what principles,inductive transducer works?

i.    Variation of self-inductance.

ii.   Variation of mutual-inductance.

8.   Write a short notes on LVDT.

LVDT(Linear Variable Differential Transformer) converts the mechanical energy into differential electrical energy. It has single primary winding, and two secondary windings wound on a hollow cylindrical former. An movable soft iron core slides within the hollow former and therefore affects the magnetic coupling between the primary and the two secondaries.

9.   List the advantages of LVDT.

The advantages of LVDT are:

i.    High range of displacement measurement.

ii.   Friction and electrical isolation.

iii.  Immunity from external effects.

iv.  High input and high sensitivity.

v.   Ruggedness

vi.  Low hysteresis and low power consumption.

10. List the limitations of LVDT.

The limitations of LVDT are:

i. Large displacements are required for appreciable differential output.

ii.   They are sensitive to stray magnetic fields.

iii.  Dynamic response is limited.

iv.  Temperature also affects the transducer.

11. List the two physical parameters in strain gauge.

The two physical parameters in strain gauge are:

i.    The change in gauge resistance.

ii.   The change is length.

12. List out the features of piezo-electric accelerometer.

The features of piezo-electric accelerometer are:

 i. Instrument is quite small in size and has a low weight.

ii. The natural frequency is very high.

iii. Useful for high input frequencies and the response is poor at low frequencies.

iv.  The crystal is a source with a high output impedance and in order to avoid loading effect, a voltage monitoring source of a high input impedance should be used.

13. Define: Inductive Transducer

Inductive transducer is defined as a device that converts physical motion into a change in inductance. It may be either of active or passive type.

14. Give the principle of capacitive transducers.

Capacitive transducer principle is a linear change in capacitance with changes in the physical position of the moving element may be used to provide an electrical indication of the elements position.

C=KA/d

Where K= dielectric constant.

A= total area of capacitor surfaces.

d = distance between two capacitive surfaces.

15. What is meant by digital transducers?

Digital transducers are also called as encoders. They are normally in the form of linear or rotary displacement transducers. Hence they require analog to digital converter to realize the digital data.

16. Classify digital transducers.

Digital transducers are classified into,

i. Tachometer transducers ii. Incremental transducers iii. Absolute transducers