Inductive transducers can be either self-generating or passive types that use principles of self-inductance, mutual inductance change, or eddy current production to measure displacement, position, motion, or presence of metals. They have advantages of high responsivity and insensitivity to load effects but disadvantages of reduced operating range due to side effects and sensitivity to temperature and magnetic fields. Common applications include detection of metals, touch pads, position and motion measurement.

1. Inductive transducer
Inductive Transducers may be either
▫ Self - generating type transducers
▫ Passive type transducers
Principle :
 Self inductance,
 Mutual inductance change ,
 Eddy current production

2. Self inductance
Inductance = 𝑁2𝛍 𝐺
G= geometric form factor , G=A/I
A-------cross sectional area
l--------coil length
𝛍--------Permeability

3. Mutual inductance change
M= 𝐿1. 𝐿2
 Inductance is altered by coupling coefficient
Mutual inductance change is adjusted by measurement and displacement
Eddy current production
 Change in distance of coil or plate –measures displacement

4. Types
1) Simple inductance type

5. 2)Two type mutual inductance

6. Advantages
 Responsivity is high
Load effects will be reduced
Strong against ecological quantities
Disadvantages
Operating range reduced by side
effects
Working temp should be under curie
temp
Sensitive to magnetic field

7. Applications
Detection of metals
Touch pad
Measure position
Dynamic motion
Missing parts
Counting the no: of objects

8. Linear Variable Differential Transformer
(LVDT)

9. Linear Variable Differential Transformer
(LVDT)

10. when the core is in the center
so that V1=V2, there is no
voltage output, Vo = 0
V1 > V2 ,Vo increase
V2 > V1 ,Vo decrease

11. Advantages
High sensitivity
Excellent repeatability
Simple, Easy to maintain
Low cost
Disadvantages
Sensitive to stray magnetic field
Temperature affects the performance
Inherently low in power output

12. Applications
Power turbines
Hydraulics
Automation
Aircraft
Satellites
Nuclear reactors

13. Inductive potentiometer
 Used to measure angular displacement
Stator -rotor
Synchro-resolver type

14. Electromagnetic sensor
 A moving magnetic field causes an current to flow
through conductive material.
Sensor measures the induced electrical currents
Eg . Hall sensor

15. Hall sensor
Activated by external magnetic field
O/P signal function of magnetic field density
Hall voltage VH
Hall voltage α strength of magnetic field