Linear Variable Differential Transformer 1. What is an LVDT? 2. Circuit Diagram of LVDT 3. Principle of LVDT 4. How LVDT works? 5. Types of LVDT’s 6. Unguided Armature 7. Captive Armature 8. LVDT Characteristics 9. Summary 10. Thank You

1. DEPARTMENT:- IC
SUBJECT:- INDUSTRIAL MEASUREMENT 1
TOPIC:- LVDT
PRESENTED BY:- TANISH GUPTA (150130117029)

2. Linear Variable
differential
Transformer

3. What is an LVDT?
An LVDT is a Linear Position Sensor
with a Proportional Analog Output.
An LVDT has 2 Elements, a Moving
core and a Stationary Coil Assembly.

4. Linear Variable Differential
Transformer
 Transformer: AC Input / AC Output
 Differential: Natural Null Point in
Middle
 Variable: Movable Core, Fixed Coil
 Linear: Measures Linear Position

6. Circuit Diagram of LVDT

7. Principle of LVDT
LVST is the basic transducer which is
always useful in the field if instrumentation.
LVDT works under principle of mutual
induction, and the displacement which is
non-electrical energy is converted into an
electric energy.

9. Types of LVDT’s
Unguided Armature
Captive Armature
Spring-extended Armature

10. Unguided Armature
Measured Object
Armature fits loosely
Armature must be attached
to the specimen
Body must be separately
supported & properly aligned
Elevation/Cross-Section
View

11. Unguided Armature
 There is no wear on the LVDT because no contact is made
between armature and bore.
 LVDT does not restrict the resolution of measured data
(“infinite resolution”).
Elevation/Cross-Section
View
Measured Motion

12. Captive Armature
Body must be separately supported
Measured
Object
Armature must be attached to
the specimen
Armature is both guided and
restrained by a low friction assembly

13. Captive Armature
Advantages compared to unguided armature:
► Better for longer working rangesBetter for longer working ranges
► Preferred when misalignment may occurPreferred when misalignment may occur

14. Spring-Extended Armature
Elevation/Cross-Section
View
Measured Object
Like the captive armature, it has a
low-friction bearing assembly
Internal spring to continuously
push the armature to its fullest
possible extension

15. LVDT Characteristics

16. DC LVDT

17. Summary
 LVDT’s are robust equipment for measuring
deflection.
 AC LVDT’s require separate signal conditioning
equipment, while DC LVDT’s include signal
conditioning equipment on the device.
 There are three types of LVDT: unguided armature,
captive armature, and spring-extended armature.
 AC LVDT’s cost less than DC, but the entire
measurement system must be considered.