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Transcript of Diff Trafo
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DIFFERENTIALDIFFERENTIAL
TRANSFORMERTRANSFORMER Arizal Arizal DwiantaraDwiantara & Cancer& Cancer DevarthaDevartha
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DEFINITIONDEFINITION
DIFFERENTIAL TRANSFORMER is an ironDIFFERENTIAL TRANSFORMER is an iron--corecoretransformer with movable core. Atransformer with movable core. A
differential transformer produces andifferential transformer produces anelectrical output voltage proportional to theelectrical output voltage proportional to thedisplacement of the core. It is used todisplacement of the core. It is used tomeasure motion and to sensemeasure motion and to sense
displacements.displacements.
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LVDTLVDTLinear Variable DifferentialLinear Variable Differential
TransformersTransformers
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This presentation covers:This presentation covers:
How LVDTs workHow LVDTs work
Types of LVDTsTypes of LVDTs
AC vs. DC LVDTs AC vs. DC LVDTs
Applications to Structural Applications to Structural
EngineeringEngineering
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Types of LVDTsTypes of LVDTs
Unguided ArmatureUnguided Armature
Captive ArmatureCaptive Armature
SpringSpring--extended Armatureextended Armature
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Unguided ArmatureUnguided Armature
Measured Object
Armature fits loosely
in the bore
Armature must beattached to the specimen
Body must be separatelysupported & properly aligned
Elevation/Cross-Section View
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Unguided ArmatureUnguided Armature
There is no wear on the LVDT because noThere is no wear on the LVDT because nocontact is made between armature andcontact is made between armature and
bore.bore.LVDT does not restrict the resolution of LVDT does not restrict the resolution of
measured data (infinite resolution).measured data (infinite resolution).
Elevation/Cross-Section View
Measured Motion
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Unguided ArmatureUnguided Armature
WellWell--suited for short suited for short--range, highrange, high--speedspeedapplications (vibration)applications (vibration)
time
displ.
Elevation/Cross-Section View
Measured Motion
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Captive ArmatureCaptive Armature
Body must be separately supported
Measured Object
Armature must be attached tothe specimen
Armature is both guided andrestrained by a low friction assembly
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Captive ArmatureCaptive Armature
Advantages compared to unguided armature: Advantages compared to unguided armature:
Better for longer working rangesBetter for longer working ranges
Preferred when misalignment may occurPreferred when misalignment may occur
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SpringSpring--Extended ArmatureExtended Armature
Elevation/Cross-Section View
Measured Object
Like the captive armature, it hasa low-friction bearing assembly
Internal spring to continuouslypush the armature to its fullest possible extension
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SpringSpring--Extended ArmatureExtended Armature
The springThe spring--extended armature is best suitedextended armature is best suited
for slowfor slow--moving applications.moving applications.
Attachment between armature and Attachment between armature and
specimen is not required.specimen is not required.
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AC LVDTs AC LVDTs
Smaller sizeSmaller size
More accurateMore accurate
Can operate within a wide temperature rangeCan operate within a wide temperature range
Lower unit cost.Lower unit cost.
Advantages compared to DC LVDTs: Advantages compared to DC LVDTs:
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DC LVDTsDC LVDTs
Ease of installation and signal conditioning. SignalEase of installation and signal conditioning. Signalconditioning equipment is part of the LVDT.conditioning equipment is part of the LVDT.
Can operate from dry cell batteriesCan operate from dry cell batteries
Usually lower system cost Usually lower system cost
Advantages compared to AC LVDTs: Advantages compared to AC LVDTs:
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Applications to Structural Applications to StructuralEngineeringEngineering
LVDTs are reliable for measuring memberLVDTs are reliable for measuring memberdeflection in many structural engineeringdeflection in many structural engineeringexperiments.experiments.
LVDTs can measure displacement responseLVDTs can measure displacement responsedirectly in dynamic experiments.directly in dynamic experiments.
Mounting the LVDT to a stationary locationMounting the LVDT to a stationary locationis critical.is critical.
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RVDTRVDTRotaryRotary Variabel Variabel DifferentialDifferential
TransformerTransformer
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A variation of the LVDT A variation of the LVDT
Intended for angular displacement andIntended for angular displacement androtary position sensing.rotary position sensing.
In all respects it is identical in operation toIn all respects it is identical in operation tothe LVDT device but the rotary motionthe LVDT device but the rotary motionimposes certain restrictions on itsimposes certain restrictions on its
construction.construction.The span is given in angles and can be upThe span is given in angles and can be up
toto ±±3030rr toto ±±4040rr. Beyond that the output is. Beyond that the output isnonlinear.nonlinear.