slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
LVDT PowerPoint Presentation
Download Presentation
LVDT

Loading in 2 Seconds...

play fullscreen
1 / 19

LVDT - PowerPoint PPT Presentation


  • 1220 Views
  • Uploaded on

LVDT. Linear Variable Differential Transformers. Jason Hart CEE 498. This presentation covers:. How LVDT’s work Types of LVDT’s AC vs. DC LVDT’s Applications to Structural Engineering Costs. How LVDT’s Work. Types of LVDT’s. Unguided Armature Captive Armature

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'LVDT' - bernad


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

LVDT

Linear Variable Differential Transformers

Jason Hart CEE 498

this presentation covers
This presentation covers:
  • How LVDT’s work
  • Types of LVDT’s
  • AC vs. DC LVDT’s
  • Applications to Structural Engineering
  • Costs
types of lvdt s
Types of LVDT’s
  • Unguided Armature
  • Captive Armature
  • Spring-extended Armature
unguided armature
Unguided Armature

Measured Object

Armature must be attached to the specimen

Armature fits loosely in the bore

Body must be separately supported & properly aligned

Elevation/Cross-Section View

unguided armature6
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”).

Measured Motion

Elevation/Cross-Section View

unguided armature7
Unguided Armature
  • Well-suited for short-range, high-speed applications (vibration)

Measured Motion

time

displ.

Elevation/Cross-Section View

captive armature
Captive Armature

Measured Object

Armature must be attached to the specimen

Armature is both guided and restrained by a low friction assembly

Body must be separately supported

captive armature9
Captive Armature

Advantages compared to unguided armature:

  • Better for longer working ranges
  • Preferred when misalignment may occur
spring extended armature
Spring-Extended Armature

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

Elevation/Cross-Section View

spring extended armature11
Spring-Extended Armature
  • The spring-extended armature is best suited for slow-moving applications.
  • Attachment between armature and specimen is not required.
ac lvdt s
AC LVDT’s
  • Smaller size
  • More accurate
  • Can operate within a wide temperature range
  • Lower unit cost.

Advantages compared to DC LVDT’s:

dc lvdt s
DC LVDT’s
  • Ease of installation and signal conditioning. Signal conditioning equipment is part of the LVDT.
  • Can operate from dry cell batteries
  • Usually lower system cost

Advantages compared to AC LVDT’s:

applications to structural engineering
Applications to Structural Engineering
  • LVDT’s are reliable for measuring member deflection in many structural engineering experiments.
  • LVDT’s can measure displacement response directly in dynamic experiments.
  • Mounting the LVDT to a stationary location is critical.
costs unguided armature lvdt
Costs – Unguided Armature LVDT

An LVDT with a 3” range purchased from Macrosensors, Inc. in quantities of one or two:

  • Costs $330 for AC.
  • Costs $485 for DC.
costs spring extended armature lvdt
Costs – Spring Extended Armature LVDT

An LVDT with a +/- 2” range purchased from Macrosensors, Inc. in quantities of one or two:

  • Costs $1156 for AC.
  • Costs $1359 for DC.

In general, costs of LVDT’s range from $50 to $1600, without considering specialty LVDT’s such as hermetically sealed.

summary
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.
references
References

Figure on slide 3 (How LVDT’s work): http://www.daytronic.com/products/trans/lvdt/default.htm

Figure on slide 12 (AC vs. DC):

http://www.macrosensors.com/ms-lvdt_faq-tutorial.html

Cost information obtained from Microsensors, Inc.

Links to LVDT manufacturers found in report by Tjen Nung Tjhin updated on April 24, 2001.