Displacement transducers

[tolikon]

I used PSI TRONIX five inch displacement transducers to find out displacement on a beam. I have the output in volts, how can I convert into inches. what kind of calibration information is needed from the transducer and how to use that to get my result in inches.

[EricS.]

The manufacturer should provide you with an equation, or at least a conversion constant in the form of:  Inches of Displacement = Volts Out * X  where X will be in the units "inches/volt"

Then in software all you have to do is take your raw voltage and multiply it by the X value from the manufacturer and you will have the output displacement.

[tolikon]

From the manufacturer, I have position value of 195 MV/V/Inch. How do I corelate this value, if my excitation is 10V or 5V.

From the dasylab, an avergae of 2.5 V showed up in my recorder.

[TomRizzo]

The information you recieved from the manufacturer is only good for the amplifier.  How is the LVDT connected to DASYLab?

Do you have an aplifier before your DAQ card?

In any case, the best way to calibrate is to use a refence gauge and compare output to it.  in DASYLab you would use the linear scaling module to set the moltiplication factor to give you the proper dimensioning.

[EricS. · Accepted solution]

Yes, you can definitely create your own linear interpolation of raw data compared to a reference gauge.  That would produce an experimental correlation from volts to inches, which would definitely work.  

You can also use the data the manufacturer gave you: 195mV/V/In

So, assuming you have 10Vex, this would be 1.95V/In

You are reading 2.5V, so 2.5V/(1.95V/in) = 1.28 Inches

So, when you read 2.5 Volts, it should correspond to a displacement of 1.28 inches.

You could also do the same calculation another way:

You're reading 2.5V, divide by 10Vex = 250mV/V  output

You know the rating of 195mV/V/Inch,  so 250mV/V divided by 195mV/V/Inch = 1.28 inches.

[MHa]

LVDT - you needs similar informations, for instance here from germany enterprise Micro-Epsilon:

http://www.micro-epsilon.co.uk/_sitetools/suche/
searcg for LVDT, here for instance

http://www.micro-epsilon.co.uk/download/products/dax--induSENSOR-LVDT-Sensor--en.html

Model KRS719(01)

Article 4350026.01

Measuring principle LVDT (page 12)

Measuring range ± 1 mm

plunger 0800080 (ø2 x 62 long)

with thread M4x0.5 (15 mm long)

Linearity ±0.15 % FSO (3 μm)

Resolution 0.07% FSO (1.4 μm)

Frequency response 100 Hz (-3dB)

Housing nickel-plated steel

Temperature stability zero ± 50 ppm / °C

Output 4 ... 20 mA

options: 2 ... 20 mA / ± 3.9 VDC

Power supply 22.8 ... 25.2 VDC

sensor -20°C ... +80°C

electronics 0° C ... +50°C

Adjustment zero, gain

Protection class IP 67

Electronics incl. circuit board BSC719(02)-I, article 2208078.02

Best regards,

MHa