Dear sirs,

About DT85G LVDT I have these questions:

1. What kind(type) of LVDT, supports with DT85G?
2. How can we connect LVDT to the system?
3. How can system excite the LVDT?
4. What is the range of LVDT input of the DT85G?

Thanks for your attention to this matter
m.v.tehrani

Good morning M.V. Tehrani,

1. Types of LVDT's
   The DT80 Range loggers, of which the DT85g is one of the family, can support any LVDT with a DC Voltage output.

2. Connecting LVDT's
   Connect the signal +/- to either the +/- or */# terminals on the DT80
   For more details please refer to the DT80 manual in the section on Voltage measurements.

   If the output of the LVDT is over 3 VDC (Most are +/- 10 VDC) then you will have to select the High Voltage (HV) channel type. In DeLogger under "Signal" select Voltage, "Type" select HV (High Voltage), In "Wiring" select the configuration that matches the wiring you used to connect the LVDT and also select the channel number.

3. LVDT Excitation.
   You will need to provide an external power supply for you LVDT's

4. Range of LVDT.
   The range doesn't matter to the dataTaker, It simple measures a Voltage which you can then scale to engineering units.

For example if you have an LVTD that has a range of +/- 100 mm and an output of +/- 10 VDC then;

In DeLogger to define a span click on the "Scaling" tab, In the Type column select "Span" In "Physical 1" enter -100, in "Physical 2" enter 100, In "Signal 1" enter -10, in "Signal 2" enter 10 and in the "Text (units)" enter mm

Then go to the schedule you are using to read the LVDT output. In "Signal" select Voltage, In "Type" select HV, in "Wiring" Select the wiring connection and channel number you are using.

To apply the span go to the "Scaling" column and click in the cell on the row you are using and Select the span you have just defined e.g S1.

Cheers,
Roger

Hello,

Ah... here are the zeros Roger lost in that other thread ...

In DeLogger to define a span click on the "Scaling" tab, In the Type column select "Span" In "Physical 1" enter -100, in "Physical 2" enter 100, In "Signal 1" enter -10, in "Signal 2" enter 100 and in the "Text (units)" enter mm

Since the example was a +/- 10 VDC output, Signal 1 and 2 should read -10 and 10 accordingly I assume ...

Cheers
B.

Hi all,

Most LVDT's are +/- 10 VDC full scale, but I have seen others 0 to 5 VDC, 0 to 3 VDC etc. It all depends on how the sensor was designed. Now when you come to actually using the LVDT the zero point in the set up might not be the zero point of the LVDT.

For example if you are breaking a beam in bending so all the deflection is in one direction. When placing the LVDT you move the LVDT up against the under side of the beam until you have a zero Volt reading then move it up a measured amount and call that point Zero. You can the adjust the scaling to reflect the new zero point.

Cheers,
Roger

Dear Roger,

Thanks a lot for your information.

Best regards,
M.V.tehrani