DSC2000 Calibration - Displacement Transducer

Overview

1)   It is recommended that Transducer Calibration is carried out by qualified personnel at a periodic interval defined by the local Standards.

2)   The recommended method for Dual Point Calibration is to use a certified Reference Device that is at least as accurate as the resolution required for the Transducer to be calibrated.

3)   This Support Document covers dual point calibration in CLISP Studio for Displacement transducers connected to a DSC 2000M for dynamic triaxial testing and a DSC 2000MM for Dynamic simple shear or Dynamic triaxials with dynamic cell pressure control.

4)   It is assumed that:

-          CLISP Studio is running

-          The DSC to which the Transducer is connected has been added in CLISP Studio

-          The DSC 2000 is communicating with Clisp Studio

Calibrating a Displacement Transducer

To start the calibration processes open the DSC 2000 Instrument Window in Clisp Studio and select the Analogue Inputs Tab

Figure 1 - DSC Instrument Window in Clisp Studio

Important

When calibrating a displacement transducer it is very important that the correct units are used. The transducer units must be set to mm in Clisp Studio. It is also recommend that the transducer is set to read to 3 decimal places.

To edit the calibration setup it may be required that you press the Edit button and enter the passcode 2603.

Figure 2 - External Displacement Panel

Calibration Initial Setup

Now add the zero and FSD. The Zero is normally 0 and the FSD is the maximum displacement that the transducer can read. This can be found on the Calibration certificate supplied with the transducer.

Figure 3 - Calibration Certificate

Lastly make sure Dual Point is selected. Single factor calibrations cannot be used with the DSC 2000. Once this has been completed press the Write button.

Figure 4 - Writing the FSD

There are two ways the calibration can be completed either by using the calibration certificate or using a reference device. If using a calibration certificate please read section 5 and if you are sing a reference device please read section 6­­­.

Calibration using the Calibration Certificate

In Clisp Studio open the advanced tab, the first number we need to enter is the Raw Divisions at Full Scale

Figure 5 - Raw Divisions at Full Scale

This number can be calculated from a value that is found on the calibration certificate; the number required is the Volts Sensitivity as is highlighted in figure 3.

This number must be put through the following calculation:

So from the example calibration certificate in figure 3 above you would get the following answer:

7.53 / 1000 = 0.00753

So the following would be entered into the raw divisions at full scale. Once this has been entered press the write button.

Figure 6 - Calculated Raw Divisions at Full Scale

To complete the Raw divisions at Zero ensure that the transducer is at is zero position (usually with the spindle fully extended). Then press the Zero button

Figure 7 - Raw Divisions at Zero

Calibration using Reference Device

Set up the Displacement Transducer in the Displacement Calibration Reference Device

Figure 8 – Displacement Calibration Reference Device

With the Displacement Transducer at its zero position in the Reference Device click on the ‘Zero’ button in Clisp Studio, the Display will reset to 0.000.

Figure 9 - Calibration

With the Displacement Transducer at its maximum position in the Reference Device, click on the ‘Gain’ button in Clisp Studio, the Display will reset to the FSD Value. So using the Reference Device you can calibrate your Transducers to a known displacement, ensuring you enter it as your FSD.

Figure 10 - FSD Displacement

If the Displacement Transducer is now moved between the zero and maximum positions, the Display will reflect the displacement accordingly.

Displacement Transducers on Direct Simple Shear Systems

Due to the mechanical design of the Dynamic Simple Shear instruments the displacement transducers must be calibrated in reverse. So that when the transducer spindle is fully compressed Clisp Studio reads this as Zero and when the spindle is fully out, Clisp will read this as the Full Scale Displacement (FSD).

NOTE: Selecting ‘Reverse Travel’ will NOT work, as commands will only be stored in Clisp Studio and not in the DSC