calibration procedure for string potentiometers

UC San Diego 9500 Gilman Drive, MC 0826 La Jolla, CA 92093-0826 ________________________________________________________________________

of 12 1/16/2007 Calibration Procedure For String Potentiometers Document No. SD-400030 Rev 0

CALIBRATION PROCEDURE FOR

STRING POTENTIOMETERS

Document No. SD-400030 Revision 0



REVISION HISTORY

Revision Change Description Approval List

Release Date

0 Original DCR, JJB Jan 16, 2007

Approval List DCR Dan C Radulescu

JJB James J Batti



CALIBRATION PROCEDURE FOR

STRING POTENTIOMETERS

NOTICE: USER IS RESPONSIBLE FOR FOLLOWING THE CORRECT REVISION OF THE DOCUMENT

1. GENERAL DESCRIPTION

The Englekirk Center maintains a number of String Potentiometers with different maximum stroke used to measure displacements in both cases (quasi-static and dynamic). These sensors require periodic calibration to ensure data accuracy.

2. PURPOSE OF PROCEDURE

The purpose of this procedure is to describe the steps required to calibrate the String Potentiometers displacement sensors. It is assumed that the Engineer/Technician has been trained by ESEC site qualified personnel.

3. FREQUENCY

This procedure is to be performed per scheduled calibration period.

4. REFERENCES

Labview based calibration software – Calibrate.vi Trimos V1002+ height stand ESEC Quality Manual Document No: GE-300002 current version ESEC Safety Regulations Instructions Document No: GE-300001 current revision



5. TEST EQUIPMENT NEEDED

1. PXI DAQ System NEES3 2. CALIBRATE.VI software 3. Trimos V1002+ height stand 4. Temperature and humidity sensor

6. PERFORMANCE PRACTICES AND LIMITATIONS

6.1 Collect calibration certificates for the PXI system and for the Trimos height stand. These certificates are to become part of the permanent record for the following calibration.

6.2 Ensure the NI PXI System and Trimos height stand are within

calibration due date.

7. PRE-CALIBRATION PREPARATION

7.1 Ensure all test equipment have been warmed to the manufacturer’s specifications.

7.2 Attach the sensor support plate to the calibration table as shown in

Picture 1

Picture 1



7.3 Insert top connector bolt in upper measuring insert holder. The non-

threaded half goes into the insert holder. See Picture 2

Picture 2

7.4 Turn ON the height stand and move lower connector bolt pass

reference arrows till you hear a “beep”. See Picture 3

Picture 3



7.5 Press button “5” twice. Sine with minimum arrow icon should

appear. See Picture 4

Picture 4

7.6 DAQ Setup. Attach 3 conductors cable to DAQ card. Red and Black

connect to +P and –P respectively. White connects to +S. See Picture 5

Picture 5



7.7 Cable should be exposed at the other end for sensors without 6 pin

connector. The connections in this case are red to green, black to black, and white to white. See Picture 6.

Picture 6

7.8 For sensors with large 6 pin connector, have an extra cable

exposed at one end and small female 6 pin connector at the other end and the small adapter cable as shown in Picture 7

Picture 7



7.9 COMMENTS __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________



8. START CALIBRATION PROCEDURE

8.1. Log into calibration computer and load the VI by selecting “Shortcut to Calibrate.vi”

8.2. On Calibrate.vi select Sensor Type "Displacement”. Fill out Tracking

Number, Model Number, Full Scale Value, Excitation Voltage, Operator Name, Notes, and Standards fields. Under “Procedure no:” enter SD400030. See Picture 8

Picture 8

8.3. Attach sensor to base plate. Tighten down with appropriate bolts. See

Picture 9

Picture 9



8.4. Attach appropriate cable to the sensor. See Picture 10

Picture 10

8.5. Use level to tune plumb from both degrees of freedom. Adjust by moving

height stand and string on insert holder bolt. Always lift height stand to move, never slide it. See Picture 11.

Picture 11



8.6. Extend string and insert holder to highest peg slot possible. See Picture

12

Picture 12

8.7. Press button “6” twice to tare. See Picture 13

Picture 13



8.8. Press RUN arrow on the calibrate software to start the program. Then

press Accept Data Point OK button, then press “Print” yellow button on the height stand. This gives first data point. See Picture 14

Picture 14

8.9. Move stopper to 1/9 of full-scale within peg possibilities to retrieve

another data point. Repeat this moving the stopper to another position to retrieve 10 data points spaced over the range of the sensor.

8.10. Repeat steps 8.3 to 8.9 for other sensors. WARNING: It is the responsibility of the calibration technician to backup all calibration data. Contact the calibration supervisor if there are questions regarding the backup process.

Performed by: Approved by: Print Name and Sign Print Name and Sign __________________ __________________

Date: ________________

calibration procedure for string potentiometers

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