Measuring Ground Resistance for Strain Sensors (An Ohmmeter vs. Model 1300)

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Can I use ohmmeter to measure resistance to ground?

When a strain gage sensor is installed on a metal test part, one of the most basic tests for the quality of the installation is the resistance between the gage grid and the part. The insulation resistance can be measured very easily, and with no risk of damage to the gage, using the Micro-Measurements Model 1300 Gage Installation Tester. If the gage is properly installed and tested under laboratory conditions, resistance to ground should be in excess of 20,000 megohms. A resistance of
10, 000 megohms is considered about the minimum for reliably accurate strain measurement. Readings below this value generally indicate some kind of quality defect in the strain gauge installation. Low readings may be caused, for example, by trapped foreign matter, moisture, residual soldering flux, or backing damage from soldering or the use of unqualified corrosive coating. They may also result from moisture migrating to the installation after passing through pinholes in the leadwire insulation. The Model 1300 can be used very effectively to test the integrity of the leadwire insulation, too. For this purpose, the insulated leadwire is placed in a water-filled metal container, and the resistance between the wire conductor(s) and the container measured. The reading should again be at least 20,000 megohms.

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