Considerations For Cable Tray Grounding Resistance
Cable Tray grounding resistance of note:
1, cable tray grounding circuit disconnected from the protected equipment to ensure accuracy of measurement results.
2, fish and soil to absorb water under too much time, and sharp changes in climate, temperature, pressure, cannot be measured.
3, measured near the ends of no stray currents and very soil.
4, probe needle should stay away from ground water pipes, cables, railway and other large metal body, including current electrode should be kept away from 10m, the voltage should stay away from 50m, such as the metal body and grounding grid when there is no connection, can shorten the distance 1/2~1/3.
5, note the current insert position of the soil, grounding rods should be brought in a State of zero potential.
6, connect the wire well insulated wire should be used to avoid leakage.
7, testing the site not the electrolytic substances and rotting bodies, so as to avoid the illusion.
8, when soil resistivity testing should be chosen, such as winter or dry season in summer time.
9, feel free to check the accuracy of the instrument, (sending unit testing found that once a year)
10, when the galvanometer sensitivity is too high, you can insert a potential probe voltage is lighter in the soil, when the galvanometer sensitivity, and along the probe injection to make it moist.