Search results
Results from the WOW.Com Content Network
Electrical resistance survey. Electrical resistance surveys (also called earth resistance or resistivity survey) are one of a number of methods used in archaeological geophysics, as well as in engineering geological investigations. In this type of survey electrical resistance meters are used to detect and map subsurface archaeological features ...
A grounding resistance tester also called an earth tester is a soil resistance measuring instrument. It is used for sizing and projecting grounding grids. [1] The first soil resistance measuring instrument was invented in the 1950s by Evershed & Vignoles Meggers who made the first insulation and earth resistance testers. [2]
2D resistivity inversion of ERT data Deployment of a permanent electrical resistivity tomography profile on a longitudinal section of an active landslide.. Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more ...
The resistance of a geological material depends on several components: the presence of metal ores, the temperature of the geological layer, the presence of archeological or structural features, the presence of dissolved salts, and contaminants, porosity and permeability. There are several basic methods for measuring soil resistance.
In some telegraph and power transmission circuits, the ground itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor (see single-wire earth return and earth-return telegraph). For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other ...
Four-point measurement of resistance between voltage sense connections 2 and 3. Current is supplied via force connections 1 and 4. In electrical engineering, four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements ...
This part of IEC 61557 specifies requirements for insulation monitoring devices (IMD), which permanently monitor the insulation resistance R F to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as of unearthed d.c. IT systems with voltages up to 1 500 V d.c. independent from the method of ...
Magnetotellurics (MT) is an electromagnetic geophysical method for inferring the earth 's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ranges from 100 m below ground by recording higher frequencies down to 200 km or deeper with long-period ...