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Measurement method of ground resistance tester

time:2020/6/20   source:华天电力  reading:318 time

There are many factors that can influence of grounding resistance: grounding pole size, length, thickness, shape, number, buried depth, the surrounding geographical environment (such as ground, ditches, slopes), soil moisture, texture, etc., in order to keep the equipment in good grounding, grounding resistance measurement can be made by using grounding resistance tester, grounding resistance measurement method have?


The measurement methods of ground resistance can be divided into voltage ammeter method, ratio meter method and bridge method. According to the specific measuring instruments and the number of rods, it can be divided into hand type ground resistance meter method, clamp type ground resistance meter method, voltage ammeter method, three-pole method and four-pole method.


Earth Resistance Tester.png


When measuring the ground resistance, some factors may cause the ground resistance to be inaccurate:


(1) The soil composition around the ground network is inconsistent, the geology is different, the density and moisture is different, the ground stray current, especially the overhead ground wire, underground water pipe, cable skin, etc., has a great impact on the test, the solution: take different points for measurement, take the average value.


(2) The direction of the test line is wrong or the distance of the test line is not long enough. Solution: find out the test direction and distance.


(3) Excessive resistance of auxiliary grounding pole; Solution: Water the pile or use a drag reducer to reduce the pole grounding resistance.


(4) The contact resistance between the test fixture and the ground measuring point is too large; Solution: Abrasive the contact with a file or sandpaper, and clamp the polished contact fully with a test clamp.


(5) Interference effect. Solution: Adjust the direction of the line, avoid direction interference as far as possible, so as to reduce the beat of meter reading.


(6) Instrument use problem, battery power is low. Solution: Replace the battery.


(7) The value of the grounding resistance tester drops; Solution: Recalibrate to zero.


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