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How to use ground resistance measuring instrument

time:2020/9/8   source:华天电力  reading:230 time

How to use ground resistance measuring instrument


Preparation before use


1) Familiarize with the instruction manual of the ground resistance measuring instrument, and fully understand the structure, performance and use method of the instrument.


2) Prepare the necessary tools and all instrument accessories for measurement, and wipe the instrument and the grounding probe clean, especially the grounding probe, be sure to clean up the dirt and rust stains on the surface that affect the conductivity.


3) Disconnect the connection point of the grounding trunk line and the grounding body or the connection point of all grounding branch lines of the grounding trunk line, so that the grounding body will be separated from any connection relationship and become an independent body


Earth Resistance Tester.png


Measurement procedure


1) Insert the two grounding probes into the ground 20m and 40m away from the grounding body along the radiation direction of the grounding body, and the depth of insertion is 400mm,


2) Place the grounding resistance measuring instrument flat near the grounding body and connect the wires. The wiring method is as follows:


①Use the shortest dedicated wire to connect the grounding body to the terminal "E1" (three-terminal button measuring instrument) of the grounding measuring instrument or the common terminal (four-terminal button measuring instrument) shorted to C2.


②Connect the measuring probe (current probe) 40m away from the grounding body with the connection button "C1" of the measuring instrument with the longest dedicated wire.


③Connect the measuring probe (potential probe) ⒛m away from the grounding body to the terminal "P1" of the measuring instrument with the remaining special wire in the middle length.


3) After placing the grounding resistance measuring instrument horizontally, check whether the pointer of the galvanometer points to the center line, otherwise adjust the "zero adjuster" so that the pointer of the measuring instrument points to the center line.


4) Set the "magnification scale" (or coarse adjustment knob) to the maximum multiple, and slowly rotate the generator handle (the pointer starts to shift), and at the same time rotate the "measurement dial" (or fine adjustment Knob) to make the pointer of the galvanometer point to the center line.


5) When the pointer of the galvanometer is close to balance (the pointer is close to the center line), shake the handle to speed up to 120r/min or more, and adjust the "measurement dial" to make the pointer point to the center line.


6) If the reading of the "measuring dial" is too small (less than 1) and it is not easy to read and accurate, it means that the magnification scale is too large. At this time, you should set the "magnification scale" to a smaller multiple, readjust the "measurement dial" so that the pointer points to the center line and read an accurate reading.


7) Calculate the measurement result, that is, R ground = "magnification scale" reading × "measurement dial" reading.


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