Describe the procedure for the measurement of earth resistance by using earth tester.

Describe the procedure for the measurement of earth resistance by using earth tester.
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Measurement of earth resistance by using earth tester: 

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It is connected to earth electrode E, whose resistance is to be measured, and the other spike P and R, as shown in the figure. When handle is rotated the D.C. flows from the generator through the current coil of the movement to the current reverser, and alternating current from the reverser through the soil between the electrode E and R . This voltage drop between electrode P and E is rectified by the rectifier and fed to the potential coil of the meter. As the indication of the meter depends upon the ratio of the potential across its potential coil, and current passing through its current coil, the deflection of the pointer will indicate directly resistance in ohm of the earth electrode under test. 

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