8
5.
E
interface:Earth electrode
6.
Button area
7.
Rotary switch for selecting function
8.
Test button
9.
Safety alligator clip
10.
Standard test wires
11.
Auxiliary earthing rods
12.
Simple test wires
13.
Interface of testing wires
VI
．
Measuring Principle
1. Ground voltage measurement uses average rectification.
2. The grounding resistance measurement adopts the rated current change
pole method, that is, the alternating current rated current I flowing between the
measuring object E ground electrode and the H current electrode, to obtain
the potential difference V of the E ground electrode and S voltage electrode,
and according to the formula R=V/ I Calculate the ground resistance value R.
In order to ensure the accuracy of the test, a four-wire method was designed
to increase the FR auxiliary ground. During actual testing, FR and E were
clamped at the same point of the grounding body. The four-wire test can
eliminate the influence of the contact resistance (usually dirt or rust) on the
measured grounding body, auxiliary grounding rod, test clip, and the input
interface of the instrument to the measurement, and can eliminate the
influence of the wire resistance on the measurement, more precision.
3
．
It
’
s operating error(B) is an error obtained within the rated operating
conditions, and calculated with the intrinsic error(A) and the error(E) due to
variations.
