28
Digital Ground Resistance Tester Model 4500
either side of the initial Y setting are most likely to be within the established
tolerance band. This tolerance band is defined by the user and expressed
as a percent of the initial reading: ± 2%, ± 5%, ± 10%, etc.
Resistance
Distance from Y to Ground Electrode
Effective
Resistance
Areas Do
Not Overlap
X
Y
Z
Ground
Electrode
Under Test
Auxiliary
Potential
Electrode
Auxiliary
Current
Electrode
D
62% of D
Resistance of
Auxiliary Current
Electrode
Resistance of Earth Electrode
Figure 14
4.4.1 Auxiliary Electrode Spacing
No definite distance between X and Z can be given, since this distance is
relative to the diameter of the electrode tested, its length, the homogeneity
of the soil tested, and particularly, the effective resistance areas. However,
an approximate distance may be determined from the following chart
which is given for a homogeneous soil and an electrode of 1" in diameter.
(For a diameter of 1/2", reduce the distance by 10%; for a diameter of 2"
increase the distance by 10%.)
Approximate distance to auxiliary electrodes using the 62% method:
Depth Driven
Distance to Y
Distance to Z
6 ft.
45 ft.
72 ft.
8 ft.
50 ft.
80 ft.
10 ft.
55 ft.
88 ft.
12 ft.
60 ft.
96 ft.
18 ft.
71 ft.
115 ft.
20 ft.
74 ft.
120 ft.
30 ft.
86 ft.
140 ft.
Содержание 450.100
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