AEMC 6471 - Page 83

Ground Resistance Tester Model 6471 81
E : terminal E (X) - earth socket; current measurement return
terminal
EARTH : earth measurement (3 or 4 poles)
EARTH COUPLING : coupling measurement between two earth sockets
ES : ES (Xv) terminal (measurement potential socket for
calculating earth resistance)
H : H (Z) terminal (measurement current injection terminal)
I-Act
(1)
: external current circulating at present between the instrument
terminals
I
ES
: current measured by the clamp connected to the ES terminal
(selective earth measurement with clamp)
I
H-E
: measurement current circulating between the H and E
terminals
NOISE : indicates the presence of external interference causing
misrepresentation of the earth or resistivity measurement
R : average resistance calculated from R+ and R-
R+ : resistance measured with a positive current circulation from
terminal H to E
R- : resistance measured with a negative current circulation from
terminal H to E
R-Act
(1)
: resistance currently calculated from values U-Act and I-Act
R
1
: rst value measured to calculate the coupling between 2 earth
sockets (R
1
= R
A
+ R
C
)
R
2
: second value measured to calculate the coupling between 2
earth sockets (R
2
= R
b
+ R
C
)
R
1-2
: third value measured to calculate the coupling between 2
earth sockets (R
1-2
= R
A
+ R
b
)
R
A
: rst earth value calculated (R
A
= R
1
- R
C
)
R
b
: second earth value calculated (R
b
= R
1
- R
C
)
R
C
: coupling resistance between earths R
A
and R
b
(R
c
= (R
1
+ R
2
– R
1-2
) / 2)
R
E
: earth resistance connected to terminal E
R
H
: resistance of the stake connected to terminal H
R
LOOP
: resistance of the earth loop measured with the "2 clamps"
function
R
PASS
: value of the R-Act resistance (PASS for "passive"
measurement with interference current circulating in the
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