MRU-120
– USER MANUAL
41
10.2.4 Influence of the auxiliary electrodes upon earth resistance meas-
urements for function
ρ
Uncertainty [%]
)
10
4
10
2
,
3
30000
(
2
2
4
7
S
H
E
S
H
R
R
R
R
R
R
E
[Ω], R
S
[Ω] and R
H
[Ω] are values which are displayed by the device.
10.2.5 Influence of the interference current I
l
upon the result of the earth
resistance measurement for method R
E
3P+C
The MRU-120 meter may perform a measurement, if the value of the interference current does
not exceed 3 A RMS and the frequency complies with the value set in the MENU.
R
E
U
wy
Uncertainty [
]
≤50
25 V
)
10
5
(
2
3
l
E
I
R
50 V
)
10
5
,
2
(
2
3
l
E
I
R
>50
25 V
)
10
70
(
2
2
6
l
E
I
R
50 V
)
10
50
(
2
2
6
l
E
I
R
If the interference current exceeds 3 A the possibility of measurement is blocked.
10.2.6 Influence of interference current on the result of the earth resistance
measurement for two-clamp method (2C)
The MRU-120 meter may perform a measurement, if the value of the interference current does
not exceed 3 A RMS and the frequency complies with the value set in the MENU.
R
E
Uncertainty [
Ω]
0,00...4,99
Ω
within the range of the basic uncertainty
5,00...19,9
Ω
)
10
5
(
3
2
3
l
E
I
R
20,0...149,9
Ω
)
10
6
(
3
2
2
l
E
I
R
If the interference current exceeds 3 A the possibility of measurement is blocked.
10.2.7 Influence of the relation of the resistance measured with clamp for
the multiple earthing branch to the resultant resistance (R
E
3P+C)
R
C
Uncertainty [
Ω]
≤99,9 Ω
)
10
3
(
2
3
w
C
R
R
>99,9
Ω
)
10
6
(
2
2
w
C
R
R
R
C
[Ω] is the value of the resistance measured with clamps for the branch displayed by the device,
and R
W
[Ω] is the value of the resultant multiple earth resistance.
Summary of Contents for MRU-120
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