MRU-200
● MRU-200-GPS – USER MANUAL
56
10.2.7 Influence of interference current on the result of the earth resistance
measurement for two-clamp method (2C)
The MRU-200 / MRU-200-GPS meter may perform a measurement, if the value of the interfer-
ence 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 accuracy
5.00
…19.9 Ω
)
10
5
(
3
2
3
zakl
E
I
R
20.0
…149.9 Ω
)
10
6
(
3
2
2
zakl
E
I
R
If the interference current exceeds 3 A the possibility of measurement is blocked.
10.2.8 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.
10.2.9 Additional uncertainties in accordance with IEC 61557-4 (2P)
Influencing factor
Symbol
Additional uncertainty
Location
E
1
0%
Power supply voltage
E
2
0% (
BAT
not displayed)
Temperature
E
3
R
≤3,999Ω
±0,3digits/°C
R>3,999
Ω and
<1k
Ω
±0,2digits/°C
R≥1kΩ
±0,07%/°C
±0,2 digits/°C
10.2.10 Additional uncertainties in accordance with IEC 61557-5 (R
E
3P,
R
E
4P, R
E
3P+C)
Influencing factor
Symbol
Additional uncertainty
Location
E
1
0%
Power supply voltage
E
2
0% (
BAT
not displayed)
Temperature
E
3
R
≤3,999 Ω
±0,3 digits/°C
R>3,999
Ω and
<1 k
Ω
±0,2 digits/°C
R≥1 kΩ
±0,07%/°C
±0,2 digits/°C
Serial interference voltage
E
4
In accordance with formula In 10.2.1
(U
z
=3 V 50/60/400/16 2/3 Hz)
Resistance of electrodes and
auxiliary earth electrodes
E
5
In accordance with the formula in
10.2.3
