MRU-120
– USER MANUAL
39
Measurement of earth resistance
– 3-pole method with additional clamp (R
E
3P+C)
Range of measurement in accordance with IEC 61557-5: 0,44
... 1999
Range
Resolution
Accuracy
0,00...19,99
Ω
0,01
Ω
±(8% m.v. + 3 digits)
20,0...199,9
Ω
0,1
Ω
200....1999
Ω
1
Ω
Measurement of multiple earth resistance
– two-clamp method (2C)
Range
Resolution
Accuracy
0,00...19,99
Ω
0,01
Ω
±(10% m.v. + 3 digits)
20,0...149,9
Ω
0,1
Ω
±(20% m.v. + 3 digits)
Earth resistivity measurement (
ρ)
The measurem
ent method: Wenner’s, ρ = 2πLR
E
Range
Resolution
Accuracy
0,0..199,9
Ωm
0,1
Ωm
Depends on the basic
uncertainty of the R
E
4P measurement
but
not less than ±1 digit.
200..1999
Ωm
1
Ωm
2,00..19,99
kΩm
0,01
kΩm
20,0..99,9
kΩm
0,1
kΩm
100..999
kΩm
1 k
Ωm
distance between measurement electrodes (L): 1...50 m
Other technical data
a) type of insulation in accordance with EN 61010-1 and IEC 61557 ....................................... double
b) measurement category in accordance with EN 61010-1 (for 2000 m a.s.l.) ..................... IV 300 V
c) protection grade of the casing in accordance with EN 60529 ................................................... IP54
d) maximum interference voltage AC + DC at which a measurement may be performed............. 24 V
e) maximum measured interference voltage .............................................................................. 100 V
f) maximum interference current at which a measurement of the earth resistance by means of the
clamp method is performed ................................................................................................ 3 A rms
g) frequency of the measurement current
▪ for 50 Hz mains ................................................................................................................. 125 Hz
▪ for 60 Hz mains ................................................................................................................. 150 Hz
h) measurement voltage and current for 2P .......................... U < 24 V RMS, I
≥ 200 mA for R ≤ 60
i)
measurement voltage for R
E
3P, R
E
4P ............................................................................ 25 or 50 V
j)
measurement current (short-circuit current) for R
E
3P, R
E
4P ............................................. >200 mA
k) maximum resistance of measurement electrodes ................................................................. 20 k
l)
signalling of insufficient clamp current for ..........................................................................
≤0.5 mA
m) power supply of the meter ............................ accumulator package type SONEL NiMH 4.8 V 3 Ah
n) parameters of AC adapter for the battery charge ..............................
100 V…240 V, 50 Hz…60 Hz
o) number of measurements for 2P ................................................ >1100 (1
, 2 measurement/min)
p) number of measurements for R
E
3P, R
E
4P... >800 (R
E
=10
, R
H
=R
S
=100
, 2 measurement/min)
q) duration of a resistance measurement by means of the two-pole method ............................... <6 s
r) duration of a resistance and resistivity measurement by means of other methods .................. <8 s
s) dimensions ....................................................................................................... 288 x 223 x 75 mm
t) mass of the meter with accumulators ................................................................................ ca. 2 kg
u) working temperature ...................................................................................................... -10..+50
C
Summary of Contents for MRU-120
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