Ground Resistance Tester Model 6471
19
4-Pole m
Ω
measurement
Measurement
Range
0.020 to
9.999
Ω
10.00 to
99.99
Ω
100.0 to
999.9
Ω
1.000 to
9.999k
Ω
10.00 to
99.99k
Ω
Resolution
0.001
Ω
0.01
Ω
0.1
Ω
1
Ω
10
Ω
Intrinsic error
± (2% + 2cts)
Operating error
± (5% + 5cts)
3.2.5 AC Earth/Ground Resistance Measurements
Measuring method:
Voltage/Current measurement (EN 61557 part 5)
Open circuit voltage:
16 or 32Vrms square wave (if current > 240mA the output
voltage is reduced to 10Vrms)
Test frequency:
Selectable from 41 to 513Hz (see table in § 6.2)
Short circuit current:
> 200mA
AC
Noise suppression:
> 80 dB for frequencies 20% or more above or below the
test frequency
Max. overload:
250Vrms
Max. value for R
H
& R
S
:
100k
Ω
Measuring time:
Short push on START:
approx. 7 s for first value of R
E
at
128Hz, then 3 measurements per s.
Long push on START:
approx. 15 s for first value of R
E
at
128Hz, then 3 measurements per s.
The following error indications refer to reference conditions with a test voltage of
32V, test frequency of 128Hz, R
H
and R
S
= 1k
Ω
, no external voltage.
The operating error of AC resistance measurements can be less than that speci
-
fied for voltage or current because frequency characteristics of the voltage channel
are matched to those of the current channel.
Measurement of auxiliary electrodes R
H
, R
S
, R
ES
, R
E
Measurement
Range
0.14 to
9.99
Ω
10.0 to
99.9
Ω
100 to
999
Ω
1.00 to
9.99k
Ω
10.0 to
99.9k
Ω
Resolution
0.1
Ω
0.1
Ω
1
Ω
10
Ω
100
Ω
Operating error
± (10% + 2cts)
The
START
button must be pressed for more than 2 s. For frequencies between
41 and 256Hz, the resistance of the auxiliary earth electrodes is measured at the
test frequency set. At higher frequencies the resistance is measured at 256Hz.
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