AEMC 6471 - Power; Mechanical

Ground Resistance Tester Model 6471 21
3.2.6 Soil Resistivity Measurement ρ
Measuringmethod: Voltage/Current measurement (EN 61557 part 5)
Opencircuitvoltage: 16 or 32Vrms square wave
Testfrequency: Selectable from 41 to 128Hz (see table in § 6.2)
Shortcircuitcurrent: > 200mAAC
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
, R
ES
, R
E
:100kΩ
Calculationformula,Wenner: ρ
W
= 2p d R
S-ES
Calculationformula,Schlumberger: ρ
S
= (p (d2 - (A/2)²) / A) R
S-ES
Maximum value of ρ: 999kΩm (display in kΩft is not possible)
Measuringtime: ShortpushonSTART:approx. 8 s for rst value of R
S-ES
at
128 Hz, then 3 measurements per s.
LongpushonSTART: approx. 20 s for rst value of R
S-ES
at
128 Hz, then 3 measurements per s.
Measurement
Range
0.00 to
9.99Ω
10.0 to
99.9Ω
100 to
999Ω
1.00 to
9.99kΩ
10.0 to
99.9kΩ
Resolution 0.01Ω 0.1Ω 1Ω 10Ω 100Ω
Intrinsic error ± (2% + 1ct)
The intrinsic error specied refers to reference conditions with a test voltage of
32V, test frequency of 128Hz, R
ρ-H
, R
ρ-S
, R
ρ-ES
and R
ρ-E
= 1kΩ, no external voltage.
Operating conditions : R
S-ES
< 3 x R
ρ
-H
and: Operating error for R
S-ES
R
electrode
≤ 100kΩ
R
electrode
/ R
S-ES
≤ 2000
± (7% + 2cts)
R
electrode
≤ 50kΩ
R
electrode
/ R
S-ES
≤ 10,000
± (15% + 3cts)
R
electrode
≤ 10kΩ
R
electrode
/ R
S-ES
≤ 20,000
± (20% + 1ct)
R
rod
is the resistance of the earth rods R
ρ
-E
, R
ρ
-ES
, R
ρ
-E
, R
ρ
-H
assumed to be identi-
cal.
Note: With a test voltage U
OUT
of 16V, halve the value of R
rod
.
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