AEMC instruments 6471 User manual

WITH AEMC
®
INSTRUMENTS
GROUND RESISTANCE TESTERS
Ground Resistance Tester
Model 6471
ENGLISH
User Manual

Copyright©Chauvin Arnoux®, Inc. d.b.a. AEMC®Instruments. All rights reserved.
No part of this documentation may be reproduced in any form or by any means (including electronic
storage and retrieval or translation into any other language) without prior agreement and written consent
from Chauvin Arnoux®, Inc., as governed by United States and International copyright laws.
Chauvin Arnoux®, Inc. d.b.a. AEMC®Instruments
15 Faraday Drive • Dover, NH 03820 USA
Tel: [phone] or [phone] • Fax: [phone]
This documentation is provided “as is,” without warranty of any kind, express, implied, or otherwise.
Chauvin Arnoux®, Inc. has made every reasonable e󰀨ort to ensure that this documentation is accurate;
but does not warrant the accuracy or completeness of the text, graphics, or other information contained
in this documentation. Chauvin Arnoux®, Inc. shall not be liable for any damages, special, indirect,
incidental, or inconsequential; including (but not limited to) physical, emotional or monetary damages
due to lost revenues or lost prots that may result from the use of this documentation, whether or not the
user of the documentation has been advised of the possibility of such damages.

Chauvin Arnoux®, Inc.
d.b.a AEMC®Instruments
www.aemc.com
Statement of Compliance
Chauvin Arnoux®, Inc. d.b.a. AEMC® Instruments
certies that this instrument has been calibrated
using standards and instruments traceable to
international standards.
We guarantee that at the time of shipping your
instrument has met the instrument’s published
specications.
An NIST traceable certicate may be requested
at the time of purchase, or obtained by returning
the instrument to our repair and calibration
facility, for a nominal charge.
The recommended calibration interval for this
instrument is 12 months and begins on the date of
receipt by the customer. For recalibration, please
use our calibration services. Refer to our repair and
calibration section at www.aemc.com/calibration.
Serial #:
Catalog #: 2135.45, 2135.49, 2135.50, 2135.60
& 2135.61
Model #: 6471
Please ll in the appropriate date as indicated:
Date Received:
Date Calibration Due:

TABLE OF CONTENTS
1. INTRODUCTION..................................................................7
1.1 PRECAUTIONS FOR USE ........................................................ 8
1.2 BAT TERY .................................................................................... 9
1.3 RECEIVING YOUR SHIPMENT................................................ 9
1.4 ORDERING INFORMATION................................................... 10
1.4.1 Accessories ...................................................................... 10
1.4.2 Replacement Parts........................................................... 11
2. PRODUCT FEATURES..................................................... 12
2.1 DESCRIPTION ......................................................................... 12
2.2 KEY FEATURES ...................................................................... 13
2.3 CONTROL FEATURES ........................................................... 13
2.4 DISPL AY ................................................................................... 14
2.5 BUTTON FUNCTIONS ............................................................ 17
3. SPECIFICATIONS ............................................................. 18
3.1 REFERENCE CONDITIONS................................................... 18
3.2 ELECTRICAL ........................................................................... 18
3.2.1 Frequency Measurements................................................ 18
3.2.2 Voltage Measurements .................................................... 18
3.2.2.1 External Voltage Measurements............................... 19
3.2.3 Current Measurements .................................................... 19
3.2.3.1 External Current Measurements............................... 19
3.2.4 DC Resistance Measurements ........................................ 20
3.2.5 AC Earth/Ground Resistance Measurements.................. 21
3.2.6 Soil Resistivity Measurement ρ...................................... 23
3.2.7 Earth/Ground Measurements with 2 Clamps ................... 24
3.3 DATA STOR AGE ...................................................................... 25
3.4 POWER..................................................................................... 25
3.5 MECHANICAL.......................................................................... 25
3.6 ENVIRONMENTAL .................................................................. 25
3.7 SAFET Y .................................................................................... 26
4. OPER ATION ......................................................................27
4.1 GENERAL OPERATING INSTRUCTIONS ............................ 27
4.1.1 Automatic Mode ................................................................ 27
4.1.2 Manual (Expert) Mode ...................................................... 27
4.2 INSTRUMENT CONFIGURATION (SET-UP MODE)............ 28

5. AUTOMATIC MODE..........................................................29
5.1 SWITCHING THE TEST VOLTAGE ........................................ 29
5.2 RESISTANCE MEASUREMENT MΩ(2-WIRE)..................... 29
5.2.1 Lead Compensation Measurement .................................. 30
5.2.2 Alarm Function ................................................................. 31
5.3 RESISTANCE MEASUREMENT MΩ (4-WIRE)..................... 32
5.4 EARTH/GROUND MEASUREMENT (3-POLE)..................... 33
5.4.1 62 % Method..................................................................... 33
5.4.2 Full Method....................................................................... 35
5.4.3 Recommendations for a Reliable Measurement .............. 36
5.5 EARTH/GROUND MEASUREMENT (4-POLE)..................... 37
5.5.1 Measurement without a Clamp......................................... 37
5.5.2 Measurements with a Clamp............................................ 38
5.6 SOIL RESISTIVITY MEASUREMENTS (ΡPOSITION)........ 40
5.6.1 Advantages and Disadvantages of Wenner and
Schlumberger ............................................................................ 40
5.6.2 Changing the Measurement Method................................ 41
5.6.3 Programming the Distance for Electrode Placement ....... 42
5.6.4 Wenner Method ................................................................ 42
5.6.5 Schlumberger Method...................................................... 43
5.7 EARTH/GROUND MEASUREMENTS WITH
TWO CLAMPS ............................................................................... 45
6. MANUAL MODE................................................................ 47
6.1 SWITCHING THE TEST VOLTAGE ........................................ 47
6.2 MEASUREMENT FREQUENCY SELECTION ...................... 47
6.3 MANUAL SETTINGS FOR MΩ MEASUREMENTS ............. 48
6.3.1 Continuity Test .................................................................. 48
6.4 3-POLE EARTH/GROUND MEASUREMENTS
& COUPLING..................................................................................... 48
6.4.1 3-Pole Earth/Ground Measurements ............................... 48
6.4.2 Earth/Ground Coupling Measurements ........................... 49
6.5 4-POLE EARTH/GROUND MEASUREMENTS .................... 50
6.6 SOIL RESISTIVITY MEASUREMENTS................................. 50
6.7 MEASUREMENTS WITH TWO CLAMPS ............................. 51
6.8 SMOOTHING........................................................................... 51

7. MEMORY FUNCTION .......................................................52
7.1 SAVING MEASUREMENTS INTO MEMORY ........................ 52
7.2 RECALLING MEASUREMENTS FROM MEMORY .............. 53
7.3 ERASING MEASUREMENTS FROM MEMORY................... 53
7.3.1 Erasing All Measurements ................................................ 53
7.3.2 Erasing Selective Measurements ..................................... 53
8. DATAVIEW®SOFTWARE.................................................55
8.1 INSTALLING DATAVIEW®.................................................................................................. 55
8.2 GROUND TESTER CONTROL PANEL ................................. 56
9. MAINTENANCE................................................................. 57
9.1 M A I N T E N A N C E ....................................................................... 57
9.2 CLEANING ............................................................................... 57
9.3 FUSE REPLACEMENT ........................................................... 57
9.4 CHARGING THE BATTERY.................................................... 59
9.5 REPLACING THE BATTERY .................................................. 60
10. TROUBLESHOOTING & MAINTENANCE....................62
10.1 ERROR REPORTING ............................................................ 62
10.1.1 Electrode Resistance Too High....................................... 62
10.1.2 Out of Range................................................................... 62
10.1.3 Misconnection ................................................................ 62
10.1.4 Out of Limits Indicators ................................................... 63
10.1.5 Error Messages............................................................... 64
10.2 REPAIR AND CALIBRATION ............................................... 65
10.3 TECHNICAL ASSISTANCE................................................... 66
10.4 LIMITED WARRANTY........................................................... 66
10.4.1 Warranty Repairs............................................................ 67
APPENDIX A: GLOSSARY OF TERMS..............................68
BASIC TERMINOLOGIES............................................................. 68
GLOSSARY .................................................................................... 70

1. INTRODUCTION
Thank you for purchasing an AEMC®Instruments Ground Tester Model 6471.
For the best results from your instrument and for your safety, you must read the
enclosed operating instructions carefully and comply with the precautions for use.
Only qualied and trained operators should use this product.
Symbols and Denitions
Signies that the instrument is protected by double or reinforced insulation
CAUTION - Risk of Danger! Indicates a WARNING. Whenever this symbol
is present, the operator must refer to the user manual before operation
Indicates a risk of electric shock. The voltage at the parts marked with this
symbol may be dangerous
Indicates Important information to acknowledge
This product complies with the Low Voltage & Electromagnetic Compatibility
European directives
The UKCA marking certies that the product is compliant with the require-
ments that apply in the United Kingdom, specically regarding Low-Voltage
Safety, Electromagnetic Compatibility, and the Restriction of Hazardous
Substances.
Ground/Earth
The product has been declared recyclable
In the European Union, this product is subject to a separate collection
system for recycling electrical and electronic components in accordance with
directive WEEE 2012/19/EU
Denition of Measurement Categories (CAT)
CAT IV: Corresponds to measurements performed at the primary electrical
supply (< 1000 V).
Example: primary overcurrent protection devices, ripple control units,
and meters.
CAT III: Corresponds to measurements performed in the building installation
at the distribution level.
Example: hardwired equipment in xed installation and circuit
breakers.
CAT II: Corresponds to measurements performed on circuits directly
connected to the electrical distribution system.
Example: measurements on household appliances and portable tools.

8 Ground Resistance Tester Model 6471 - User Manual
1.1 PRECAUTIONS FOR USE
These safety warnings are provided to ensure the safety of personnel. Please
read and comply with these precautions:
■This instrument is protected from accidental voltages of not more than
50 V with respect to earth in measurement CAT IV. The guaranteed level of
protection of this equipment may be compromised if used in a manner not
specied by the manufacturer.
■Safety is the responsibility of the operator.
■All metal objects or wires connected to the electrical system should be
assumed to be lethal until tested. Grounding systems are no exception.
■Never exceed the maximum rated voltage and current, and the measurement
category.
■Never exceed the protection limits, and always comply with the conditions and
place of use, indicated in the specications.
■Do not use the instrument or its accessories if they appear damaged.
■Use accessories that have overvoltage category and service voltages greater
than or equal to those of the instrument (CAT IV 50 V). Use only accessories
that comply with safety standards (IEC 61010).
■Wear the appropriate protective gear (insulating boots and gloves).
■Check that no terminal is connected and the switch is set to OFF before
opening the device.
■Use only the charging unit supplied with the instrument to charge the battery.
■Troubleshooting and metrological verication procedures must only be
performed by qualied, approved personnel, or the factory.
NOTE: The potentials on the various rods used for an earth
measurement may be di󰀨erent if a nearby electrical installation is
defective or certain weather conditions prevail (thunderstorms).
It is up to the operator to decide whether to continue or postpone
measurements in these situations.

Ground Resistance Tester Model 6471 - User Manual 9
1.2 BATTERY
The device is equipped with a NiMH battery. This technology has several
advantages:
■Long battery life for a limited volume and weight;
■Signicantly reduced memory e󰀨ect, which means you can charge the battery
even if it is not completely discharged;
■Environmentally friendly with no polluting material, such as lead or cadmium,
in accordance with applicable regulations.
The battery may be completely discharged after prolonged storage. If the battery
is completely discharged, it must be fully charged. The device may not work
during part of the charging. Charging a completely discharged battery may take
several hours.
NOTE: If the battery is completely discharged, at least 5 charge/
discharge cycles will be necessary for the battery to regain 95 % of
capacity. Refer to the battery data sheet delivered with the device.
To optimize the use of your battery and extend the battery e󰀨ective life:
■Only use the charger supplied with your instrument. Use of another charger
may be dangerous.
■Charge the device only at temperatures between (50 and 104) °F (10 and 40) °C.
■Comply with the conditions for use dened in the user manual.
■Comply with the storage conditions specied in the user manual.
NiMH technology allows a limited number of charge/discharge cycles depending
signicantly on:
■The conditions of use.
■The charging conditions.
Please refer to § 9.5 for correct replacement of the battery.
Do not dispose of the battery pack with other solid waste. Used batteries must
be entrusted to a qualied recycling company or to a company specialized in
processing hazardous materials.
1.3 RECEIVING YOUR SHIPMENT
Upon receiving your shipment, make sure that the contents are consistent with the
packing list. Notify your distributor of any missing items. If the equipment appears
to be damaged, le a claim immediately with the carrier and notify your distributor
at once, giving a detailed description of any damage. Save the damaged packing
container to substantiate your claim.

10 Ground Resistance Tester Model 6471 - User Manual
1.4 ORDERING INFORMATION
Ground Resistance Tester Model 6471 (no probes included) ..........Cat. #2135.48
Includes (1) carrying bag 110/240 V power adapter with US power cord, optical
USB cable, rechargeable NiMH battery, and a USB stick with DataView®
software, ground tester workbook and user manual.
Ground Tester Model 6471 (probes included) .................................Cat. #2135.49
Includes carrying bag, set of (2) SR182 current probes, 110/240 V power
adapter with US power cord, optical USB cable, rechargeable NiMH battery, and
a USB stick with DataView®software, ground tester workbook and user manual.
Ground Tester Model 6471 Kit (300 ft - probes included) .........Cat. #2135.50
Includes meter, carrying bag, (2) 300 ft color-coded leads on spools (red/blue),
(2) 100 ft color-coded leads (hand-tied, green/black), (2) 5 ft color-coded leads
(red/blue), set of (2) SR182 current probes, 110/240 V power adapter with
US power cord, optical USB cable, (4) T-shaped auxiliary ground electrodes,
set of (5) spaded lugs, (1) 100 ft tape measure, rechargeable NiMH battery, and
a USB stick with DataView®software, ground tester workbook and user manual.
Ground Tester Model 6471 Kit (300 ft - no probes included) .... Cat. #2135.60
Includes meter, (2) carrying bags, (2) 300 ft color-coded leads on
spools (red/blue), (2) 100 ft color-coded leads (hand-tied, green/black),
(2) 5 ft color-coded leads (red/blue), 110/240 V power adapter with US power
cord, optical USB cable, (4) T-shaped auxiliary ground electrodes,
set of (5) spaded lugs, (1) 100 ft tape measure, rechargeable NiMH battery, and
a USB stick with DataView®software, ground tester workbook and user manual.
Ground Tester Model 6471 Kit (500 ft - no probes included).... Cat. #2135.61
Includes meter, (2) carrying bags, (2) 500 ft color-coded leads on
spools (red/blue), (2) 100 ft color-coded leads (hand-tied, green/black),
(2) 5 ft color-coded leads (red/blue), 110/240 V power adapter with US power
cord, optical USB cable, (4) T-shaped auxiliary ground electrodes,
set of (5) spaded lugs, (1) 100 ft tape measure, rechargeable NiMH battery, and
a USB stick with DataView®software, ground tester workbook and user manual.
1.4.1 Accessories
Test Kit for 3-Pole (3-Point) Testing (150 ft)................................ Cat. #2135.35
Includes carrying bag, (2) 150 ft color-coded leads on spools (red/blue),
(1) 30 ft lead (green), (2) 5 ft color-coded leads (red/blue), (2) T-shaped auxiliary
ground electrodes, set of (5) spaded lugs and (1) 100 ft tape measure.
Test Kit for 4-Pole (4-Point) Testing (300 ft)................................ Cat. #2135.36
Includes carrying bag, (2) 300 ft color-coded leads on spools (red/blue),
(2) 100 ft color-coded leads (hand-tied, green/black), (2) 5 ft color-coded
leads (red/blue), (4) T-shaped auxiliary ground electrodes, set of (5) spaded lugs
and (1) 100 ft tape measure.

Ground Resistance Tester Model 6471 - User Manual 11
Test Kit for 4-Pole (4-Point) Testing (500 ft)................................ Cat. #2135.37
Includes (1) carrying bag, (2) 500 ft color-coded leads on spools (red/blue),
(2) 100 ft color-coded leads (hand-tied, green/black), (1) 30 ft lead (green),
(2) 5 ft color-coded leads (red/blue), (4) T-shaped auxiliary ground electrodes,
set of (5) spaded lugs and (1) 100 ft tape measure.
Test Kit for 3-Pole (3-Point) Testing
(Supplemental for 4-Pole (4-Point) Testing)................................ Cat. #2135.38
Includes (1) carrying bag, (2) 100 ft color-coded leads (hand-tied, green/black),
(1) 30 ft lead (green), (2) T-shaped auxiliary ground electrodes,
set of (5) spaded lugs and (1) 100 ft tape measure.
1.4.2 Replacement Parts
Extra Large Classic Tool Bag........................................................... Cat. #2133.73
Tape Measure - AEMC®Instruments (100 ft)................................... Cat. #2130.60
Ground Tester DVD/Workbook Set..................................................Cat. #2130.64
Set of two, 14.5 in T-shaped Auxiliary Ground Electrodes .............. Cat. #2135.39
Replacement - Carrying Bag for Ground Tester .............................. Cat. #2135.40
Optical USB Cable ........................................................................... Cat. #2135.41
Inverter – 12 VDC to 120 VAC 200 Watt for vehicle use.................... Cat. #2135.43
AC Current Probe Model MN82 ....................................................... Cat. #2135.71
AC Current Probe Model SR182...................................................... Cat. #2135.72
Replacement - Fuse, set of (5), 0.63 A 250 V 5 x 10 1.5 kA............ Cat. #2135.81
Safety Alligator Clip - Black (Rated 600 V CAT IV, 10 A)................. Cat. #2140.53
Safety Alligator Clip - Green (Rated 600 V CAT IV, 10 A) ............... Cat. #2140.69
Replacement - Battery, Rechargeable NiMH 9.6 V .........................Cat. #2960.21
Replacement - Power Adapter 110/240 V & Power Cord 115 V US....... Cat. #5000.13
Replacement - Power Cord 115 V US Plug...................................... Cat. #5000.14
Order Accessories and Replacement Parts Directly Online
Check our Storefront at www.aemc.com/store for availability

12 Ground Resistance Tester Model 6471 - User Manual
2. PRODUCT FEATURES
2.1 DESCRIPTION
The Ground Resistance Tester Model 6471 is a portable measurement
instrument designed to measure:
■Ground Resistance with 2 clamps (no auxiliary rods needed)
■Bond/Connection Resistance (2-Pole and 4-Pole Kelvin sensing)
■Ground Resistance (3-Pole or 4-Pole)
■Ground Coupling Resistance
■Selective Ground Resistance
■Soil Resistivity (Wenner or Schlumberger method)
The Model 6471 measures from (0.01 to 99.99) kΩand is auto-ranging,
automatically seeking out the optimum measurement range, test frequency and
test current.
Easy-to-use - Simply connect the leads, select the test mode, press Start and
read the results. Up to 512 test results can be stored in internal memory for later
recall to the display or downloaded to a PC via DataView®software.
The large LCD is easy-to-read and indicates ground electrode resistance, test
voltage, current and frequency as well as individual electrode resistance, battery
status and more.
The Model 6471 is CAT IV rated to 50 V and is over voltage protected to more
than 250 VAC against accidental connection to live circuits. The voltage is
also displayed on screen. In the event of a system fault, the Model 6471 can
withstand 250 VAC.
Additional features of the Model 6471 include a heavy-duty eld case sealed
against dust and water when closed (the test button is also sealed against the
elements); manual and automatic test frequency selection from (41 to 513) Hz;
4-Pole Soil Resistivity test methods and user selectable 2-Pole or 4-Pole Bond
Resistance test method.
The Model 6471 is powered by 9.6 V, 3.5 A·h NiMH rechargeable batteries. An
external recharger powered from 120/230 V, 50/60 Hz is included and provides
for testing while charging.
The Ground Resistance Tester Model 6471 is rugged, easy-to-use and ideal
for maintenance crews performing numerous tests. It exceeds mechanical and
safety specications for shock, vibration and drop tests per IEC standards. The
adjustable test frequency provides for rejection of high levels of interference,
allowing it to be used under di󰀩cult conditions such as high stray currents that
a󰀨ect accuracy.

Ground Resistance Tester Model 6471 - User Manual 13
2.2 KEY FEATURES
■Ground Resistance testing using the 2 clamp method (no auxiliary rods
needed)
■2- and 4-Pole Bond Resistance/Continuity measurement (DC Resistance)
with automatic polarity reversal
■4-Pole Soil Resistivity measurement with automatic calculation of Rho (ρ) and
user selection of the Wenner or Schlumberger test method
■3-Pole Earth Coupling measurement
■Manual and Automatic frequency scan from (41 to 513) Hz for optimum test
accuracy in electrically noisy environments
■Selectable test voltage of 16 V or 32 V up to 250 mA of test current
■Auto-o󰀨 power management
■Automatic recognition of all electrode connections and their resistance value
■Stores up to 512 complete test results in internal memory
■Optically isolated USB communication
■Remote set up and operation of all measurements using DataView®software
■Rechargeable NiMH batteries from wall charger or vehicle power
■Rugged dustproof and rainproof eld case – IP53 rated in closed position
■Grounding standards IEC 61557 parts 4 and 5 compliant
■Includes DataView®software for data storage, real-time display, analysis,
report generation and system conguration
2.3 CONTROL FEATURES
Figure 2-1
GROUND TESTER
MODEL 6471
Ω
2 3 4
1
5
7
6

14 Ground Resistance Tester Model 6471 - User Manual
1. Four terminals: H (Z) (auxiliary electrode), S (Y) (electrode), ES (Xv) (earth/
ground electrode) and E (X) (earth/ground electrode)
All terminals accept 4 mm Ø banana plugs. Terminals H (Z) and ES (Xv) also
accept special plugs for current clamps. S (Y) will take a shielded cable.
2. Connector for charging the battery (see § 9.4).
3. 256 segment multi-line backlit LCD (see § 2.4).
4. Connector for an optical interface to a PC. Either an RS-232 or USB
connection can be used (see § 8 - DataView®).
5. Rotary switch: OFF position, 5 measurement functions (see § 5 and § 6) and
SET-UP function (see § 4.2).
6. START/STOP button: Starts the measurement and compensates for the leads
(in the mΩmeasurement function - see § 5.2.1).
7. Six function buttons (see § 2.5).
2.4 DISPLAY
NOTE 1: External voltages will be displayed only on the small displays
(A2 and A3) without the view of the main display (A1). This helps to
rapidly recognize that these are measurements of external voltages.
NOTE 2: Backlight: The backlight turns ON automatically when entering
a function and turns OFF after the function is complete.
Press the DISPLAY button to turn it back ON.
NOTE 3: In the Set-up mode, pressing the DISPLAY button also selects
the next congurable parameter.

Ground Resistance Tester Model 6471 - User Manual 15
Figure 2-2
A1 Top main display
A2 Middle small display
A3 Bottom small display
If this symbol blinks during a passive measurement, a voltage of
more than 42 V is present at the tester’s inputs.
If this symbol blinks during an active measurement, the limits of
use have been exceeded.
If the symbol appears constant during an active measurement,
the values to be measured are unstable.
Warning buzzer is activated
> or <
A blinking symbol > (greater than) or < (less than) indicates that
the measurement range is exceeded.
If both symbols are blinking during a passive measurement, the
values of voltage and/or current are too small and are beyond
the limits of use. The resistance RPASS displayed by the tester
is then highly uncertain.
If both symbols are blinking during an active measurement, the
values to be measured are strongly varying (remedy: switch on
smoothing of measured values with SMOOTH function).
Indicates the battery charge condition; the segments represent
the energy.
EARTH
COUPLING
Indicates whether the 3-Pole EARTH measurement or the
EARTH COUPLING measurement has been selected.
S x 1/10 Symbol not used in Model 6471
A1
A2
A3

16 Ground Resistance Tester Model 6471 - User Manual
Symbol not used in Model 6471
Symbol not used in Model 6471
OBJ:TEST Object and test number for storage in memory.
Indicates lead compensation for 2-Pole measurement is active
DISTANCE
If blinking, indicates the value is ready to be overwritten with
a new value or that a new value will be entered. If more than
one value has to be entered, use the CHANGE  buttons to
move to the next one.
FREQUENCY Indicates the test frequency.
Indicates that the secondary function of a button will be used.
SWEEP Symbol not used in Model 6471
MANUAL Indicates MANUAL mode - the user has to stop the
measurement, otherwise the measurement keeps on running.
AUTO Indicates AUTO mode - measurement stops immediately after all
results are available.
NOISE
If blinking, indicates the measurement had a disturbance when
the measurement was started.
CONFIG Indicates that the blinking value of AUTO/MANUAL mode,
frequency, voltage or DC current direction can be changed.
MR Memory recall - indicates the displaying of stored results is
active
MEM
Indicates that there is recorded data in memory. When blinking,
it indicates that the results need to be saved by pressing the
MEM button.
REMOTE Indicates the instrument is remotely controlled by the RS-232/
USB interface.
SMOOTH Indicates SMOOTHing of the displayed measurement results.
Indicates that a clamp is (steady) or should be (ashing)
connected to ES.
Measured value (R, U, I).
Indicates that the measurement is running.
ALARM
Indicates the alarm is activated. An audible alarm will sound if
the value measured is above the limit dened in the SET-UP
mode.
Distances to be entered between earth electrode and
supplementary electrodes or between earth electrodes.

Ground Resistance Tester Model 6471 - User Manual 17
Clamp should be connected to H.
If this clamp symbol blinks, the instrument is refusing
measurement because the clamp is not connected correctly.
Symbolizes the soil resistivity value (Rho): W or S indicates that
Wenner or Schlumberger method is used for the measurement
(changed by the Hz/OPTIONS button).
2.5 BUTTON FUNCTIONS
START/STOP
Starts a measurement and compensates for lead resistance
(§ 5. 2.1).
Measurement stops automatically (AUTO) or is stopped by
pressing this button again (MANUAL).
Selects the second function highlighted in yellow under the
buttons.
Increases or decreases the value of the ashing parameter
displayed or selects the next parameter. Press the button for a
longer time to increase the change of value speed at a faster
rate.
Selects the parameter to be modied or moves the cursor to the
right.
MEM/MR MEM: Stores measurements to memory.
MR: Retrieves measurements from memory.
DISPLAY/
SMOOTH
DISPLAY: Displays all parameters of a measurement.
SMOOTH: Smooths the display of measurement providing a
more stable result.
Hz/OPTIONS/
DISTANCE
Hz/OPTIONS: Enables conguration of measurement functions.
DISTANCE: Available for soil resistivity and V potential
measurements. It allows the setting of values of distances used
for Rho (ρ) calculation.

18 Ground Resistance Tester Model 6471 - User Manual
3. SPECIFICATIONS
3.1 REFERENCE CONDITIONS
Inuencing Parameters Reference Values
Temperature 68 °F ± 5.5 °F (20 °C ± 3 °C)
Relative Humidity (45 to 55) % RH
Power Supply (9 to 11.2) V
Frequency Range of Input Signal (0 to 440) Hz
Capacitance Parallel to Input Resistance 0 uF
Electric Field <1 V/m
Magnetic Field < 40 A/m
3.2 ELECTRICAL
3.2.1 Frequency Measurements
Measuring method: Digital with a sampling frequency of 4028 Hz, low pass, FFT.
The frequency of the strongest spectral component is displayed.
Measuring rate: Display updates approx. 3 times per s.
Measurement Range (5 to 450) Hz
Resolution 1 Hz
Operating error ± 2 Hz
Min. input voltage 10 mV
Min. current through a clamp 0.5 mA
3.2.2 Voltage Measurements
Overvoltages up to 75 VRMS are displayed as >65 V. Permanent overvoltages
between (70 and 75) V at terminals H (Z) and E (X) can cause overheating of the
overvoltage protection varistor.
Voltages of more than 75 VRMS lead to error message 31 (excessive external
voltage) or 32 (voltage measurement overrange).
If terminals H (Z) and E (X) are put into contact with the line voltage, the
protection fuse will blow.

Ground Resistance Tester Model 6471 - User Manual 19
3.2.2.1 External Voltage Measurements
Measuring Method: Digital by sampling at 4028 Hz, low pass lter, FFT.
The frequency of the strongest spectral component is displayed.
Measuring Rate: Display updates approx. 3 times per s.
Signal Conversion: TRMS or sum of all harmonics (10 to 450) Hz during
selective earth measurements with a clamp.
Measured Range (0.00 to 9.99) V (10 to 65) V
Resolution 0.01 V 0.1 V
Intrinsic error ± (2 % + 1 ct)
Operating error ± (5 % + 1 ct)
Input impedance ZH-E, ZS-E, (ZS-ES) 1.2 MΩ
Operating frequency DC and (15 to 440) Hz
3.2.3 Current Measurements
3.2.3.1 External Current Measurements
Measuring Method: Digital by sampling at 4028 Hz, low pass lter, FFT.
Measuring Rate: Display updates approx. 3 times per s.
Signal Conversion: Sum of all harmonics (10 to 450) Hz
With Current Probe SR182
Measurement
Range
(0.00 to 9.99)
mA
(10.0 to 99.9)
mA
(100 to 999)
mA
(1.00 to 9.99)
A
(10 to 40)
A
Resolution 0.01 mA 0.1 mA 1 mA 0.01 A 0.1 A
Frequency range (16 to 49) Hz (50 to 99) Hz (100 to 400) Hz
Operating error from
(0.5 to 100) mA ± (10 % + 2 cts) ± (5 % + 2 cts) ± (3 % + 2 cts)
Operating error from
(0.1 to 40.0) A > 20 % ± (10 % + 2 cts) ± (5 % + 2 cts)
With Current Probe MN82
Measurement
Range
(0.00 to 9.99)
mA
(10.0 to 99.9)
mA
(100 to 999)
mA
(1.00 to 9.99)
A
(10 to 40)
A (1)
Resolution 0.01 mA 0.1 mA 1 mA 0.01 A 0.1 A
Frequency range (16 to 49) Hz (1) (50 to 99) Hz (1) (100 to 400) Hz
Operating error
from 0.5 to 100 mA ± (15 % + 2 cts) ± (7 % + 2 cts) ± (5 % + 2 cts)
Operating error
from 0.1 to 40.0 A > 20 % ± (15 % + 2 cts) ± (7 % + 2 cts)
(1): The Model 6471 cannot detect whether a current clamp SR182 or MN82 is connected. In the case of the
MN82 clamp, with currents >10 A and frequencies < 100 Hz the instrument will not display any warning
messages. It is the operator’s responsibility to observe the limits of use when using the MN82 clamp.

20 Ground Resistance Tester Model 6471 - User Manual
3.2.4 DC Resistance Measurements
Measuring method: Voltage/Current measurement (Standard EN 61557 part 4)
Nominal output voltage: 16 VDC (if resistance < 22 Ωthe output voltage is
reduced to 10 VDC)
Max output current: > 200 mADC for resistances < 20 Ω
Max overload (permanent): 50 VRMS (protection up to 250 V is guaranteed)
Max inductive load: 2 H
Max interfering voltage: 60 Vpeak > 10 Hz
Time for auto range selecting: approx. 5 s
Measuring time: 8 s with automatic polarity inversion
Measuring rate: 3 per s in manual mode
Lead compensation: Possible from (0 to 5) Ω
Alarm setting: > or <from (1 to 999) Ω(max 3 digits)
2-Pole mΩmeasurement
Measurement
Range
(0.12 to 9.99)
Ω
(10.0 to 99.9)
Ω
(100 to 999)
Ω
(1.00 to 9.99)
kΩ
(10.0 to 99.9)
kΩ
Resolution 0.01 Ω0.1 Ω1 Ω10 Ω100 Ω
Intrinsic error ± (2 % + 2 cts)
Operating error ± (5 % + 3 cts)
4-Pole mΩmeasurement
Measurement
Range
(0.020 to
9.999)
Ω
(10.00 to
99.99)
Ω
(100.0 to
999.9)
Ω
(1.000 to
9.999)
kΩ
(10.00 to
99.99)
kΩ
Resolution 0.001 Ω0.01 Ω0.1 Ω1 Ω10 Ω
Intrinsic error ± (2 % + 2 cts)
Operating error ± (5 % + 5 cts)