AEMC 3711 User manual
Clamp-On
Ground Resistance Tester
Models 3711 and 3731
USER MANUAL
A
Ω
ON
OFF
MEM AL A
Ω
ON
OFF
®
®
Statement of Compliance
Chauvin Arnoux®, Inc. d.b.a. AEMC®Instruments
certifies 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 its published specifications.
An NIST traceable certificate 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.
Serial #:
Catalog #:
2117.60/2117.61
Model #:
3711/3731
Please fill in the appropriate date as indicated:
Date Received:
Date Calibration Due:
Chauvin Arnoux®, Inc.
d.b.a AEMC®Instruments
www.aemc.com
Limited Warranty
The Models 3711 and 3731 are warranted to the owner for a period of
one year from the date of original purchase against defects in
manufacture. This limited warranty is given by AEMC®Instruments, not
by the distributor from whom it was purchased. This warranty is void if
the unit has been tampered with, abused or if the defect is related to
service not performed by AEMC®Instruments.
For full and detailed warranty coverage, please read the Warranty
Coverage Information, which is attached to the Warranty
Registration Card (if enclosed) or is available at www.aemc.com.
Please keep the Warranty Coverage Information with your records.
What AEMC®Instruments will do:
If a malfunction occurs within the one-year period, you may return the
instrument to us for repair, provided we have your warranty registration
information on file or a proof of purchase. AEMC®Instruments will, at its
option, repair or replace the faulty material.
YOU CAN NOW REGISTER ONLINE AT:
www.aemc.com
Warranty Repairs
What you must do to return an Instrument for Warranty Repair:
First, request a Customer Service Authorization Number (CSA#) by
phone or by fax from our Service Department (see address below), then
return the instrument along with the signed CSA Form. Please write the
CSA# on the outside of the shipping container. Return the instrument,
postage or shipment pre-paid to:
Chauvin Arnoux®, Inc. d.b.a. AEMC®Instruments
15 Faraday Drive • Dover, NH 03820 USA
Tel: (800) 945-2362 (Ext. 360)
(603) 749-6434 (Ext. 360)
Fax: (603) 742-2346 or (603) 749-6309
Caution: To protect yourself against in-transit loss, we recommend you
insure your returned material.
NOTE: All customers must obtain a CSA# before returning any
instrument.
Table of Contents
Warning.....................................................................................................4
International Electrical Symbols................................................................4
Definition of Measurement Categories......................................................5
Receiving Your Shipment..........................................................................5
Packaging..................................................................................................5
Accessories...............................................................................................5
Important Information - Proper Operation.................................................5
Description ................................................................................................6
Product Construction.............................................................................6
Jaw Design............................................................................................7
Body Design..........................................................................................7
Electrical Specifications ............................................................................8
Ground Resistance................................................................................8
Ground or Leakage Current...................................................................8
Mechanical Specifications.........................................................................8
Safety Specifications.................................................................................9
Model 3711 Controls...............................................................................10
Model 3731 Controls...............................................................................11
Digital Display Features..........................................................................12
Additional Features of the Model 3731................................................13
Function Controls....................................................................................14
On/Off..................................................................................................14
Auto-Off ...............................................................................................15
Hold .....................................................................................................15
Beeper Disable....................................................................................15
Resistance...........................................................................................15
Resistance...........................................................................................16
Current.................................................................................................17
Alarm ...................................................................................................18
Programming the Alarm Setpoint........................................................18
Changing the Alarm Trigger ................................................................19
Memory................................................................................................19
Memory................................................................................................20
Memory Recall.....................................................................................20
Clear Memory......................................................................................20
Function Access Summary .....................................................................21
Programming Summary..........................................................................21
Principle of Operation..............................................................................22
Field Applications....................................................................................24
Pole Ground Rods...............................................................................24
Service Entrance or Meter...................................................................25
Pad Mounted Transformer...................................................................25
Pad Mounted Transformer...................................................................26
Transmission Towers ..........................................................................27
Central Office Locations......................................................................27
Service Panel ......................................................................................28
Phone Pedestal...................................................................................29
Above Telephone Space.....................................................................31
General Measurement Notes ..............................................................31
Operating Reference Card......................................................................32
Field Test Loop........................................................................................32
Commonly Asked Questions for..............................................................33
Clamp-on Ground Resistance Measurements........................................33
Maintenance............................................................................................34
Battery Replacement Procedure.............................................................35
Troubleshooting ......................................................................................35
Repair and Calibration ............................................................................36
Technical and Sales Assistance .............................................................36
Ground Resistance Tester Models 3711 and 3731
- 4 -
Warning
These safety warnings are provided to ensure the safety of
personnel and proper operation of the instrument.
•The instrument must not be operated beyond its specified
operating range.
•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.
•Use extreme caution when using the instrument around
energized electrical equipment.
•Never attempt to use the instrument to twist or pry the ground
electrode or ground wire away from the equipment being
grounded.
•Open and close the clamp-on jaws slowly ensuring proper
alignment.
•AEMC®Instruments considers the use of rubber gloves to be
an excellent safety practice even if the equipment is properly
operated and correctly grounded.
International Electrical Symbols
This symbol signifies that the instrument is protected by double
or reinforced insulation. Use only specified replacement parts
when servicing the instrument.
This symbol signifies CAUTION! and requests that the user refer
to the user manual before using the instrument.
Risk of electric shock. The voltage at the parts marked with this
symbol may be dangerous.
This is a type A current sensor. This symbol signifies that
application around and removal from HAZARDOUS LIVE
conductors is permitted.
Ground Resistance Tester Models 3711 and 3731
- 5 -
Definition of Measurement Categories
Cat. I: For measurements on circuits not directly connected to the AC
supply wall outlet such as protected secondaries, signal level,
and limited energy circuits.
Cat. II: For measurements performed on circuits directly connected to
the electrical distribution system. Examples are measurements
on household appliances or portable tools.
Cat. III: For measurements performed in the building installation at the
distribution level such as on hardwired equipment in fixed
installation and circuit breakers.
Cat. IV: For measurements performed at the primary electrical supply
(<1000V) such as on primary overcurrent protection devices,
ripple control units, or meters
Receiving Your Shipment
Upon receiving your shipment, be sure that the contents are consistent
with the packing list. Notify your distributor of any missing items. If the
equipment appears to be damaged, file 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.
Packaging
The Model 3711 (Cat. #2117.60) and Model 3731 (Cat. #2117.61) are
shipped with a hard carrying case, one 9V battery (not installed), a user
manual with warranty registration and a field test loop. The manual,
warranty card, and test loop are located behind the “egg crate” foam on
the inside of the carrying case cover.
Accessories
Multiple Calibration Loop......................................................Cat. #1223.01
Important Information - Proper Operation
The proper operation and measurement accuracy depends on the proper
jaw closing. For any measurement make sure that the jaw mating
surfaces are clean and that no foreign matter obstructs their closing.
Ground Resistance Tester Models 3711 and 3731
- 6 -
Description
The Ground Resistance Tester, Models 3711 and 3731, measure ground
rod and small grid resistance through any season, without the use of
auxiliary ground rods. Clamp-on ground resistance testers are used in
multi-grounded systems without disconnecting the ground under test.
The Models 3711 and 3731 simply clamp around the ground conductor
or rod and measure the resistance to ground. By performing
measurements on intact ground systems, the user also verifies the
quality of the grounding connections and bonds. Resistance and
continuity of grounding loops around pads and buildings may also be
measured.
Both models include a current measurement function. The probe’s high
sensitivity enables measurement of leakage current flowing to ground or
circulating in ground loops down to 1mA and neutral currents to 30Arms.
This feature provides additional information which is becoming vital as
distribution ground networks carry higher levels of noise and harmonics
which affect power quality.
Both models offer battery life information at power-up and Auto-Off for
power management. Additional features are also displayed on the large
LCD to ensure precise measurements. The Buzzer and Auto-Off features
may be disabled from the push-buttons at any time.
The Model 3731 offers an Alarm function and a Memory (logging)
function. In the Alarm mode, the probe will audibly and visually indicate if
the reading is beyond an input set point. The user may also have the
Alarm initiated above or below the set point. This Alarm feature permits
quick field checks where only “pass” or “fail” readings will suffice.
The Memory function logs up to 99 measurements (Ohms or Amperes).
This enables the user to conduct field surveys, and to retrieve and
analyze the readings at a later time. The alarm settings and stored
memory information are saved when the ground tester is turned off.
Product Construction
The Models 3711 and 3731 body cases are built of Lexan®for rugged
use. The probe heads are encapsulated in a double-walled Lexan®shell
(or equivalent polycarbonate) for extra strength and are reinforced at the
body interfaces for enhanced field reliability. Overall construction and
mechanical design ratings such as drop test, shock and vibration,
weatherproofing against water projections, meet or exceed IEC
(International Electrotechnical Commission) standards. The products
have also been designed to meet EN 61010.
Ground Resistance Tester Models 3711 and 3731
- 7 -
Jaw Design
The probe head, or jaw, is a key component in the measurement and
overall product performance. Considerable research and development
were dedicated to ensuring its performance, reliability and versatility.
The large jaw has an inner opening diameter of 1.25" (32mm) permitting
use on tight ground conductors on poles and in manholes. The large
opening accommodates not only ground rods, but larger ground
conductors (up to 1000 kcmil) typically found in telecommunication or
railroad applications.
The inner jaw is composed of two independent and individually shielded
magnetic cores permitting the injection of a test signal and accurate
return signal measurement without noise interference or cross talk
common to separate probe instruments.
Thorough mechanical design, including small winglets, ensures repetitive
jaw alignment for accuracy and prevents undesirable insertions into the
jaw spring assembly.
Body Design
The ergonomic body design permits one-handed operation. The guard
provides additional strength, and prevents the hand from slipping or
coming into contact with conductors under test. The Lexan®(or
equivalent polycarbonate) body construction provides strength. The LCD
lens cover may be easily replaced if scratched. The sealed push-buttons
directly access all test functions and are easily operated even with
gloved hands.
Lexan®is a registered trademark of General Electric Corporation.
Ground Resistance Tester Models 3711 and 3731
- 8 -
Electrical Specifications
Ground Resistance
Measurement Range Range Resolution Accuracy*
0.1 to 1.00Ω0.01Ω± (2% R ± 0.02Ω)
1.0 to 50.0Ω0.1Ω± (1.5% R ± 0.1Ω)
50.0 to 100.0Ω0.5Ω± (2.0% R ± 0.5Ω)
100 to 200Ω1Ω± (3.0% R ± 1Ω)
200 to 400Ω5Ω± (6.0% R ± 5Ω)
400 to 600Ω10Ω± (10% R ± 10Ω)
Autoranging
0.01Ωto 1200Ω
600 to 1200Ω50ΩApprox. 25% ± 50Ω
Ground or Leakage Current
Measurement Range Range Resolution Accuracy*
1 to 299mA 1mA ± (2.5% R + 2mA)
0.300A to 2.999A 0.001A ± (2.5% R + 2mA)
Autoranging
1mA to 30.00Arms 3.00A to 29.99A 0.01A ± (2.5% R + 20mA)
R = Reading
* Reference conditions: 23°C ± 3K, 50% RH ± 10%, battery at 8V ± 0.2V, external magnetic
field < 40A/m, external electrical field < 1V/m, conductor centered, loop resistance
noninductive. Accuracy % of Reading, Frequency: 50/60Hz.
Resistance Measurement Frequency: 2403Hz
Voltage Generated into the Loop: Approx. 60mVrms
Alarm Range (Model 3731 Only): 0 to 199Ω
Resistance Overload: OL displayed above 1200Ω
Current Measurement Frequency: 47 to 800Hz
Influence of Frequency: Add 7.5% to the reference specification
Current Overload: OL displayed above 29.99Arms
Mechanical Specifications
Dimensions: 9.25 x 3.94 x 2.17" (235 x 100 x 55mm)
Weight: 2.2lbs. (1kg)
Ground Resistance Tester Models 3711 and 3731
- 9 -
Case Material: Lexan®920A (UL94V2) or equivalent
Jaw Cover Material:
Lexan®with 10% fiberglass charge (UL94V0) or equivalent
LCD Cover Material: Clear Lexan®(UL94V1) or equivalent
Color: Gray body, red jaws
Jaw Window Diameter: 1.25” (32mm)
Jaw Opening: 1.38” (35mm)
Operating Temperature: 14° to 131°F (-10° to 55°C)
Operating Humidity:
10 to 90% RH @ 14° to 104°F (-10° to 40°C), 75% RH @ 131°F (55°C)
Storage Temperature: -22° to 158°F (-30° to 70°C)
Altitude: Operational - 2000m; Storage - 12000m
Power Supply: 9V Alkaline (IEC 6LF22 or NEDA 1604A)
Battery Life: Typical: 8 hours or approx. 1000 measurements of 30 s
LCD: 3-3/4 digit, 1.73 x 1.10” (44 x 28mm)
US Design Patent: No. 362,639
Safety Specifications
EN 61010-1 (Class 2), Double Insulation
Working Voltage: 150V, Cat. III - Pollution Degree 2
300V, Cat. II - Pollution Degree 2
Environmental: IP30 (Protection Index) EN 60529 Ed. 92
IK04, EN 50102 Ed. 95
Vibration Test: IEC 68-2-6
Shock Test: IEC 68-2-27
Drop Test (1m): IEC 68-2-32
Max A Overload: 100A continuous, 200A (< 5s) 50/60Hz
OL displayed above 29.99Arms
Electromagnetic Compatibility:
EN 61326-1+A1 (industrial environment)
EM Field: IEC 61000-4-3, criteria B
Ground Resistance Tester Models 3711 and 3731
- 10 -
Model 3711 Controls
A
Ω
ON
OFF
1. Head Assembly: Consists of
two individually shielded
magnetic cores.
2. Hold: Freezes last measured
value on the display.
3. Display: 3000 count LCD,
function indicators.
4. ON/OFF: Power ON or OFF,
activates display self-test at
power-up.
5. Ω: Resistance measurement.
6. A: Current measurement.
7. Lever: Opens or closes jaws.
Figure 1
Ground Resistance Tester Models 3711 and 3731
- 11 -
Model 3731 Controls
1. Head Assembly: Consists of two
individually shielded magnetic
cores.
2. Hold: Freezes last measured
value on the display.
3. Display: 3000 count LCD,
function indicators.
4. ON/OFF: Power ON or OFF,
activates display self test at
power-up.
5. Ω: Resistance Measurement
Increment the Alarm setpoint,
increment Memory position in
program mode.
6. A: Current Measurement
Decrement the Alarm setpoint,
decrement the Memory in
program mode.
7. AL: Activates/deactivates the Alarm function, access the value of the
Alarm setpoint in program mode.
8. MEM: Stores the reading into memory, reads Memory Recall (MR)
values and clears the memory in recall mode.
9. Lever: Opens or closes jaws.
HOLD
+
–
m
A
R1
HOLD
MEM
MR
NOISE
MEM AL A Ω
ON
OFF
Model 3731
GROUND TESTER
®
INSTRUMENTS
1
2
3
48
5
6
7
9
Ground Resistance Tester Models 3711 and 3731
- 12 -
Digital Display Features
+
m
A
R.1
HOLD
MEM
MR
NOISE
Displayed when the beeper is active. To turn the beeper On/Off,
push ON & Ωtogether at power-up. The beeper is active when
displayed.
Displayed when the HOLD function is activated. This function
locks the present displayed value. During HOLD: A, Ω, and
Alarm functions are deactivated. The Memory function may still
be used.
Indicates that the jaws of the instrument are not properly closed.
The Open Jaw indication is present only in the ΩMode. Check
for foreign matter in the jaw mating surface.
In the Ωfunction, this symbol indicates the presence of
excessive stray noise in the ground electrode under test. This
symbol will be present if noise signals reach an amplitude of
approx. 5A or 50V. Resistance measurement values are no
longer valid. The beeper is also activated.
Displayed when measured resistance is below 0.1Ω. This may
indicate that grounding electrode you are clamped onto is
continuous with itself (the instrument is measuring a metallic
loop and not the ground electrode resistance). In this situation,
electrode resistance measurements may not be valid. The main
display can measure between 0.7 to 0.07Ω, but without any
specified accuracy.
Current measurement mode.
Ground resistance measurement mode.
Figure 3
HOLD
NOISE
mA, A
R.1
Ground Resistance Tester Models 3711 and 3731
- 13 -
Indicates the Auto-Off feature is deactivated and the instrument
stays on permanently (until turned off by the user). With no
symbol displayed, after 5 minutes of non-use the instrument will
automatically shut itself off. The Auto-Off feature is turned
On/Off by pressing Hold at power-up.
Display flashes this symbol (1/second) during a low battery
condition. Measurements are still possible. When this symbol is
displayed continuously, measurements are no longer possible.
Battery replacement is necessary.
Indicates the approximate percentage of useful battery life
remaining (0-100%). This function is displayed only upon initial
power-up when the ON push-button is held down for more than
2 seconds.
The overload symbol will illuminate when the measurement
reading is beyond the limits of the instrument:
Resistance > 1200Ω
Current > 30.00A rms
The beeper is activated in current overload.
Additional Features of the Model 3731
Indicates that an alarm set point is set in memory. Alarm set
points may be set from 1 to 199Ω. Arrows indicate whether the
measured value is above or below alarm setpoint.
Memory function is activated. Ninety-nine (99) separate values
may be logged for either resistance (Ω), current (A) or a
combination thereof. At the 99th value, display number will blink
indicating that memory is full.
Memory recall register. Displays the numbered value being
recalled from memory (1-99).
Note: Models 3711 and 3731 share the same LCD and display all
segments at power-up. Functions not available on the 3711 are
displayed at power-up.
MEM
MR
Ground Resistance Tester Models 3711 and 3731
- 14 -
Function Controls
Model 3711 and 3731 share common functions (On/Off, A,
Ω
, Auto-off,
Buzzer disable, Hold). Even though the Model 3711 is shown in the
examples for these functions, the controls will respond identically for the
Model 3731.
On/Off
The ON/OFF push-button, when pushed actuates power on or power off
with an audible control tone. Upon initial power-up, the instrument will be
in the Ohms function (Ω) and will go to OL until clamped on. When the
ON push-button is pushed and held down, after three seconds the
instrument will beep and provide a self test featuring a full function
display (Fig. 4) followed by status indications for:
a. Status of remaining battery life
(battery symbol blinks, 0-100%) (Fig. 5)
b. Number of stored values in memory
(MEM blinks, 0-99) (Model 3731 only)
Release the ON/OFF push-button to initialize the instrument.
A
Ω
ON
OFF
A
Ω
ON
OFF
Figure 4 Figure 5
Ground Resistance Tester Models 3711 and 3731
- 15 -
Auto-Off
The instrument will shut off automatically after five minutes of non-use.
The instrument will issue a short beep 15 seconds prior to shutting down
and the LCD flashes once per second. The
Auto-Off may be disabled by turning on the
meter while holding down the HOLD push-
button. The indicator will appear on the
display to indicate the Auto-Off feature has
been disabled. (Fig. 6).
Hold
The HOLD push-button freezes the last
measured value onto the display. When the
HOLD function is enabled,
HOLD
is
displayed on the LCD. (Fig. 7)
When the HOLD function is enabled, other control
functions are disabled (except the memory
function).
To exit HOLD, press the HOLD push-button and
normal operation is resumed.
Note: When HOLD is pressed during power-up,
the auto-off feature is disabled and is
displayed on the LCD. See Auto-Off.
Beeper Disable
To disable the beeper, press the ON and Ω
together at power-up. The indicator will
disappear from the LCD. (Fig. 8).
This setting is saved indefinitely. To reset the
beeper, press the ON and Ωtogether at power
up.
Figure 6
A
Ω
ON
OFF
A
Ω
ON
OFF
Figure 7
A
Ω
ON
OFF
Figure 8
Ground Resistance Tester Models 3711 and 3731
- 16 -
Resistance
The Ωfunction provides resistance measurements from 0.1 to 1200Ωin
seven autoranges. (Fig. 9).
Range Resolution
0.07 to 1Ω0.01Ω
1.0 to 50.0Ω0.1Ω
50 to 100Ω0.5Ω
100 to 200Ω1Ω
200 to 400Ω5Ω
400 to 600Ω10Ω
600 to 1200Ω50Ω
Upon initial power-on, the Ωfunction is chosen by default.
The Models 3711 and 3731 will track down to
0.07Ωand indicate
R.1
below 0.1Ω(Fig. 10).
Accuracy is not defined below 0.1Ω.
Measurements below 0.1Ωtypically (or even
1Ω) indicate the ground tester is clamped onto
a closed loop and that the signal is not flowing
through the ground under test.
If the resistance readings are above 1200Ω, OL
will be displayed on the LCD (Fig. 11). This may
indicate high ground resistance but may also be
caused by a disconnected or poorly bonded
ground.
Figure 9
Figure 10
Figure 11
AON
OFF
A
Ω
ON
OFF
AΩ
ON
OFF
Ground Resistance Tester Models 3711 and 3731
- 17 -
Current
Press A to enter the current function. True RMS current measurements
are possible up to 30.00A (Fig. 12).
Above 30Arms, OL will be displayed and the test must be discontinued.
The beeper is also activated during OL.
Range Resolution
1 to 299mA 1mA
0.300 to 2.999A 0.001A (1mA)
3.00A to 29.99A 0.01A (10mA)
A
Ω
ON
OFF
Figure 12
Ground Resistance Tester Models 3711 and 3731
- 18 -
Alarm
Turn the Alarm on/off by pressing the AL
button. The alarm feature provides a
continuous audible warning (when beeper is
active) and visual indications when a
setpoint has been reached (Fig. 13, 14) (e.g.
alarm indication when ground electrode
resistance is above the NEC limit of 25Ω.) If
the alarm is not triggered, only will be
displayed indicating that the alarm is active.
Programming the Alarm Setpoint
To program the alarm setpoint, push ON and AL together at power-up.
The alarm setpoint value will blink. To program the proper setpoint value
(1 to 199Ω), use the cursor arrows ( down, up).
When the setpoint is reached, turn the
instrument off. This will put the setpoint into
memory. Turn the instrument back on (you
may need to press AL to activate the alarm
feature).
Note: The alarm setpoint is preset at 25Ω.
The alarm will be triggered when the
setpoint is exceeded.
The user has the option of having the alarm
triggered when a reading is below the
programmed setpoint. This is accomplished
with an internal switch and outlined in the
following section.
Figure 13
Figure 14
MEM AL A
Ω
ON
OFF
MEM AL A
Ω
ON
OFF
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