IDEAL 61-920 User manual
#61-920
Ground Clamp Resistance Meter
Instruction Manual
ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 1
99 Washington Street
Melrose, MA 02176
Fax 781-665-0780
TestEquipmentDepot.com
Contents
1. Safety warnings ..........................................................................................................1
2. Features ......................................................................................................................3
3. Specifications..............................................................................................................4
4. Instrument layout.........................................................................................................6
5. Measurement theory....................................................................................................7
6. Preparation for measurement ......................................................................................9
7. Measuring procedure ................................................................................................10
7-1 Normal measurement of current ........................................................................11
7-2 Measurement of balance leakage current............................................................11
7-3 Measurement of earth resistance. ......................................................................12
8. Other functions..........................................................................................................14
8-1 Auto power-off feature ........................................................................................14
8-2 Data hold feature ................................................................................................14
8-3 Continuity Buzzer function..................................................................................14
8-4 Backlight feature ................................................................................................14
8-5 Memory feature ..................................................................................................15
9. Battery replacement ..................................................................................................16
10. Service ......................................................................................................................17
11. Warranty....................................................................................................................18
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 2
1. Safety Warnings
This instrument has been designed, manufactured and tested according to IEC61010 Safety Requirements
for electronic measuring apparatus, and calibrated in accordance with practices using equipment that is cal-
ibrated to standards traceable to the National Institute for Standards and Technology (NIST). This instruction
manual contains warnings and safety procedures which must be observed to ensure safe operation of the
instrument and maintain it in a safe condition. These operating instructions must be read prior to using the
instrument.
WARNING
1. Use of personal protective gear, such as insulating gloves, boots, glasses, is recommended
even if the equipment is properly operated and grounded.
2. Safety is the responsibility of the operator.
3. Ensure meter is in proper working order before using. Visually inspect meter for damage.
4. Use extreme caution when using the instrument around energized electrical equipment.
5. Do not attempt to use the ground tester to twist or pry the ground electrode or ground wire away
from the equipment being grounded.
6. All metal objects or wires connected to the electrical system should be assumed to be lethal until
tested. Grounding systems are no exception.
7. Do not use without the battery and back case properly installed.
DANGER : is reserved for conditions and actions that are likely to cause
serious or fatal injury.
WARNING : is reserved for conditions and actions that can cause serious or
fatal injury.
CAUTION : is reserved for conditions and actions that can cause injury
or instrument damage.
Following symbols are used on the instrument. Attention should be paid to each symbol to
ensure your safety.
This symbol indicates that the user must refer to the explanations in the instruction manual.
This symbol indicates that the instrument is protected by double or reinforced insulation.
This symbol indicates that this instrument can clamp on bare conductors.
This symbol indicates AC.
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 3
DANGER
• Do not use the instrument on a circuit where electrical potential exceeds 300VAC.
• Do not use the instrument during an electrical storm.
• Do not use the instrument in the presence of flammable gas, dust or vapor.
• Wear insulated protective gear to avoid electrical shock.
• Use caution where the equipment under test has exposed metal parts.
• Never attempt to use the instrument if its surface or your hands are wet.
• Do not exceed the maximum allowable input of any measuring range.
• Do not use the instrument on a circuit over 30AAC. If “ “ is displayed on the LCD, stop
measurement immediately. Remove meter from conductor.
• Never open the battery cover during a measurement.
• When the transformer jaws are worn to the wear line (see the figure below), stop the use of the
instrument.
WARNING
• Do not use the instrument if any abnormal conditions, such as a broken cover or exposed metal parts
are present on the instrument.
• Do not install substitute parts or make any modification to the instrument. Return the instrument to:
IDEAL INDUSTRIES, INC.
Attn: Repair Department
1000 Park Avenue
Sycamore, IL 60178
• Do not try to replace the batteries if the surface of the instrument is wet.
• Always turn off the instrument before opening the battery cover for battery replacement.
• Always be sure to keep your fingers and hands behind the Safety barrier.
(see figure below) Otherwise, user may be exposed to the danger of electrical shock.
CAUTION
• Press the Function button and confirm the appropriate function is selected before starting a
measurement.
• Do not expose the instrument to the direct sun, high temperatures and humidity or dew.
• Press the Power button and turn off the instrument after use. When the instrument is not in use for
a long period of time, place it in a storage after removing the batteries.
• Use a damp cloth with mild detergent for cleaning the instrument. Do not use abrasives or solvents.
• Do not drop. Precisely adjusted transformer jaws will be damaged.
• Keep jaw tips clear of debris.
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 4
2. Features
The 61-920 is a digital clamp-on ground resistance tester. The instrument can measure the ground resist-
ance by simply clamping around the ground conductor, ground rod or equipment ground conductor.
The 61-920 also measures leakage AC current up to 30AAC.
• Wide measuring range (Auto-ranging)
Ground resistance Max. 1200ΩMin. resolution 0.01Ω
AC current Max. 30A Min. resolution 0.1mA
• Noise check function senses current on the ground electrode or ground wire and displays NOISE on
the LCD display.
• True RMS feature accurately measures AC current even with distorted waveforms due to harmonics.
• Auto power-off feature powers the meter down automatically after 10 minutes of non-use to conserve
battery power.
• Data hold feature is used to capture and hold a reading in the LCD display.
• Continuity buzzer function provides an audible warning to the user when the measurement result is
10Ωor less.
• Backlight feature illuminates the display for working in dimly lit areas.
• Memory save feature records and displays the measurement result.
• Complies with IEC61010-1: 2001 (CAT.IV 300V Pollution degree 2), IEC61010-2-032: 2002 safety
standards.
• This instrument is protected by double or reinforced insulation .
Page 5
ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 5
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
Page 6
3. Specifications
• Measuring range and accuracy
Function Range Resolution Measuring range Accuracy
Earth 20Ω0.01Ω0.00 ~20.99Ω±1.5%±0.05Ω
resistance 200Ω0.1Ω16.0 ~ 99.9Ω±2%±0.5Ω
(Auto-ranging) 100.0 ~ 209.9Ω±3%±2Ω
1Ω160 ~ 399Ω±5%±5Ω
1200Ω400 ~ 599Ω±10%±10Ω
10Ω600 ~ 1260Ω—
AC current (ACA) 100mA 0.1mA 0.0 ~ 104.9mA ±2%±0.7mA
(sine wave) 1000mA 1mA 80 ~ 1049mA
(50Hz/60Hz) 10A 0.01A 0.80 ~ 10.49mA ±2%
(Auto ranging) 30A 0.1A 8.0 ~ 31.5AmA
* Crest factor <2.5 Accuracy at sine wave +1% (50Hz/60Hz, peak value shall not exceed 60A)
* In the following cases, zero will be displayed on the LCD.
At 20Ωrange of Earth resistance function: 0.04Ωor less
* Auto ranging shifts to upper range when the input exceeds 105% of the selected range, and shifts to the lower range when the input
falls under 80% of the lower range.
• Operating system Earth resistance function: Constant voltage injection, Current detection,
(Frequency: Approx. 2400Hz)
Dual Integration
AC current function: Successive Approximation (True-RMS)
• Display Liquid crystal display with a maximum count of 2099
• Over-range indication "OL" is displayed when input exceeds the upper limit of a measuring range
• Response time Earth resistance function: Approx. 7 seconds
AC current function: Approx. 2 seconds
• Sample rate Approx. once per second
• Location for use Altitude 2000m or less, Indoor/ outdoor use
• IP protection degree IP40
• Temperature & 75°F±5%/Relative humidity 85% or less
humidity range (no condensation)
(guaranteed accuracy)
• Operating temperature 14°F ~ 104°F/Relative humidity 85% or less
& humidity range (no condensation)
• Storage temperature -4°F ~ 140°F/Relative humidity 85% or less
& humidity range (without batteries, no condensation)
• Power source (4) batteries AA
• Current consumption Approx. 50mA (max. 100mA)
• Measurement time Approx. 12 hours (when manganese battery is used),
Approx. 24 hours (when alkaline battery is used)
• Auto power-off Turns power off after 10 minutes of non-use.
ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 6
• Applicable standards IEC61010-1: 2001 (CAT. IV 300V Pollution degree 2)
IEC61010-2-032: 2002
IEC61326: 2000 (EMC standard)
• Electrostatic discharge Performance criteria B
immunity
• Withstand voltage AC5320Vrms/ 5 seconds
Between the Transformer jaws fitted parts and Case enclosure (except for jaws)
• Insulation resistance 50MΩor more at 1000V
Between the Transformer jaws fitted parts and Case enclosure (except for jaws)
• Conductor size Approx. 1.25" in diameter max.
• Dimension 9.7"(L) x 4.7"(W) x 2.1"(D)
• Weight Approx. 1.7 lbs (including batteries)
• Accessories Battery AA : 4 pcs.
Instruction manual : 1 pc.
Resistor for operation check : 1 pc.
Hard case : 1 pc.
<Supplemental remarks>
Effective value (RMS)
Most alternating currents and voltages are expressed in effective values, which are also referred to as
RMS (Root-Mean-Square) values. The effective value is the square root of the average of square of
alternating current or voltage values. Many clamp meters using a conventional rectifying circuit have
"RMS" scales for AC measurement. The scales are calibrated in terms of the effective value of a sine
wave through the clamp meter responding to the average value. The calibration is done with a conver-
sion factor of 1.111 for sine wave, which is found by dividing the effective value by the average value.
These instruments are therefore in error if the input voltage or current has some other shape than a
sine wave.
CF (Crest Factor) is found by dividing the peak value by the effective value.
Examples:
Sine wave: CF=1.414 Square wave with a 1: 9 duty ratio: CF=3
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 7
Page 8
2
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1
4. Instrument Layout
• Feature callouts
Transformer jaw
Lever
Backlight button
Switches on/off the backlight
Function button
Switches ACA/Earth resistance function
Memory mode button
Records the measured value with
a data number
Data hold button
Holds the indicated value.
Release the held value
Power button
Turns the meter on/off
Display unit (LCD)
Cursor button (UP)
Selects data number to save the
measured value or to view the
measured data in memory
Cursor button (DOWN)
Selects data number to save the
measured value or to view the
measured data in memory.
Save button
Saves the measured value.
Data number
1 to 100
UnitMeasured value
• Marks to be displayed on the LCD
Displayed when saving the measured value or
when instrument is in memory mode
Displayed when batteries are exhausted
Displayed in Earth resistance function when
Transformer jaws are not properly closed
Displayed in Earth resistance function with cur-
rent or noise which affects the measured value
Displayed when data hold functions activated
Displayed when ACA function is selected
Displayed when instrument is in continuity
mode at Earth resistance function
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 8
5. Measurement Theory
This instrument can measure the earth resistance to earth in multi-earthed system. Let's regard earth resist-
ance under test as Rx, and the other earth resistances as R1, R2, …Rn.
Of these earth resistances, R1, R2, …Rn can be considered connected in parallel and can be regarded as a
combined resistance Rs. The Rs can be regarded small enough against Rx since combined resistance con-
sists of several resistances. Following is an equivalent circuit diagram of this scenario.
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ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 9
Page 10
By applying the Voltage (V) to the circuit from the transformer jaw (CT1), current I is flowing in relation to
the earth resistance. R can be determined by calculation after measuring the current with the other trans-
former jaw (CT2). In this case, R displayed in this meter can be regarded as Rx because Rs can be regarded
small enough against Rx.
CAUTION
This meter cannot support the measurement for the locations with the following earth systems.
• Single-earth that is not connected to other earths (Lightning rod, etc.)
• Earth on which a current over 2AAC is measured.
• Earth with earth resistance over 1200Ω.
ND 5417-1 61-920 Ins 9/26/06 8:49 AM Page 10
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
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