Tenma 72-8720 User manual

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Model: 72-8720
Digital Bench Multimeter

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Please read these instructions carefully before use and retain for future
reference.
• This meter is designed to meet IEC61010-1, 61010-2-032, and 61010-2-033 in
Pollution Degree 2, Measurement Category (CAT I 1000V, CAT II 600V, CAT III
300V) and double Insulation.
• When using electrical appliances basic safety precautions should always be
followed.
• Please operate according to this manual, otherwise the protection provided by the
device will be impaired or fail.
• There are no user-serviceable parts in this product. Refer servicing to qualied
personnel.
• Use only the test leads supplied or the protection may be impaired.
• Check the test leads, probe and case insulation condition before using. If you nd
any breakage, damage or abnormality, or you consider the device is broken, stop
using the device immediately.
• When using the test probes, keep your ngers behind the nger protection rings.
• Ensure all inputs are less than the range selected otherwise it may cause electrical
shock or meter damage.
• Take caution when voltages are above 60V DC and 30V AC rms.
• Do not use the meter with the battery or fuse covers removed.
• Do not adjust the range selector during measurement.
• Replace the batteries as soon as the low battery indicator appears on the display.
• Remove dead batteries from the meter or if it is not going to be used for a long
time.
• Never mix old and new batteries together, or different types of batteries.
• Never dispose of batteries in a re, or attempt to recharge ordinary batteries.
• Before replacing the battery, turn off the meter and disconnect all the test probes
• To prolong battery life turn off the meter after use.
ELECTRICAL SYMBOLS GUIDE
WHAT’S INCLUDED
• Bench type digital multimeter.
• Installation guide and computer interface software (CD-ROM).
• Operating manual.
• Power cord.
• Alligator clip.
• Multi purpose socket.
• Temperature probe.
• Test leads (1 pair).
• RS232 interface cable.
• USB interface cable.
IMPORTANT SAFETY INFORMATION
AC or DC Ground Double insulated
Continuity test
Low batteryWarning
Capacitance test
Diode test Fuse
}Stored in compartment in the back of the unit.

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FUNCTIONS
Function buttons Operation performed
SELECT SELECT: used to select any rotary switch alternate function
LIGHT LIGHT: under battery power turns backlight on
RANGE Exit AUTO and enter MANUAL ranging. In MANUAL select next
input range. Press EXIT to return to AUTO (default)
STORE Stores the current measurement value. Press EXIT to return
RECALL Recall the stored value. Press EXIT to return
SETUP Access setup selections. Display ‘SET’ is ashing. Each press
moves to the next selection.
SEND Press to output data, AUTO mode off. Press EXIT to quit
In SETUP press to select OFF at selection of HIGH and LOW
MAXMIN
Displays max/min and current reading. Press exit to quit
In SETUP each press select next digit
In RECALL press to enable SEND feature
In STORE press to switch between clearing or start storing
reading from current index number
REL
Enter RELATIVE mode. Upper right secondary display shows
present value. Lower right secondary display shows stored
value. Primary display shows present measurement minus
stored value. Press EXIT to quit mode.
Range Selector
Positions
Rotary Switch Function Blue SELECT Function
V
DC voltage measurement None
~
V
AC voltage measurement None
Hz Duty
mV
DC millivolt measurement Frequency measurements
Duty Cycle measurement
Resistance measurement Diode test
Continuity test
Capacitance test None
ºC ºF Centigrade temp measurement Fahrenheit temp measurement
μA
AC or DC current
measurement (40ma, 400ma)
Switch between AC or DC
mA %
AC or DC current
measurement (40ma, 400ma)
Switch between AC or DC
4-20mA loop as % reading
AAC or DC current
measurement (10A)
Switch between AC or DC
Ω

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Function buttons Operation performed
REL
In SETUP each press decrements an option
In RECALL each press goes back to previous reading
In STORE each press decreases a second on the storing
interval. Press EXIT to exit.
HOLD HOLD freezes the displayed value. Press EXIT to release.
PEAK Press to access Peak Hold feature. Primary display shows peak
hold reading. Press EXIT to quit.
EXIT Press to exit certain button functions.
AC/DC In AC measurement mode press to display AC+DC True RMS
value and AC+DC.
OPERATING PARAMETERS
FRONT PANEL LAYOUT
• Ambient temperature : 0ºC ~ 40ºC.
• Relative humidity : ≤75% @ 0ºC ~ 30ºC, ≤50% @ 31ºC ~ 40ºC
• Maximum operating altitude 2000m
• Maximum Display : Digital: 5999
• Measurement Speed : Updates 2-3 times/second
• Polarity display : Automatic
• Turn the Range Selector to power the meter on and select a function. The display
initially shows a standard setup for that function.
• Use the blue SELECT button to choose an alternate function for the chosen
setting.
• Changing the main setting does not carry over the alternative function setting.
LCD Display
Function Buttons
Range Selector
Select Button
Input Terminals AC/AC+DC Button
SELECT RANGE STORE RECALL SETUP

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Function Primary Display Lower right
Secondary Display
Upper right Secondary
Display
DCV Tested DC Voltage value No Display Full range: 4,40,400,1000
ACV Tested AC Voltage value
Tested frequency
value: 40kHz ~
250kHz
Full range: 4,40,400,750
DCmV Tested DCmV value No display Full range: 400
Ω Tested resistance value No display Full range: 400, 4, 40, 400,
4, 40
Tested resistance value No display Full range value: 400
Tested resistance value No display Full range: 4
Hz Tested frequency value No display Full range: 40, 400, 4, 40,
400, 4, 40, 400
Tested capacitance value No display Full range: 40, 400, 4, 40,
400, 4, 40
ºC Tested ºC value No display 1000
ºF Tested ºF value No display 1832
DC μA Tested DC μA value N/A Full range: 400, 4000
AC μA Tested AC μA value
Tested frequency
value 40kHz ~ 100kHz Full range: 400, 4000
DCmA Tested DCmA value No display Full range: 40, 400
ACmA Tested ACmA value Tested frequency
value 40kHz ~ 100kHz Full range: 400, 4000
DCA Tested DC current value No display Full range: 10
ACA Tested AC current value Tested frequency
value 40kHz ~ 100kHz Full range: 10
STORE Current measurement
reading
Value of the
corresponding index
number
Index number increase one.
Index number:
no.0001~9999
RECALL The recalled value The total number of
stored value
Index number:
no.0001~9999
Max/min Current measurement
reading
Minimum reading
value Maximum reading value
REL Present measurement
value minus stored value The stored value Present measurement value

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Symbol Meaning
MAX Maximum reading displayed
MIN Minimum reading displayed
No The sequence of reading
ºC, ºF Degrees celcius (default) or fahrenheit
H μmS H: hour
μ: micro
m: minutes
S: seconds
- Negative reading
Low battery - replace as soon as possible to avoid inaccurate
readings.
SET Setup feature is enabled
AC+DC
For DCV and DCA functions, reading represents trueRMS total of AC
and DC measurements
True RMS Indicator for true RMS value
Ω, kΩ, mΩ
Ohm unit of resistance
Kiloohm 2x10
3
or 1000ohms
Megaohm 1x10
6
or 1,000,000ohms
Hz, kHz
MHz
Hertz unit of frequency measurement
Kilohertz 1x10
3
or 1000hertz
Megahertz 1x10
6
or 1,000,000hertz
V, mV Volts unit of measurement
Millivolt 1x10-3 or 0.001volts
μA, mA, A
Amperes unit of current
Milliamp 1x10-3 or 0.001amperes
Microamp 1x10
-6
or 0.000001amperes
F, mF
μF, nF
Farad unit of measurement
Nanofarad. 1x10
-9
or 0.000000001 farads
Microfarad.1x10-6 or 0.000001 farads
Millifarad. 1x10-3 or 0.001 farads
Automatic power off feature is turned on
Continuity test sounder
STO Data store is on
RCL Data recall is on
∆Relative mode displays present value minus stored value.
• Auto ranging (AUTO in the display) always comes on initially when you select a
new function. In auto range, the Meter selects the lowest input range possible,
ensuring that the reading appears with the highest available resolution.
• Press RANGE to enter MANUAL ranging in the present setting. You can then
select the next manual range higher by repeatedly pressing RANGE. Return to
auto ranging by pressing EXIT.
• Press RANGE when turning on the Meter, the Meter enters the analogue
resistance signal measurement mode.

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OPERATION
DC Voltage Measurement
Warning: To avoid personal injury, or damage to the meter from electric shock, please
do not attempt to measure voltages higher than 1000V although readings may be
obtained.
To measure DC voltage, connect the meter as follows:
• Insert the red test lead into the V terminal and the black test lead into the COM
terminal.
• Set the rotary switch to .
• Connect the test leads across with the object being measured. The measured DC
voltage’s true RMS value shows on the display.
• When measurement has been completed, disconnect the connection between the
test leads and the circuit under test.
Note: In each range, the meter has an input impedance of 10M Ω except 600mV range
has 3000M Ω . This loading effect can cause measurement errors in high impedance
circuits. If the circuit impedance is less than or equal to 10k Ω , the error is negligible
(0.1% or less).
Symbol Meaning
LOW Indicates lowest setup limit
AUTO The meter is set to auto range with range for best resolution selected
SEND Data output in progress
Backlight feature is on
HOLD Data hold mode is active
PEAK HOLD Peak hold mode is active
Diode test
% Frequency signal duty cycle. 4~20mA loop current as % reading
>OL Input value overload for the selected range
Analogue Bar Provides an analogue bar graph of the present input, quick response
Analogue Bar Graph
The bar graph provides an analogue indication of the measured input. For most
measurement functions, the bar graph updates 10 times per second.

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AC Voltage Measurement
Warning: To avoid personal injury, or damage to the meter from electric shock, please
do not attempt to measure voltages higher than 1000V although readings may be
obtained.
To measure AC voltage, connect the meter as follows:
• Insert the red test lead into the V terminal and the black test lead into the COM
terminal.
• Set the rotary switch to ~.
• Connect the test leads across with the object being measured. The measured AC
voltage’s true RMS value shows on the display.
• When a ACV function is selected, you can press the AC+DC button to view the AC
+ DC True RMS value in the primary display.
• When measurement has been completed, disconnect the connection between the
test leads and the circuit under test.
Note: In each range, the meter has an input impedance of 10M Ω except 600mV range
has 3000M Ω . This loading effect can cause measurement errors in high impedance
circuits. If the circuit impedance is less than or equal to 10k Ω , the error is negligible
(0.1% or less).
DC Millivoltage Measurement
Warning: To avoid damage to the meter, please do not attempt to measure voltages
higher than 400mV although readings may be obtained.
To measure DC Millivoltage, connect the meter as follows:
• Insert the red test lead into the V terminal and the black test lead into the COM
terminal.
• Set the rotary switch to mV . Press the SELECT button to cycle through
frequency and duty cycle.
• Connect the test leads across with the object being measured. The measured
RMS value shows on the display.
• When measurement has been completed, disconnect the connection between the
test leads and the circuit under test.
•
•
Note: When measuring DC Millivoltage, the Meter acts around a 2.5G Ω input
impedance in parallel with the circuit.

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DC or AC Current Measurement
Warning: Before connecting the meter in series with the circuit under test, be sure
power the circuit is off. If the fuse burns out during measurement, the meter may be
damaged and there is risk of personal injury to the operator.
Use correct terminals, function, and range for the measurement. When the test leads
are connected to the current terminals, do not connect in parallel across any circuit.
To measure current, do the following:
• Insert the red test lead into the μA mA terminal and the black test lead into the
COM terminal.
• Set the rotary switch to an appropriate measurement position in μA , mA or
A , press SELECT button to select AC measurement mode. Default is DC.
• Connect the test leads in series with the object being measured. The measured
value shows on the display.
• The measurement displays True RMS value.
• Press AC/AC+DC button to measure AC+DC current’s true RMS.
Note: If the value of current to be measured is unknown, use the maximum
measurement position, and reduce the range step by step until a satisfactory reading is
obtained.
• Each measurement time of high current (>5A) should be less than 10 seconds and
the interval time between 2 measurements should be greater than 15 minutes.
• When current measurement is complete, disconnect the test leads from the circuit
under test.
Measuring Resistance
Warning: To avoid damage to the meter or to the devices under test, disconnect circuit
power and discharge all the high-voltage capacitors before measuring resistance.
To avoid possible injury, please do not attempt to input voltages higher than 60V DC or
30V AC.
To measure resistance, connect the meter as follows:
• Insert the red test lead into the Ω terminal and black lead into the COM terminal.
• Set the rotary switch to Ω and press SELECT button to select Ω measurement
mode.
• Connect the test leads across with the object being measured. The measured
value shows on the display.

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Continuity Test
Warning: To avoid damage to the meter or to the devices under test, disconnect circuit
power and discharge all the high-voltage capacitors before testing for continuity.
To avoid personal injury, please do not attempt to input voltages higher than 60V DC or
30V AC.
To test for continuity, connect the meter as below:
• Insert the red test lead into the Ω terminal and the black test lead into the COM
terminal.
• Set the rotary switch to Ω and press SELECT button to select
measurement mode.
• Connect the test lead across with the object being measured. The buzzer sounds
if the resistance of a circuit under test is <50 Ω , the circuit is in good condition. The
buzzer does not sound if the resistance of a circuit under test is >50 Ω , the circuit
is broken.
• The measured value shows on the display and the unit is Ω .
Note: In continuity mode, the resistance range is 400 Ω , and the open circuit voltage is
approximately 1.2V.
• When continuity testing has been completed, disconnect the connection between
the test leads and the circuit under test.
Note: When measuring low resistances, the test leads and internal wiring will add
approximately 0.1 ~ 0.2 Ω of error. To obtain accurate readings in low-resistance, short-
circuit the test lead beforehand and record the reading obtained, call this reading as
X. Then use the equation: measured resistance value (Y) – (X) = accurate readings of
resistance.
• If reading with shorted test leads is not < 0.5 Ω , check for loose test leads or
possible incorrect function selection.
• When measuring high resistance (>1M Ω ), it is normal to take several seconds to
obtain a stable reading.
• The LCD displays OL indicating open-circuit or the resistor value is higher than the
maximum range of the meter.
• When testing the resistance signal from the calibrator, it is necessary to press and
hold the RANGE while turning on the Meter to change the maximum display to
4000 counts but the accuracy remains unchanged.
• When resistance measurement has been completed, disconnect the connection
between the test leads and the circuit under test.