Extech Instruments MultiLog ML720 User manual

User’s Guide
MultiLog™ Digital MultiMeter
With built-in Datalogger
Model ML720

2
Introduction
Congratulations on your purchase of Extech model ML720 True rms
datalogging digital multimeter. Properly used, this meter will provide many
years of reliable service.
The MultiLog™ measures AC/DC Voltage/Current, Resistance,
Frequency, Capacitance, Temperature, Diode, and Continuity. The
MultiLog™ offers a built-in datalogger and an optical RS-232 interface.
The meter stores 43,000 data points in internal memory.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the
user must refer to the manual for further information.
This symbol, adjacent to a terminal, indicates that, under normal
use, hazardous voltages may be present
Double insulation
Safety Precautions
1. Improper use of this meter can cause damage, shock, injury or death.
Read and understand this user’s manual before operating the meter.
2. Make sure any covers or battery doors are properly closed and
secured.
3. Always remove the test leads before replacing the battery or fuses.
4. Inspect the condition of the test leads and the meter itself for any
damage before operating the meter. Repair or replace any damage
before use.
5. Do not exceed the maximum rated input limits.
6. Use great care when making measurements if the voltages are
greater than 25VAC rms or 35VDC. These voltages are considered a
shock hazard.
7. Always discharge capacitors and remove power from the device
under test before performing Capacitance, Diode, Resistance or
Continuity tests.

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8. Remove the battery from the meter if the meter is to be stored for
long periods.
9. To avoid electric shock, do not measure AC current on any circuit
whose voltage exceeds 500V AC.
10. Voltage checks on electrical outlets can be difficult and misleading
because of the uncertainty of connection to the electrical contacts.
Other means should be used to ensure that the terminals are not
"live".
11. The product is intended only for indoor use
12. If the equipment is used in a manner not specified by the
manufacturer, the protection provided by the equipment may be
impaired.
13. Pollution degree: 2
PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for
connection to circuits in which measures are taken to limit the transient
overvoltages to an appropriate low level. Note – Examples include
protected electronic circuits.
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming
equipment to be supplied from the fixed installation.
Note – Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed
installations.
Note – Examples include switches in the fixed installation and some
equipment for industrial use with permanent connection to the fixed
installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of
the installation.
Note – Examples include electricity meters and primary over-current
protection equipment

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Specifications
DC VOLTAGE
RANGE Accuracy
50.00 mV 0.12% + 2d
500.0 mV 0.06% + 2d
5.000V, 50.00V, 500.0V, 1000V 0.08% + 2d
NMRR: >60dB @ 50/60Hz, CMRR: >120dB @ DC, 50/60Hz, Rs=1kΩ
Input impedance: 10MΩ, 16pF nominal (44pF nominal for 50mV & 500mV
ranges)
AC VOLTAGE
*Specified from 30% to 100% of range
CMRR: >60dB @ DC to 60Hz, Rs=1kΩ
Input Impedance: 10MΩ, 16pF nominal (44pF nominal for 50mV &
500mV ranges)
DC CURRENT
RANGE Accuracy Burden Voltage
500.0µA, 5000µA 0.15mV/µA
50.00mA, 500.0mA 3.3mV/mA
5.000A, 10.00A* 0.2% + 4d 0.03V/A
*10A continuous, 20A for 30 seconds max with a 5 minute cool down
interval
RANGE Accuracy
50Hz/60Hz
50.00mV, 500.0mV, 5.000V, 50.00V, 500.0V, 1000V 0.5% + 3d
40Hz to 500Hz
50.00mV, 500.0mV 0.8% + 3d
5.000V, 50.00V, 500.0V 1.0% + 4d
1000V 1.2% + 4d
Up to 20kHz
50.00mV, 500.0mV 0.5dB*
5.000V, 50.00V, 500.0V 3dB*
1000V Unspecified

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AC CURRENT
RANGE Accuracy Burden Voltage
50 / 60Hz
500.0µA, 5000µA 0.6%+3d 0.15mV/µA
50.00mA, 500.0mA 0.6%+3d 3.3mV/mA
5.000A, 10.00A* 0.6%+3d 0.03V/A
40Hz to 1kHz
500.0µA, 5000µA 0.8%+4d 0.15mV/µA
50.00mA 0.8%+4d 3.3mV/mA
500.0mA 1.0%+4d 3.3mV/mA
5.000A, 10.00A* 0.8%+4d 0.03V/A
*10A continuous, 20A for 30-second max with 5 minute cool down interval
TEMPERATURE
RANGE Accuracy
-50°C TO 1000°C 0.3% + 3d
-58°F TO 1832°F 0.3% + 6d
RESISTANCE
RANGE Accuracy
50.00Ω0.2% + 6d
500.0Ω0.1% + 3d
5.000kΩ, 50.00kΩ, 500.0kΩ0.1% + 2d
5.000MΩ0.4% + 3d
50.00MΩ1.5% + 5d
Open Circuit Voltage: < 1.3VDC (< 3VDC for 50Ω& 500Ωranges)
CAPACITANCE
RANGE Accuracy*
50.00nF, 500.0nF 0.8% + 3d
5.000µF 1.0% + 3d
50.00µF 2.0% + 3d
500.0µF 3.5% + 5d
9999µF 5.0% + 5d
*Accuracies with film capacitor or better

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FREQUENCY
Function Sensitivity
(ACrms) Range
mV 300mV 10Hz - 125kHz
5V 2V 10Hz - 125kHz
50V 20V 10Hz - 20kHz
500V 80V 10Hz - 1kHz
1000V 300V 10Hz - 1kHz
Ω, Cx, diode 300mV 10Hz - 125kHz
µA, mA, A 10% F.S. 10Hz - 125kHz
Accuracy: 0.01% + 2d
Accuracy Notes: Accuracy is ±(% reading digits + number of digits), or
as otherwise specified, at 23°C ±5°C < 75% R.H. True RMS accuracies
are specified from 5% to 100% of range or as otherwise specified.
Maximum Crest Factor <3:1 at full scale & <6:1 at half scale (with
frequency component within the specified frequency bandwidth for non-
sinusoidal waveforms).
Audible Continuity:
Measurement threshold: Beeper will sound if measurement is below
20Ω. Beeper will not sound if measurement is above 200Ω. Beeper
may or may not sound if measurement is between 20 and 200Ω.
Response time: < 100µs
Digital Display: 5000-count LCD display; 5 per second
nominal refresh rate
Bar Graph Display: 52-segment bargraph; 60 per second nominal
refresh rate
Datalogging Capacity: 43000 points
Datalog Sample Rate: 0.05 (0.2 for oC/oF & Ω, 0.4 for HZ and 1 for
C), 1, 20, 40, 60, 120, 240 & 480 seconds
Low Battery: Below approx. 7V
Operating Temperature: 32°to 113°F (0°to 45°C)
Storage Temperature: -4°to 140°F (-20 to 60oC
Relative Humidity: Max 80% up to 87ºF (31ºC) decreasing
linearly to 50% at 113ºF (45ºC) <80% storage
Altitude: Operating below 2000 meters

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Temp. Coefficient:Nominal 0.15 x specified accuracy per ºC (between
0 and 18oC or 28 to 50oC), or as otherwise specified
Power Supply: 9V battery (NEDA1604, JIS006P or IEC6F22)
AC Sensing: True RMS
Auto Power Off: After 17 minutes of inactivity with no input signal
Safety: Intended for indoor use and protected by double insulation per
EN61010-1 and IEC61010-1 2nd Edition (2001) to CAT III
1000V & CAT IV 600V. The meter also meets UL3111-1(1994)*
and CSA C22.2 No. 1010-1-92* to CAT III 1000V.
Terminals (to COM) ratings:
V : CATEGORY III 1000 VOLTS AC & DC, AND
CATEGORY IV* 600 VOLTS AC & DC.
A / MAµA : CATEGORY III AND CATEGORY IV* 500
VOLTS AC AND 300 VOLTS DC.
*Category IV safety standard (for DMMs) was first released in
IEC61010-1 2nd Edition in year 2001, and was yet a UL published
standard at the time this manual was written.
UL Certification: Meters that bear the UL marking have been
investigated by UL headquarter in the USA per UL
standard UL3111-1 1st Ed to its highest CAT III rating
and international standard IEC61010-1 Second Edition
(year 2001) to CAT IV rating. The UL markings on the
meter, where applicable, are marked as “UL Listed Cat
III only” and “UL Classified to IEC61010-1 2nd Ed. Cat
IV”.
E.M.C.: Meets EN61326(1997, 1998/A1), EN61000-4-2(1995) and
EN61000-4-3(1996). Also meets former standards EN55011
(1991) and EN50082-1(1997)
In an RF field of 3V/m: Capacitance function is not specified
Other function ranges: Total Accuracy = Specified Accuracy + 30
digits. Performance > 3V/m is not specified
Overload Protection:
µA/mA Range: 0.63/500V, IR 200kA, F fuse
A Range: 12.5A/500V IR 20kA, F fuse
V Range: 1050V rms, 1450V peak
mV, Ωand other: 600VDC/VAC rms
Power Consumption: 2.7mA typical
Dimension: 7.32 x 3.43 x 1.4" with holster (186mm x 87mm x 35.5mm)
Weight: 15.17 oz. with holster (430g)

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Meter Description
1. 5000 count Liquid Crystal display
2. Function push-buttons
3. Rotary function switch
4. 10A input jack
5. V/Hz/Ω/Cap/Temp input jack
6. COM input jack
7. mA/uA current input jack
8. RS232 connector (rear)

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Features
Analog Bargraph display
Visual indication of measurement in the tradition of an analog meter
pointer. The bargraph consists of 52 discrete viewing segments. The
bargraph is useful for detecting faulty contacts, identifying
potentiometer gradations, and viewing signal spikes.
True RMS vs. Average Sensing (AC Measurements)
True RMS meters can accurately measure non-sinusoidal waveforms,
as well as distorted sine waves that contain harmonics. Average
Sensing is a fast, accurate and cost effective method of measuring
pure sine wave signals. However, non-sinusoidal waveforms cannot
accurately be measured using Average-sensing techniques.
Backlit display
The MultiLog™ is equipped with a backlight for viewing the LCD
display in poorly lit areas.
Data Hold
The HOLD function freezes the reading on the display for later
viewing.
Manual and Automatic Ranging
The MultiLog™ series multimeters are Autoranging, with manual
override.
Smart Power Auto Power Off
Smart Power shuts the meter down automatically after approximately
17 minutes of inactivity.
Audible Beeper
To disable the audible meter tones, press and hold the Hz key while
powering the meter.
Automatic Test Lead Resistance Compensation
Automatically compensates for the resistance of the test leads, as well
as the internal protection circuitry automatically, ensuring greater
accuracy of low resistance measurements.
Datalogging
The MultiLog™ series of multimeters store reading for review on the
LCD display or downloading to a pc using the supplied software.

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Operation
Measurement Considerations
NOTICE: Read and understand all warning and caution statements
listed in the safety section of this operation manual prior to using this
meter.
1. Always move the rotary function switch to the OFF position when the
meter is not in use. This meter has Auto Power OFF that
automatically shuts the meter OFF if 17 minutes elapse without
activity.
2. If "OL" appears on the display during a measurement, the
measurement exceeds the range selected. Change to a higher range.
AC/DC Voltage Measurements
1. Insert the black test lead into the negative COM jack and the red test
lead into the positive Vjack.
2. Set the function switch to the "VAC" "VDC" "mV" position. Press the
SELECT key momentarily to toggle between AC and DC.
3. Read the voltage measurement on the display
AC/DC Current Measurements
CAUTION: Do not make current measurements at 20A for longer than
30 seconds. Exceeding 30 seconds may cause damage to the meter
and/or the test leads.
1. Insert the black test lead into the negative COM jack.
2. For current measurements up to 4000µA, set the function switch to
the "µA" position and insert the red test lead into the mA-µAjack.
3. For current measurements up to 400mA, set the function switch to the
"mA" position and insert the red test lead into the mA-µAjack.
4. For current measurements up to 10A, set the function switch to the
"A" position and insert the red test lead into the Ajack.
5. Press the SELECT key momentarily to toggle between AC and DC.
6. Remove power from the circuit under test and open the circuit at the
point where you wish to measure current.
7. Touch the black test probe tip to the negative side of the circuit and
touch the red test probe tip to the positive side of the circuit.
8. Apply power to the circuit.
9. Read the current on the display