Extech Instruments MA400 User manual

User’s Guide
MiniAmp™ Series
Clamp-on Multimeters
Models:
MA400
MA420
MA440
MA460+

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WARRANTY
EXTECH INSTRUMENTS CORPORATION warrants this
instrument to be free of defects in parts and workmanship for one
year from date of shipment (a six month limited warranty applies
on sensors and cables). If it should become necessary to return
the instrument for service during or beyond the warranty period,
contact the Customer Service Department at [phone] ext.
210 for authorization. A Return Authorization (RA) number must
be issued before any product is returned to Extech. The
sender is responsible for shipping charges, freight, insurance and
proper packaging to prevent damage in transit. This warranty does
not apply to defects resulting from action of the user such as
misuse, improper wiring, operation outside of specification,
improper maintenance or repair, or unauthorized modification.
Extech specifically disclaims any implied warranties or
merchantability or fitness for a specific purpose and will not be
liable for any direct, indirect, incidental or consequential damages.
Extech's total liability is limited to repair or replacement of the
product. The warranty set forth above is inclusive and no other
warranty, whether written or oral, is expressed or implied.
Copyright © 2001 Extech Instruments Corporation. All rights
reserved including the right of reproduction in whole or in
part in any form.

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Introduction
Congratulations on your purchase of Extech model MA400,
MA420, MA440 or MA460+ clamp-on multimeter. Properly used,
this meter will provide many years of reliable service.
Clamp meter functions common to all meters:
Autoranging
AC Current Measurements
Data Hold
Auto Power Off
Maximum Hold captures 30ms peaks
1.1" (28mm) Jaw size
MultiMeter functions common to all models:
AC/DC Voltage to 600V
Resistance to 40MΩ
Capacitance and Frequency tests
Features unique to the MA440 and MA460+ models:
Twin 4000 count LCD displays
Simultaneous display of Current/Voltage, Current/Resistance, or
Current/Temperature (MA460+)
Features common to the MA400 and MA420 models:
Single 4000 count LCD display
Relative zero function
True rms (MA420) for current and voltage measurements
Safety
International Safety Symbols
!Caution ! Refer to the explanation in this Manual
Warning ! Risk of electric shock
Earth (Ground)
Double Insulation or Reinforced insulation
Fuse
AC--Alternating Current
DC--Direct Current

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Safety Precautions
1. Improper use of this meter can cause damage, shock,
injury or death. Read and understand this users 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.
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 600V 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

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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
400.0mV 0.3% + 4d
4.000V, 40.00V, 400.0V 0.5% + 3d
600V 1.0% + 4d
NMRR: >50dB @ 50/60Hz, CMRR: >120dB @ DC, 50/60Hz,
Rs=1kΩ
Input impedance: 10MΩ, 30pF nominal, 1000MΩon the 400.0mV
range.
AC Voltage
RANGE (50Hz to 500Hz) Accuracy
4.000V, 40.00V, 400.0V 1.5% + 5d
600V 2.0% + 5d
CMRR: >60dB @ DC to 60Hz, Rs=1kΩ, Input Impedance:
10MΩ, 30pF nominal, True RMS models specified from 5% to
100% of range
AC Current (Clamp-on)
RANGE (50/60Hz) Accuracy
40.00A 1.9% + 8d
400.0A 1.9% + 8d*
600A** unspecified
True RMS model specified from 10% to 100% of range
*Accuracy specified to 350A continuous and 400A for 60 seconds
max with a 5 minute cool down interval.
** Added range to indicate instantaneous over-range current
values.
Resistance
RANGE Accuracy
400.0Ω0.8% + 6d
4.000kΩ, 40.00kΩ, 400.0kΩ, 0.6% + 4d
4.000MΩ, 1.0% + 4d
40.00MΩ, 2.0% + 4d
Open circuit voltage: 0.4V typical.

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Capacitance
RANGE Accuracy*
500.0nF, 5.000µF, 50.00µF, 500.0µF,
3000µF 3.5%* + 6d
50.00nF Not specified
*Accuracies with a film capacitor or better
*Specified with battery voltage above 2.8V (approximately half full
battery). Accuracy decreases gradually to 12% at low battery
warning voltage of approximately 2.4V.
Frequency
Function Sensitivity
(ACrms)
Range
400.0mV 150mV 10Hz to 2kHz
4.000V 3.2V 5Hz to 40kHz
40.00V 25V 5Hz to 100kHz
400.0V 100V 5Hz to 100kHz
600V 400V 5Hz to 5kHz
400µA (MA440&460+) 500µA 10Hz to 30kHz
2000µA (MA440&460+) 500µA 10Hz to 30kHz
400.0A (MA400&420) 55A 40Hz to 400Hz
Display counts: 4999, Max resolution: 0.001Hz,
Accuracy: 0.5% + 4d
Temperature (MA460+ only)
RANGE Accuracy
-4°F to 573°F 2% + 6°F
-20°C to 300°C 2% + 3°C
Accuracy does not include the type K thermocouple accuracy
DC µA (MA440 & MA460+ only)
RANGE Accuracy Burden Voltage
400.0µA 1.5% + 4d
2000µA 1.2% + 3d
2.8mV/µA
AC µA (MA440 & MA460+ only)
RANGE (50 to 500Hz) Accuracy Burden Voltage
400.0µA 2.0% + 5d
2000µA 1.5% + 5d
2.8mV/µA

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Accuracy Notes: Accuracy is ±(% reading digits + number of
digits), or as otherwise specified, at 23°C ±5°C < 75% R.H.
Model MA420 True RMS accuracies are specified from 10%
to 100% of range or as otherwise specified. Maximum Crest
Factor <1.75:1 at full scale & <3.5:1 at half scale (with
frequency component within the specified frequency
bandwidth for non-sinusoidal waveforms).
Audible Continuity: Threshold between 10Ωand 120Ω.
Response time < 100µs
Diode Test: Open circuit voltage < 1.6VDC; Test
current 0.25mA (typical)
Max Hold: Accuracy + 50 digits for changes >
25ms in duration
Digital Display: 4000-count LCD display(s); 3 per
second nominal refresh rate
Low Battery: Below approx. 2.4V
Operating Temperature: 32°to 104°F (0°to 40°C)
Storage Temperature: -4°to 140°F (-20 to 60oC), <80% R.H.
(with battery removed)
Relative Humidity: 80% to 88°F (31oC), decreasing
linearly to 50% at 104°F (40oC)
Altitude: Operating below 2000 meters
Temp. Coefficient: Nominal 0.15 x specified accuracy per
ºC (between 0 and 18oC or 28 to
40oC), or as otherwise specified
AC Sensing: True RMS on MA420, Average
sensing on MA400, MA440 and
MA460+
Auto Power Off: After 30 minutes of inactivity

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Safety: The MiniAmp™ Series meters meet
IEC61010-032(1994), EN61010-2-
032(1995), UL3111-2-032(1999).
MA440 and MA460+: Category III
600V AC & DC
MA400 and MA420: Category II 600V
AC & DC and Category III 300V AC &
DC
E.M.C.: Meets EN61326(1997, 1998/A1),
EN61000-4-2(1995), and EN61000-4-
3(1996)
In an RF field of 1V/m:
Capacitance function is not specified
µA function: Total accuracy = Acc.+50
digits
Other functions: Total acc. = Acc+ 30
digits
Performance above 1V/m is not
specified.
Overload Protection: ACA Clamp-on jaws; AC 400A
continuous
+, COM and µA terminals; 600VDC/AC
rms
Power Supply 1.5V alkaline button batteries (IEC/JIS
LR44, GAP76 or V13GA). Two
batteries for MA400 & MA420, four
batteries for MA440
3V CR2032 button battery x2 for
MA460+
Power Consumption: 2.5 mA typical. Power consumption
during auto-power off; 0.8µA (typical).
25µA typical on the MA460+
temperature function and 150µA
typical on the MA440 voltage and
current functions
Dimension: L7.5 x W2.5 x H1.26" (190mm x 63mm
x 32mm)
Weight: 6.6oz. (187g)

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Meter Description
MA440 and MA460+ (double display models)
1. Clamp jaw
2. Jaw trigger
3. ACA LCD display
4. Multimeter LCD display
5. Select button
6. Multimeter function switch
7. Multimeter input jacks
8. Hz button
9. Clamp power button
10. Data Hold/Max Hold button
MA400 and MA420 (single display models)
1. Clamp jaw
2. Jaw trigger
3. LCD display
4. Select button
5. Multimeter function switch
6. Multimeter input jacks
7. Hz button
8. Relative button
9. Data Hold/Max Hold button
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9

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Operation
NOTICE: Read and understand all warning and caution
statements listed in the safety section of this operation manual
prior to using this meter.
AC/DC Voltage Measurements
1. Connections are made through the test lead terminals.
2. Insert the black test lead into the negative COM jack and
the red test lead into the positive jack.
3. Slide the function switch to the "V" position. Press the
SELECT key momentarily to toggle between ACV and
DCV.
4. Read the voltage measurement on the display.
Note: The 400mVDC range has 1000MΩinput impedance for
the least current drain in small signal measurements. Also, the
non-zero reading experienced when the test leads are open is
normal.
AC Clamp-on Current Measurements
CAUTION: Do not make current measurements above 350A for
longer than 60 seconds. Exceeding 60 seconds may cause
damage to the meter.
1. For the MA400 and MA420, slide the function switch to the
ACA position. For the MA440/MA460+, press the Clamp
Power button.
2. Press the jaw trigger and clamp on a single conductor (fully
enclosing it; do not allow a gap to open between the two
halves of the jaw).
3. Read the current measurement on the display.
uA AC/DC Current Measurements (MA440 & MA460+ only)
1. uA Measurements are made through the test lead
terminals.
2. Insert the black test lead to the COM terminal and the red
test lead to the terminal.
3. Slide the function switch to the “uA” position.
4. Press the SELECT button to choose AC or DC current.
5. Connect the test leads in series with the circuit under test.
6. Read the current measurement on the display

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Resistance and Continuity Measurements
1. Insert the black test lead banana plug into the negative
COM jack and the red test lead banana plug into the
jack.
2. Slide the function switch to the "Ω•)))" position.
3. Press the SELECT key momentarily to select Continuity.
4. Touch the test probe tips across the circuit or part under
test. It is best to disconnect one side of the part under test
so the rest of the circuit will not interfere with the resistance
reading.
5. For Resistance tests, read the resistance on the display.
6. For Continuity tests, If the resistance is < 10Ω to 120Ω, an
audible tone will sound
Capacitance Measurements
1. Insert the black lead into the negative COM jack and the
red test lead into the positive jack.
2. Slide the function switch to the " " position.
3. Press the SELECT key repeatedly until capacitance units
(F) are displayed in the LCD.
4. The Rel function (models MA400 and MA420) can be used
to zero stray lead and circuit capacitance.
5. Touch the test leads to the capacitor to be tested and read
the measured value.
Note: Battery voltage can affect the accuracy of capacitance
measurements. Ensure that the battery is new when using the
capacitance function. Refer to the specifications.
Frequency Measurements
1. Frequency measurements are available by pressing the HZ
button when one of the following functions is selected;
* Voltage (all models via the test leads)
* ACA (MA400 and MA420 via the clamp)
* µA (MA440 and MA460+ via the test leads)
2. Perform measurements as described for the function
selected.
Notes on frequency sensitivity:
Input sensitivity varies automatically with range selected when
the HZ function is selected. Activating the HZ function while
measuring a signal will select the best sensitivity to avoid

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electrical noise that may produce an unstable reading. However,
if the HZ reading displays zero due to insufficient sensitivity,
activate the HZ function before measuring the signal to select
the highest Hz sensitivity.
Diode Test
1. Insert the black lead into the negative COM jack and the
red test lead into the positive jack
2. Slide the function switch to " " position.
3. Press the SELECT key twice until “ “ and “V” appear in
the display.
4. Touch the test probe tips to the diode or semiconductor
junction you wish to test. Note the meter reading.
5. Reverse the test lead polarity by reversing the red and
black leads. Note this reading.
6. The diode or junction can be evaluated as follows:
A. If one reading displays a value (typically 0.400V to
0.900V) and the other reading displays "OL", the diode is
good.
B. If both readings display "OL", the device is open.
C. If both readings are very small or 0, the device is
shorted.
Temperature Measurements (MA460+)
1. Insert the Type K thermocouple into the COM and input
jacks observing polarity.
2. Slide the function switch to the "oC/oF" position.
3. Use the SELECT key to toggle between oC and oF.
4. Place the Thermocouple in the area under test.
5. Wait 30 seconds for the measurement to stabilize.
6. Read the temperature on the LCD display.
Data Hold
1. Press the Data Hold key to “freeze” the reading in the
display. The annunciator “H” will appear in the display.
2. Press the Data Hold key to exit the mode.
Note: On the MA440 and MA460+ double display models, the
Data Hold feature applies only to the upper current
display (ACA).

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Max Hold
1. Press and hold for 1 second the Max Hold key to capture
and hold the maximum measured value (up to 30ms). The
annunciators “H MAX” will appear in the display
2. Press and hold for 1 second the Max Hold key to exit the
mode.
Note: The Max Hold feature applies only to the upper current
display (ACA) on the MA440 and MA460+ double display
models. It applies to the ACA, DCV and ACV functions on
the single display MA400 and MA420 models.
Relative (MA400 and MA420 only)
1. Press the Rel key once to a store the displayed reading
as the reference value. The display will now show readings
relative to the stored reference value. (display = reading -
stored value)
2. Press the Relative key again to exit the Relative mode.
Auto-ranging
If the function selected has more than one range, the meter will
auto-range to the best range and resolution. No manual ranging
is required.
Auto Power Off
The meter will enter a “sleep” mode after 30 minutes of function
switch or push button inactivity. To wake the meter up, press a
button or move the slide switch. Always slide the function switch
to the OFF position when the meter is not in use.

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
Tech Support Hotlines
781-890-7440 ext. 200
[email protected]
www.extech.com
Maintenance
WARNING
To avoid electrical shock, disconnect the meter from any circuit,
remove the test leads from the input jacks and turn OFF the meter
before opening the case. Do not operate with open case.
Cleaning and Storage
Periodically wipe the case with a damp cloth and mild detergent;
do not use abrasives or solvents. If the meter is not to be used for
periods of longer than 60 days, remove the battery and store it
separately
Battery replacement
1. Remove the two Philips head screws from the case bottom
and remove the bottom case.
2. The batteries (two LR44’s for the MA400 and MA420, four
LR44’s for the MA440, and two CR2032’s for the MA460+)
are located in button battery holders.
3. Slide the battery out the side of the holder and replace with
a new battery (observe polarity).
4. Replace the bottom case and secure with the two screws.
REPAIR AND CALIBRATION SERVICES
Extech offers complete repair and calibration services for all of
the products we sell. For periodic calibration, NIST certification or
repair of any Extech product, call customer service for details on
services available. Extech recommends that calibration be
performed on an annual basis to insure calibration integrity.