Extech Instruments EX623 User manual

User's Guide
400Amp True RMS AC/DC Clamp
Meter with IR Thermometer
Model EX623
Patented

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Introduction
Congratulations on your purchase of this Extech EX623 True RMS Clamp Meter. This meter
measures AC Current, DC Current, AC/DC Voltage, Resistance, Capacitance, Frequency,
Diode Test, Duty Cycle and Continuity. Special features include Dual Input Thermocouple
Temperature, Non-Contact IR Temperature and Non-Contact Voltage detector. The double
molded case is designed for heavy duty use. This meter is shipped fully tested and calibrated
and, with proper use, will provide years of reliable service.
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
This WARNING symbol indicates a potentially hazardous situation, which
if not avoided, could result in death or serious injury.
This CAUTION symbol indicates a potentially hazardous situation, which
if not avoided, may result damage to the product.
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
WARNING
CAUTION

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SAFETY NOTES
•Do not exceed the maximum allowable input range of any function.
•Do not apply voltage to meter when resistance function is selected.
•Set the function switch OFF when the meter is not in use.
•Remove the battery if meter is to be stored for longer than 60 days.
WARNINGS
•Set function switch to the appropriate position before measuring.
•When measuring volts do not switch to current/resistance modes.
•Do not measure current on a circuit whose voltage exceeds 600V.
•When changing ranges always disconnect the test leads from the circuit under test.
CAUTIONS
•Improper use of this meter can cause damage, shock, injury or death. Read and
understand this user manual before operating the meter.
•Always remove the test leads before replacing the battery or fuses.
•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.
•Use great care when making measurements if the voltages are greater than 25VAC
rms or 35VDC. These voltages are considered a shock hazard.
•Always discharge capacitors and remove power from the device under test before
performing Diode, Resistance or Continuity tests.
•Voltage checks on electrical outlets can be difficult and misleading because of the
uncertainty of connection to the recessed electrical contacts. Other means should be
used to ensure that the terminals are not "live".
•If the equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired.
Function Maximum Input
A AC, 400A DC/AC
A DC 400A DC/AC
V DC, V AC 600V DC/AC
Resistance, Capacitance, Frequency, Diode Test 250V DC/AC
μA 4000 μA
Type K Temperature 30V DC, 24V AC

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Description
Meter Description
1. Current clamp
2. Clamp opening trigger
3. IR thermometer and Laser Button
4. HOLD/BACKLIGHT button
5. MODE / ZERO button
6. Backlit LCD Display
7. Type K input jacks
8. Multimeter input jacks
9. IR thermometer sensor and Laser pointer (rear)
10. Function switch
11. PEAK button
12. MAX/MIN button
13. Range button
14. Thermocouple display button
15. Battery compartment (rear)
16. Non-Contact Voltage Detector
17. NCV LED indicator
18. Input shutter
Display icons Description
HOLD Data Hold
APO Auto Power Off
AUTO Autoranging
PPeak Hold
DC Direct Current
AC Alternating Current
MAX Max reading
MIN Min reading
Low battery
ZERO DCA or CAP zero
mV or V Milli-volts or Volts (Voltage)
ΩOhms (Resistance)
A Amperes (Current)
F Farad (Capacitance)
Hz Hertz (Frequency)
% Duty Ratio
oF and oC Fahrenheit and Celsius units (Temperature)
T1, T2, T1-T2Therocouple 1, Thermocouple 2, Thermocouple difference
n, m, μ, M, k Unit of measure prefixes: nano, milli, micro, mega, and kilo
•))) Continuity test
Diode test
Laser pointer

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Operation
NOTES: Read and understand all Warning and Caution statements in this operation
manual prior to using this meter. Set the function select switch to the OFF position when
the meter is not in use.
Input Shutter
The Input Shutter inhibits simultaneous connection to the thermocouple jacks and the
DMM input jacks. This is a safety feature which prevents a potentially hazardous condition
from existing during high voltage measurements. Slide the shutter up for test lead
measurements or slide it down for thermocouple temperature measurements.
Non-Contact Voltage Detector
WARNING: Risk of Electrocution. Before use, always test the Voltage Detector on a
known live circuit to verify proper operation.
1. Rotate the Function switch to any measurement
position.
2. Place the detector probe tip on the conductor to be
tested.
3. If AC voltage is present, the NCV detector light will
turn on with a steady red light.
NOTE: The conductors in electrical cord sets are often
twisted. For best results, move the probe tip along
a length of the cord to assure placing the tip in
close proximity to the live conductor.
NOTE: The detector is designed with high sensitivity. Static electricity or other sources of
energy may randomly trip the sensor. This is normal operation.

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AC/DC Current Measurements
WARNING: Disconnect the test leads before making clamp measurements.
1. Rotate the Function switch to the
400AAC/DC position
2. Press the MODE button to select AC
or DC.
3. Press the trigger to open jaw. Fully
enclose only one conductor.
4. Read the current value in the display.
5. If the value is less than 40A, rotate
the function switch to the 40AAC/DC
position to improve resolution.
DCA Zero
The Zero feature removes offset values and improves accuracy for DC current
measurements. To perform a zero, select ADC and, with no conductor in the jaw, press
and hold the MODE ZERO button for two beeps. The display will zero. The offset value
is now stored and removed from all measurements.
Frequency
When ACV is selected, the measured frequency can be viewed in the lower display.
AC/DC Voltage Measurements
CAUTION: Do not measure voltages if a motor on the circuit is being switched ON or
OFF. Large voltage surges may occur that can damage the meter.
1. Slide the input shutter to the up position.
2. Rotate the function switch to the V position.
3. Press the MODE button to select AC or DC Voltage.
4. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
5. Touch the black test probe tip to the negative side of the circuit.
Touch the red test probe tip to the positive side of the circuit.
6. Read the voltage value in the display.
Frequency
When ACA is selected, the measured frequency can be viewed in the
lower display.

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Resistance Measurements
Note: Remove power from the device under test before making resistance measurements
1. Slide the input shutter to the up position.
2. Set the function switch to the Ω position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the resistance value in the display.
Continuity Test
1. Connect as described for resistance measurements.
2. Press the MODE button to select continuity•))).
3. Touch the test probe tips across the circuit or component under test.
4. If the resistance is < 50Ω, a tone will sound.
Diode Test
1. Connect as described for resistance measurements
2. Press the MODE button to select diode test .
3. Touch the test probe tips to the diode or semiconductor junction under test. Note the
meter reading.
4. Reverse the test lead polarity by reversing the red and black leads. Note this reading.
5. The diode or junction can be evaluated as follows:
If one reading displays a value (typically 0.400V to 01.800V) and the other
reading displays OL, the diode is good.
If both readings display OL the device is open.
If both readings are very small or ‘0’, the device is shorted.

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Capacitance Measurements
WARNING: To avoid electric shock, discharge the capacitor before measuring.
1. Slide the input shutter to the up position.
2. Rotate the function switch to the capacitance position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the capacitance value in the display.
Note: For very large values of capacitance measurement time can be
several seconds before the final reading stabilizes.
Note: The Zero feature removes stray test lead capacitance to improve
the accuracy of low value capacitance measurements. To perform
a zero, Press and hold the MODE ZERO button for two beeps. The
display will zero. The offset value is now stored and is removed
from all measurements.
.
Frequency and Duty Ratio Measurements
1. Slide the input shutter to the up position.
2. Rotate the function switch to the Hz % Position.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Hz jack.
4. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
5. Read the Frequency value on the upper large display.
Read the Duty Ratio on the lower small display.
6. Press the MODE button to display the Duty Ratio on the large
display.

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μA DC/AC Current Measurements
1. Slide the input shutter to the up position.
2. Rotate the function switch to the μA position.
3. Press the MODE button to select AC or DC.
4. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive μAjack.
5. Turn power to the circuit under test off and make a break in the circuit.
6. Insert the meter in series with the circuit;
Touch the black test probe tip to the negative side of the break.
Touch the red test probe tip to the positive side of the break.
7. Turn circuit power on.
8. Read the current value in the display.
Type K Temperature Measurements
1. Slide the input shutter to the down position.
2. Rotate the function switch to the TYPE K temperature position.
3. Press the MODE button to select °F or °C.
4. Insert the Temperature Probe(s) into the T1 and/or T2 type k sockets.
5. Place the temperature probe tip(s) where needed.
6. Read the temperature on the display.
7. Press the T1-T2 button to step through the display combinations:
Upper display Lower display
a. T1 T2
b. T2 T1
c. T1-T2 T1
d. T1- T2 T2
Note: In case of an open input or a temperature overrange, the meter will display “- - - -” .

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Non-Contact InfraRed Temperature Measurements
1. Rotate the function switch to the IR position.
2. Press the MODE button to select °F or °C.
3. Aim the infrared sensor (rear of the meter) at the
surface to be measured.
4. Press the IRT button to turn on the IR
thermometer and laser pointer. The laser pointer
identifies the surface spot to be measured.
5. The area of the surface to be measured must be
larger than the spot size as determined by the
distance to spot size specification.
6. Read the temperature in the large upper display.
When the IRT button is released the displayed temperature will be held for approx. 10
seconds.
7. Read the MAX temperature in the lower display.
Press the MAX/MIN button to toggle the lower display between the maximum and
minimum measured values.
WARNING: Do not directly view or direct the laser pointer at
an eye. Low power visible lasers do not normally present a
hazard, but may present some potential for hazard if viewed
directly for extended periods of time.
IR Spot to Distance Diagram
The 8:1 spot to distance ratio determines
the size of the measured surface area with
respect to the distance the meter is held
away from the surface.
IR Measurement Notes
1. The object under test should be larger than the spot (target) size calculated by the
field of view diagram.
2. If the surface of the object under test is covered with frost, oil, grime, etc., clean
before taking measurements.
3. If an object's surface is highly reflective, apply masking tape or flat black paint to the
surface before measuring.
4. The meter may not make accurate measurements through transparent surfaces such
as glass.
5. Steam, dust, smoke, etc. can obscure measurements.
6. To find a hot spot, aim the meter outside the area of interest then scan across (in an
up and down motion) until the hot spot is located.

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Data Hold
To freeze the LCD reading, press the HOLD button. While data hold is active, the HOLD
icon appears on the LCD. Press the HOLD button again to return to normal operation.
MAX/MIN
1. Press the MAX/MIN button to activate the MAX/MIN recording mode. The display icon
"MAX" will appear. The meter will begins recording and displaying the maximum
value measured.
2. Press the MAX/MIN button and “MIN” will appear. The meter will display the minimum
value measured during the recording session.
3. Press the MAX/MIN button and “MAX MIN” will appear. The meter will display the
present reading, but will continue to update and store the max and min readings.
4. To exit MAX/MIN mode press and hold the MAX/MIN button for 2 seconds.
Peak Hold
When ACA or ACV is selected, pressing the PEAK button enables the peak capture circuit.
The meter will now capture and display the maximum and minimum peaks of the
waveform.
RANGE
In the Voltage, Resistance, Capacitance, Frequency or uA function the meter automatically
selects the best range for the measurements being made. For measurement situations
requiring that a range be manually selected, perform the following:
1. Press the RANGE button. The “AUTO” display icon will turn off.
2. Press the RANGE key to step through the available ranges. Observe the decimal
point and units displayed until the preferred range is located.
3. To exit the Manual Ranging mode and return to Autoranging, press and hold the
RANGE key for 2 seconds.
LCD Backlight
The LCD is equipped with backlighting for easier viewing, especially in dimly lit areas.
Press and hold the HOLD/ button for 2 seconds to turn the backlight on. The backlight
will automatically turn off after 30 seconds.
Automatic Power OFF with Disable
In order to conserve battery life, the meter will automatically turn off after approximately 30
minutes. To turn the meter on again, turn the function switch to the OFF position and then
to the desired function position.
To disable APO:
1. From the OFF position, hold the MODE button and rotate the FUNCTION switch to a
measurement function.
2. will appear in the display
3. Release the MODE button
4. APO is now disabled (APO icon is off) and will be reset when the Function switch is
returned to the OFF position.
Low battery indication
When the icon appears in the display, the battery should be replaced. Refer to the
battery replacement procedure in the maintenance section.

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Maintenance
WARNING: To avoid electrical shock, disconnect the meter from any circuit, remove the
test leads from the input terminals, and turn OFF the meter before opening the case. Do
not operate the meter with an 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 60 days or more, remove the battery and store it
separately.
Battery Replacement
1. Remove the Phillips head screw that secures the rear battery door
2. Open the battery compartment
3. Replace the 9V battery
4. Secure the battery compartment door
Fuse Replacement
1. Remove the battery
2. Remove the Phillips head screws (2) that secures the rear cover.
3. Replace the fuse with one of equal rating. (500mA, 660V fast blow [SIBA 70-180-40])
4. Replace the rear cover and battery
Warranty
EXTECH INSTRUMENTS CORPORATION(a FLIR company) 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 to 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 (781)
890-7440 ext. 210 for authorization or visit our website www.extech.com for contact information. 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.
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Care Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.

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Specifications
Function Range Resolution Accuracy
(% of reading + digits)
400.0 AAC 0.1AAC Current
50/60 Hz
True RMS 40.00 AAC 0.01A ±(1.5% + 5 digits)
400.0 ADC 0.1ADC Current
40.00 ADC 0.01A ±(1.5% + 5 digits)
400.00μA 0.01μA
AC/DC μA
Current 4000.0μA 0.1μA
DC: ±(1.0% + 2 digits)
AC: ±(1.5% + 2 digits)
400.0 mVAC 0.1mV ±(1.0% + 20 digits)
4.000 VAC 0.001V
40.00 VAC 0.01V
400.0 VAC 0.1V
AC Voltage
50/60 Hz
True RMS
600 VAC 1V
±(2.0% + 5 digits)
400.00 mVDC 0.01mV
4.0000 VDC 0.0001V
40.000 VDC 0.001V
400.00 VDC 0.01V
±(0.1% + 2 digits)
DC Voltage
600.0 VDC 0.1V ±(1.0% + 2 digits)
400.00Ω0.01Ω±(0.8% + 20 digits)
4.0000kΩ0.0001kΩ
40.000kΩ0.001kΩ
400.00kΩ0.01kΩ
4.0000MΩ0.0001MΩ
±(0.8% + 4 digits)
Resistance
40.000MΩ0.001MΩ±(2.5% + 10 digits)
400.00nF 0.01nF ±(5.0% + 40 digits)
4000.0nF 0.1nF ±(3.0% + 10 digits)
400.00µF 0.01µF ±(3.5% + 10 digits)
4000.0µF 0.1µF
Capacitance
40.000mF 0.001mF
±(5.0% + 10 digits)
400.00Hz 0.01Hz ±(1.0% + 3 digits)Frequency
(clamp) Sensitivity: 5Arms minimum

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Function Range Resolution Accuracy
(% of reading + digits)
40.000Hz 0.001Hz ±(0.3% + 3 digits)
400.00Hz 0.01Hz
4000.0Hz 0.1Hz
40.000kHz 0.001kHz
400.00kHz 0.01kHz
4000.0kHz 0.1kHz
40.000MHz 0.001MHz
±(0.3% + 2 digits)
100.00MHz 0.01MHz Not specified
Frequency
(test leads)
Sensitivity: 5 to 5kHz; 0.8Vrms min., 5kHz to 150kHz; 5Vrms min
0.5% to 99.0% 0.1% ±(1.2% + 2 digits)Duty Cycle
Pulse width: 100μs to 100ms, Frequency: 5Hz to 150kHz
-58 to -4°F
-50 to -19°C ±13°F/7°C
-4 to 31°F
-20 to -1°C ±(1.0% + 2°F/1°C)
32°F
0°C ±2°F/1°C
33 to 211°F
1 to 100°C ±(1.0% + 2°F/1°C)
212 to 718°F
101 to 399°C ±(1.5% + 3°F/2°C)
719 to 1832°F
400 to 1000°C
0.1° <1000°
1° >1000°
±(2.5% + 7°F/4°C)
Temperature
Type K
Specification does not include probe accuracy
-58 to -4°F
-50 to -20°C ±9°F/5°C
-4 to 31°F
-20 to -1°C ±2% of reading or ±4°F/2°C whichever is greater
32°F
0°C ±2°F/1°C
Temperature
IR
33 to 518°F
1 to 270°C
0.1°
±2% of reading or ±3°F/2°C
whichever is greater

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
Support line [phone]
Technical support: Extension 200; E-mail: [email protected]m
Repair & Returns: Extension 210; E-mail: [email protected]
Product specifications subject to change without notice
For the latest version of this User’s Guide, Software updates, and other
up-to-the-minute product information, visit our website: www.extech.com
General Specifications
Clamp jaw opening 1.25" (32mm) approx.
Display Dual 40,000/4,000 count backlit LCD
Continuity check Threshold 50Ω; Test current < 0.5mA
Diode test Test current of 0.3mA typical;
Open circuit voltage [2.8VDC typical
Low Battery indication Battery symbol is displayed
Over-range indication ‘OL’ display
Measurement rate 2 readings per second, nominal
Peak detector >1ms
Thermocouple sensor Type K thermocouple required
Fuse 500mA, ceramic fast blow
IR Spectral response 6 to 16µm (models EX622 and EX623)
IR Emissivity 0.95 fixed (models EX622 and EX623)
IR distance ratio 8:1 (models EX622 and EX623)
Laser pointer Class 2 laser < 1mW power; Wavelength is 630 to 670nm
Input Impedance 10MΩ(VDC and VAC)
AC bandwidth 50 to 400Hz (AAC and VAC)
AC response True rms (AAC and VAC)
Crest Factor 3.0 in 40A and 400A ranges, 1.4 in 1000A range (50/60Hz
and 5% to 100% of range)
Operating Temperature 41°F to 104°F (5°C to 40°C)
Storage Temperature -4°F to 140°F (-20°C to 60°C)
Operating Humidity Max 80% up to 87°F (31°C) decreasing linearly to 50% at
104°F(40°C)
Storage Humidity <80%
Operating Altitude 7000ft. (2000meters) maximum.
Battery One (1) 9V Battery (NEDA 1604)
Auto power OFF After approx. 30 minutes, with disable
Dimensions & Weight 9.5x3.8x1.75” (241x96x44.5mm); 13.6 oz. (386g)
Safety For indoor use and in accordance with the requirements for
double insulation to IEC1010-1 (2001): EN61010-1 (2001)
Overvoltage Category III 600V and Category II 1000V,
Pollution Degree 2
Approvals CE,
Patent notice U.S. Patent 7163336
Copyright ©2008 Extech Instruments Corporation (a FLIR company)
All rights reserved including the right of reproduction in whole or in part in any form.