Extech Instruments EX540 User manual

User's Guide
Wireless TRMS Multimeter
Model EX540

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Introduction
This meter measures AC/DC Voltage, AC/DC Current, Resistance, Capacitance, Frequency
(electrical & electronic), Duty Cycle, Diode Test, and Continuity plus Thermocouple
Temperature. It can store and recall data. It features a waterproof, rugged design for heavy
duty use. This meter can transmit data wirelessly when linked to a PC. Proper use and care
of this meter will provide many years of reliable service.
Safety
This symbol adjacent to another symbol, terminal or operating device
indicates that the operator must refer to an explanation in the Operating
Instructions to avoid personal injury or damage to the meter.
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.
This symbol advises the user that the terminal(s) so marked must not be
connected to a circuit point at which the voltage with respect to earth
ground exceeds (in this case) 1000 VAC or VDC.
This symbol adjacent to one or more terminals identifies them as being
associated with ranges that may, in normal use, be subjected to
particularly hazardous voltages. For maximum safety, the meter and its
test leads should not be handled when these terminals are energized.
This symbol indicates that a device is protected throughout by double
insulation or reinforced insulation.
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
MAX
1000V

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SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be operated with caution. The rules
listed below must be carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the specified maximum:
Input Protection Limits
Function Maximum Input
V DC or V AC 1000VDC/AC rms
mA AC/DC 500mA 1000V fast acting fuse
A AC/DC 10A 1000V fast acting fuse (20A for 30 seconds
max every 15 minutes)
Frequency, Resistance, Capacitance,
Duty Cycle, Diode Test, Continuity 1000VDC/AC rms
Temperature 1000VDC/AC rms
Surge Protection: 8kV peak per IEC 61010
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 1000V above
earth ground.
4. NEVER connect the meter leads across a voltage source while the function switch is in
the current, resistance, or diode mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when
making resistance or diode tests.
6. ALWAYS turn off the power and disconnect the test leads before opening the covers to
replace the fuse or batteries.
7. NEVER operate the meter unless the back cover and the battery and fuse covers are in
place and fastened securely.
8. If the equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired.

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Controls and Jacks
1. 40,000 count LCD display
2. STORE(<RECALL) button
3. MAX/MIN (_)button
4. MODE button
5. RANGE(SETUP) button
6. Function switch
7. mA, µA and 10A input jacks
8. COM input jack
9. Positive input jack
10. Backlight button
11. EXIT(AC+DC) button
12. HOLD(PEAKHOLD>) button
13. REL(+) button
Note: Tilt stand and battery compartment are on rear of unit.
Symbols and Annunciators
•))) Continuity
Diode test
Battery status
n nano (10-9) (capacitance)
µ micro (10-6) (amps, cap)
m milli (10-3) (volts, amps)
A Amps
k kilo (103) (ohms)
F Farads (capacitance)
M mega (106) (ohms) RF transmitter active
Ω Ohms PEAK Peak Hold
Hz Hertz (frequency) V Volts
% Percent (duty ratio) Relative
AC Alternating current AUTO Autoranging
DC Direct current HOLD Display hold
ºF Degrees Fahrenheit ºC Degrees Centigrade
MAX Maximum MIN Minimum
N0. Serial number S second
SET Set up parameter AC+DC Alternating current + Direct current
TRMS True RMS STO Store
RCL Recall AUTO Auto Range
Auto Power off enabled Backlight
1
2
3
4
5
6
7
13
12
11
10
9
8

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Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are very
dangerous and should be measured with great care.
1. ALWAYS turn the function switch to the OFF position when the meter is not in use.
2. If “OL” appears in the display during a measurement, the value exceeds the range
you have selected. Change to a higher range.
DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or
OFF. Large voltage surges may occur that can damage the meter.
1. Set the function switch to the VDC position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
3. 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.
4. Read the voltage in the display.
AC VOLTAGE (FREQUENCY, DUTY CYCLE) MEASUREMENTS
WARNING: Risk of Electrocution. The probe tips may not be long enough to contact the
live parts inside some 240V outlets for appliances because the contacts are recessed
deep in the outlets. As a result, the reading may show 0 volts when the outlet actually has
voltage on it. Make sure the probe tips are touching the metal contacts inside the outlet
before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or
OFF. Large voltage surges may occur that can damage the meter.
1. Set the function switch to the VAC/Hz/% position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert red test lead banana plug into the positive Vjack.
3. Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the “hot” side of the circuit.
4. Read the voltage in the main display and the frequency in the right
auxiliary display
5. Press the MODE button to indicate “Hz”.
6. Read the frequency in the main display.
7. Press the MODE button again to indicate “%”.
8. Read the % of duty cycle in the main display.
9. With ACV in the main display, press EXIT for 2 seconds to measure AC+DC.

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mV VOLTAGE MEASUREMENTS
CAUTION: Do not measure mV voltages if a motor on the circuit is being switched ON
or OFF. Large voltage surges may occur that can damage the meter.
1. Set the function switch to the mV position.
2. Press the MODE button to indicate “DC”or ““AC ”, or in AC range press
EXIT for two seconds and chose ”AC+DC”
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 the negative side of the circuit. Touch
the red test probe tip to the positive side of the circuit.
5. Read the mV voltage in the main display.
6. With AC mV in the main display, press EXIT for 2 seconds to measure
AC+DC.
DC CURRENT MEASUREMENTS
CAUTION: Do not make 20A current measurements 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 banana plug into the negative COM jack.
2. For current measurements up to 4000µA DC, set the function switch to
the µA position and insert the red test lead banana plug into the µA/mA
jack.
3. For current measurements up to 400mA DC, set the function switch to
the mA position and insert the red test lead banana plug into the µA/mA
jack.
4. For current measurements up to 20A DC, set the function switch to the
10A/HZ/% position and insert the red test lead banana plug into the 10A
jack.
5. Press the MODE button to indicate “DC” on the display.
6. Remove power from the circuit under test, then open up 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.
Touch the red test probe tip to the positive side of the circuit.
8. Apply power to the circuit.
9. Read the current in the display.

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AC CURRENT (FREQUENCY, DUTY CYCLE) MEASUREMENTS
CAUTION: Do not make 20A current measurements 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 banana plug into the negative COM jack.
2. For current measurements up to 4000µA AC, set the function switch to
the µA position and insert the red test lead banana plug into the µA/mA
jack.
3. For current measurements up to 400mA AC, set the function switch to
the mA position and insert the red test lead banana plug into the µA/mA
jack.
4. For current measurements up to 20A AC, set the function switch to the
10A/HZ/% position and insert the red test lead banana plug into the 10A
jack.
5. Press the MODE button to indicate “AC” on the display.
6. Remove power from the circuit under test, then open up the circuit at the
point where you wish to measure current.
7. Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the “hot” side of the circuit.
8. Apply power to the circuit.
9. Read the current in the display. In the 10AAC range, right auxiliary display frequency.
10. Press and hold the MODE button to indicate “Hz”.
11. Read the frequency in the display.
12. Momentarily press the MODE button again to indicate “%”.
13. Read the % duty cycle in the display.
14. Press and hold the MODE button to return to current measurement.
10. With ACA in the main display, press EXIT for 2 seconds to measure AC+DC.
RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under test and
discharge all capacitors before taking any resistance measurements. Remove the
batteries and unplug the line cords.
1. Set the function switch to the Ω CAP position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Ωjack.
3. Press the MODE button to indicate “Ω” on the display.
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. Read the resistance in the display.

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CONTINUITY CHECK
WARNING: To avoid electric shock, never measure continuity on circuits or wires that
have voltage on them.
1. Set the function switch to the ΩCAP position.
2. Insert the black lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Ωjack.
3. Press the MODE button to indicate“ "and “Ω”on the display
4. Touch the test probe tips to the circuit or wire you wish to check.
5. If the resistance is less than approximately 35Ω, the audible signal will
sound. If the circuit is open, the display will indicate “OL”.
DIODE TEST
1. Set the function switch to the ΩCAP position.
2. Insert the black test lead banana plug into the negative COM jack and
the red test lead banana plug into the positive Vjack.
3. Press the MODE button to indicate“ “ and “V” on the display.
4. Touch the test probes to the diode under test. Forward voltage will
typically indicate 0.400 to 0.700V. Reverse voltage will indicate “OL”.
Shorted devices will indicate near 0V and an open device will indicate
“OL” in both polarities.
CAPACITANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under test and
discharge all capacitors before taking any capacitance measurements. Remove the
batteries and unplug the line cords.
1. Set the rotary function switch to the ΩCAP position.
2. Insert the black test lead banana plug into the negative COM jack.
3. Insert the red test lead banana plug into the positive Vjack.
4. Press the MODE button to indicate “F”
5. Touch the test leads to the capacitor to be tested.
6. Read the capacitance value in the display

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TEMPERATURE MEASUREMENTS
1. Set the function switch to the Temp position.
2. Insert the Temperature Probe into the input jacks, making sure to
observe the correct polarity.
3. Press the MODE button to indicate “ºF” or “ºC”
4. Touch the Temperature Probe head to the part whose temperature
you wish to measure. Keep the probe touching the part under test
until the reading stabilizes (about 30 seconds).
5. Read the temperature in the display.
Note: The temperature probe is fitted with a type K mini connector. A mini connector to
banana connector adaptor is supplied for connection to the input banana jacks.
FREQUENCY (DUTY CYCLE) MEASUREMENTS (ELECTRONIC)
1. Set the rotary function switch to the Hz/% position.
2. Insert the black lead banana plug into the negative COM jack and the red test lead
banana plug into the positive Hz jack.
3. Touch the test probe tips to the circuit under test.
4. Read the frequency on the display.
5. Press the MODE button to indicate “%”.
6. Read the % duty cycle in the display.
% 4 – 20mA MEASUREMENTS
1. Set up and connect as described for DC mA measurements.
2. Set the rotary function switch to the 4-20mA% position.
3. The meter will display loop current as a % with 0mA=-25%, 4mA=0%, 20mA=100%,
and 24mA=125%.
AUTORANGING/MANUAL RANGE SELECTION
When the meter is first turned on, it automatically goes into AutoRanging. This
automatically selects the best range for the measurements being made and is generally
the best mode for most measurements. For measurement situations requiring that a range
be manually selected, perform the following:
1. Press the RANGE key. The “AUTO” display indicator will turn off.
2. Press the RANGE key to step through the available ranges until you select the range
you want.
3. To exit the Manual Ranging mode and return to Autoranging, press EXIT
Note: Manual ranging does not apply for the Temperature functions.
MAX/MIN
1. Press the MAX/MIN key to activate the MAX/MIN recording mode. The display icon
"MAX" will appear. The meterleft auxiliary displaywill display and hold the maximum
reading and will update only when a new “max” occurs.The display icon "MIN" will
appear. The right auxiliary displaymeter will display and hold the minimum reading
and will update only when a new “min” occurs.
2. To exit MAX/MIN mode press EXIT

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RELATIVE MODE
The relative measurement feature allows you to make measurements relative to a stored
reference value. A reference voltage, current, etc. can be stored and measurements made
in comparison to that value. The displayed value is the difference between the reference
value and the measured value.
1. Perform the measurement as described in the operating instructions.
2. Press the REL button to store the reading in the display and the "▲" indicator will
appear on the display.
3. The Right auxiliary display displays the initial reading (the stored value)
4. The Left auxiliary display displays the actual currently measured value.
5. Main display displays the Relative value (currently measured value minus the stored
value).
DISPLAY BACKLIGHT
Press the key to turn the backlight on. The backlight will automatically turn off after
SET time. Press the EXIT button to exit the backlight on mode.
HOLD
The hold function freezes the reading in the display. Press the HOLD key momentarily to
activate or to exit the HOLD function.
PEAK HOLD
The Peak Hold function captures the peak AC or DC voltage or current. The meter can
capture negative or positive peaks as fast as 1 millisecond in duration. Momentarily press
the PEAK button, “PEAK” and “MAX” will display in left auxiliary display. MIN” will
display in right auxiliary display. The meter will update the dispay each time a lower
negative peak occurs. Press the EXIT button to exit the PEAK HOLD mode. Auto Power
Off feature will be disabled automatically in this mode.
DATA STORAGE
1. Set the function switch to the measurement function desired.
2. Press the STORE button to enter the STORE function. The left upper aux display
indicates the current storage location (0000 to 9999). New measurements will begin
storing into the next location.
3. Press the PEAKHOLD button to change into the initial storage number 0000. (Press it
again to change back). On the right upper aux display shows XXXX which states how
many current storage locations are used.
4. Press STORE button again to enter into recording interval time set up function.
5. The left upper aux display indicates 0000 S, which is the recording sample rate; use
the + & - buttons to select the sample rate desired (0 to 255 sec)
6. Set the sample rate to 0000 S for manual recording. In this mode, each press of the
STORE button will save one measurement reading.
7. Set the sample rate to 1 to 255 S for automatic recording. In this mode, pressing the
STORE button will start data recording at the set sample rate.
8. Press the EXIT button to end the recording session.