General DMM550 User manual

RUGGED TRUE RMS
MULTIMETER
WITH NCV DETECTION
USER’S MANUAL
DMM550
Please read this manual carefully and thoroughly
before using this product.
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TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What's in the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Product Overview . . . . . . . . . . . . . . . . . . . . . . . . 4 –5
afety Instructions . . . . . . . . . . . . . . . . . . . . . . . 6 –8
etup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Operating Instructions. . . . . . . . . . . . . . . . . . . . 9 – 19
General Instructions . . . . . . . . . . . . . . . . . . . . 9 – 12
Ranging Options . . . . . . . . . . . . . . . . . . . . 9 – 10
Holding Readings . . . . . . . . . . . . . . . . . . . . . . 10
Tracking Maximum and Minimum Readings. . 10
Making Relative Measurements . . . . . . . 10 – 11
Disabling Auto Power Off (APO). . . . . . . . . . . . 11
Using the Analog Bar Graph . . . . . . . . . . . . . . 11
Turning on the Backlight. . . . . . . . . . . . . . . . . 12
Measuring AC or DC Current. . . . . . . . . . . . . 12 – 13
Measuring AC or DC Voltage. . . . . . . . . . . . . 13 – 15
Using the Non-contact Voltage Detector . . 14 – 15
Measuring Resistance . . . . . . . . . . . . . . . . . . . . . 15
Checking for Continuity . . . . . . . . . . . . . . . . . . . . 16
Checking the Integrity of a Diode . . . . . . . . . . . . . 16
Measuring Capacitance . . . . . . . . . . . . . . . . . . . . 17
Measuring Frequency and Duty Cycle . . . . . . . . . 17
Measuring Temperature . . . . . . . . . . . . . . . . 18 – 19
pecifications . . . . . . . . . . . . . . . . . . . . . . . . . 18 – 21
Operating & Maintenance Tips . . . . . . . . . . . . . . . . 21
Warranty Information . . . . . . . . . . . . . . . . . . . 22 – 23
Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . 23
2
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INTRODUCTION
Thank you for purchasing eneral Tools & Instruments’
( eneral’s) DMM550 Rugged True RMS Multimeter with
NCV Detection. Please read this user’s manual carefully
and thoroughly before using the instrument.
The DMM550 is designed for use in an industrial setting
by HVAC/R contractors, building maintenance
technicians, MRO (maintenance, repair and operations)
personnel at process and power plants, electricians and
electrical/electronic technicians.
KEY FEATURES
• 18 functions, 48 ranges
• Measures AC/DC voltage, AC/DC current, resistance,
capacitance, frequency and duty cycle
• Also measures temperature from -58° to 1112°F
(-50° to 600°C) with included “K” type stem
thermocouple probe
• Checks continuity and diode integrity
• True RMS measurements
• IP54 water/oil/dust protection
• 6 ft. (1.8m) drop-resistant
• Designed to meet CAT III 1000V, CAT IV 600V safety
standard
• Auto or manual ranging
• Non-contact voltage (NCV) detection
• Backlit 3-1/2 digit (4,000 count) dual readout LCD
• 40-segment analog bar graph at bottom of LCD
• Hold, Max, Min, Rel (Zero) display options
• 15-minute Auto Power Off (can be disabled)
• 3 year limited warranty
3
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WHAT’S IN THE BOX
The meter is supplied inside an illustrated box. Also
inside the box are a set of 1000V/10A-rated double-
insulated test leads with screw-on alligator clips,
a “K” type stem thermocouple probe and plug adapter,
(1) “9V” battery, a cloth pouch with belt loop, and this
user’s manual.
PRODUCT OVERVIEW
Fig. 1 shows the labels and positions of the controls,
indicators and physical structures of the DMM550. Fig. 2
shows all possible indications on the LCD. Familiarize
yourself with the functions and meanings of these
controls, indicators and connectors before moving on to
the Setup Instructions and Operating Instructions.
Fig. 1. The controls,
indicators and
physical structures
of the DMM550.
햲Non-contact voltage (NCV) visual indication (red LED)
햳LCD
햴Function buttons:
•
REL ⌬: Multi-function button. Used to 1) Enter
relative measurement mode (see p. 10) and
2) Disable the meter’s Auto Power Off function
(see p. 11)
4
2
3
4
5
6
1
400
DMM550
NCV
TRMS
햸
햹
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• RANGE : Switches between Auto ranging and Manual
ranging modes (see p. 9)
• MAX/MIN : Enters Max/Min mode (see p. 10), in
which the secondary display shows the largest and
smallest values of any parameter since switching to
measure it.
• HOLD : “Freezes” the primary and secondary readouts
(but not the analog bar graph at the bottom of the
LCD)
• FUNC : Multi-function button. 1) With the rotary
function switch in the , , or position,
selects AC or DC voltage (see p. 13) or current
(see p. 12); 2) With the rotary function switch in the
Temp position, selects °F or °C unit (see p. 18);
3) With the rotary function switch in the position,
selects resistance measurement, continuity checking
or diode integrity verification (see pp. 15 – 16)
• Turns the backlight on and off
• NCV : Activates the non-contact voltage sensor
(see p. 14)
햵Rotary function switch
햶Input jacks:
uA/mA jack is used to measure currents
with amplitude <400mA;
10A jack is used to measure
currents with amplitude from 400mA to 10A
햷NCV sensor
햸Battery compartment (on back)
햹Flip-up stand (on back)
Fig. 2. All possible display indications
5
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SAFETY INSTRUCTIONS
 Warning 
To avoid possible electric shock or personal injury, and to
avoid damaging the meter or the equipment under test:
• Do not use the meter in any way not detailed in this
manual or the meter's safety features may be
compromised.
• Before using the meter, inspect the case.
Do not use the meter if it is damaged. Look for cracks
or missing plastic. Pay particular attention to the
insulation around the connectors.
• 
WARNING Inspect the test leads for damaged
insulation or exposed metal. Check the test leads for
continuity. Replace damaged test leads before using
the meter.
• Verify the meter’s operation by measuring a known
voltage. Do not use the meter if it operates abnormally.
Protection may be impaired. When in doubt, have the
meter serviced.
•  WARNING Do not apply more than the rated voltage,
as marked on the meter, between the and
COM
jacks or between any jack and ground. Also do not
input more than the rated current, as marked on the
meter, through the
10A or uA/mA jack.
• 
WARNING Do not measure voltages above 1000V in
Category III installations.
• 
WARNING Do not attempt to measure voltage with
the rotary function switch in the , , , ,
or
Temp position. Never attempt to measure current
with the rotary function switch in the , or
Temp
position.
• Use caution when working with voltages above
42VACRMS, or 60VDC. These voltages pose a shock
hazard.
• Use the proper terminals, function and range for all
measurements.
6
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•  WARNING Do not operate the meter around
explosive gas, vapor, or dust.
• 
WARNING When using the probes, keep your fingers
behind the finger guards. Do not touch the metal
probes of the test leads when making a measurement.
• When making connections, connect the black (–) test
lead before connecting the red (+) test lead; when
disconnecting, disconnect the red (+) test lead before
disconnecting the black (–) test lead.
• Disconnect circuit power and discharge all high-
voltage capacitors before measuring/testing resistance,
continuity, diodes, or capacitance.
• For all DC functions in both auto and manual ranging
mode, to avoid the risk of shock due to possible
improper reading verify the presence of any AC
voltages by first using the AC function. Then select a
DC voltage range equal to or greater than the AC range.
• Before measuring current, turn off power to the circuit
before connecting the meter.
• Do not operate the meter with the case (or part of the
case) removed.
• Use only (1) “9V” battery, properly installed in the
battery compartment, to power the meter. Do not use
rechargeable batteries.
• Replace the battery as soon as the low battery
indicator “ ” appears. Operated with a weak
battery, the meter might produce false readings that
could lead to electric shock and personal injury.
• Remove the test leads from the meter before opening
the meter case or battery compartment.
7
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Electrical Sy bols Used On the
Meter and In This Manual
Symbol Description Symbol Description
AC (Alternating Fuse
Current)
DC Double
(Direct Current) Insulated
Caution, risk of Risk of danger.
electric shock. Important
Hazardous information.
voltage. Refer to the
manual.
Battery
(Low battery) Earth ground
when shown
on display
Diode Continuity
Beeper
AC or DC ΩResistance
Capacitance Application and removal
from hazardous live
conductors permitted
For measurements
made on building
equipment such
as distribution
panels, feeders
and short branch
circuits, and on
lighting systems
in large buildings.
8
Auto Power Off
function enabled
CAT IV
For measurements on
circuits connected directly
to the source of power for a
given building (for example,
on the cable to the power
transformer ahead of a
building’s circuit breakers).
Very high levels of energy
available at CAT IV level
make arc flash possible.
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SETUP INSTRUCTIONS
INSTALL BATTERY
The battery compartment of the DMM550 is located at
the back of the meter.
To open the compartment, use a small Phillips-head
screwdriver to remove the single screw securing the
battery compartment cover/flip-up stand. Be careful not
to lose the small screw. Put the cover/stand to the side.
Plug the included “9V” battery into the wired socket
inside the compartment. The terminals of the battery and
the socket mate in only one way, with the smaller male
terminal plugging into the larger female terminal.
Secure the battery compartment by replacing the
cover/stand and reinstalling and tightening the Phillips-
head screw.
OPERATING INSTRUCTIONS
GENERAL INSTRUCTIONS
The DMM550 provides several functions that can be
applied to measurements and displays of multiple
parameters.
Ranging Options
By default, the meter automatically enters Auto Ranging
mode when powered on. In this mode, the meter chooses
the measurement range that maximizes the resolution of
its current, voltage, resistance, capacitance and
frequency measurements. The term indicates
operation in Auto Ranging mode.
To switch to Manual Ranging for any parameter other
than temperature, press the
RANGE button once. This will
make the term disappear and cause the meter to
enter the broadest full-scale range available for that
parameter (see the Specifications section beginning on
p. 18 for a list of the measurement ranges available for
each parameter).
Once the meter is in manual ranging mode, each
subsequent press of the
RANGE button reduces the full-
scale range by an order of magnitude (a factor of 10).
For example, pressing the
RANGE button with the meter
AUTO
AUTO
9
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operating in the 0 to 400μF full-scale manual range
reduces the full-scale range to 0 to 40μF (and improves
measurement resolution). The next press of the button
reduces the range to 0 to 4μF. When the smallest full-
scale range has been reached, the next press of the
RANGE button switches the meter back to the largest full-
scale manual range for the parameter being measured.
To exit Manual Ranging mode and return to Auto Ranging
mode, press and hold the
RANGE button.
Holding Readings
Pressing the HOLD button “freezes” the values on both
the primary and secondary readouts and causes an
icon to appear at the top left of the LCD. Pressing the
button again releases the hold and removes the icon.
While readings are held, the analog bar graph at the
bottom of the LCD continues to track real-time readings
of the parameter being measured.
Tracking Maximum and Minimum Readings
Pressing the MAX/MIN button once switches the
secondary readout to show the
largest value of the
parameter being measured since entering that
measurement mode. The primary display and the analog
bar graph at the bottom of the LCD will continue to show
real-time readings.
Pressing the
MAX/MIN button a second time switches the
secondary readout to show the
smallest value of the
parameter being measured since entering that
measurement mode. The primary display and the analog
bar graph at the bottom of the LCD will continue to show
real-time readings.
Pressing the
MAX/MIN button a third time resumes
“normal” display operation, with different values in the
primary and secondary readouts.
When the
MAX/MIN button is pressed, the meter will
automatically exit Auto Ranging mode and enter Manual
Ranging mode using the full-scale range in effect at that
moment.
Making Relative Measurements
Pressing the REL⌬ button during measurement of
current, voltage, resistance or capacitance freezes the
value being measured at that instant on the secondary
10
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(upper) readout. The term REL will appear at the upper
left of the LCD to indicate operation in this special mode.
In
REL mode, the primary (lower) readout shows the
difference between ongoing measurements and the
frozen value.
REL mode is useful for tracking changes in
dynamic processes or deviations from baseline readings.
When the
REL⌬ button is pressed, the meter
automatically exits Auto Ranging mode and enters
Manual Ranging mode using the full-scale range in effect
at that moment.
To exit
REL mode, press the REL⌬ button again.
Disabling Auto ower Off (A O)
By default, the meter automatically powers itself off if
no front-panel button is pressed within any span of
15 minutes. Fifteen seconds before the end of this
15-minute period, the meter announces that the APO
function is about to engage by sounding a sequence of
3 double beeps, followed by a long beep.
Once the APO function has activated and powered the
meter off, you can “wake the meter up” simply by turning
the rotary function switch to a different position.
The icon on the left side of the LCD indicates that the
APO function is enabled. To disable the APO function, you
must power on the meter in a special way—by pressing
and holding the
REL⌬ button while turning the rotary
function switch to any position other than
OFF . If the
meter is powered on in this way, the icon will not
appear. If the meter is left unattended with APO disabled,
it will remain powered on until its battery discharges
(typically, several days later).
Using the Analog Bar Graph
The bar graph at the bottom of the LCD (see below)
provides an analog representation of every measurement
shown in digital form on the primary readout above it.
The key feature of the bar graph is its fast response time.
It can reflect a change in a measured value 10 times
more quickly than the digital readout can. Accordingly, it
is useful for tracking parameters that change very rapidly
(a voltage or current, for example).
11
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Turning On the Backlight
Pressing the button turns on the LCD’s bright white
backlight, making measurements much easier to read in
dark spaces.
To prevent the backlight from draining the meter’s
battery, the backlight automatically extinguishes in
60 seconds.
MEASURING AC OR DC CURRENT
 Warning 
Do not attempt to measure: 1) currents larger than
400mA through the
uA/mA jack; 2) currents larger than
10A through the
10A jack continuously for more than
30 seconds; pause 1 minute after each measurement
of such a large current.
Remove power from the circuit to be tested and
discharge all capacitors.
(1) Turn the rotary function switch to the , or
position, depending on the current amplitude you
expect to encounter. If you are unsure what amplitude
to expect, select the position.
(2) Press the
FUNC button to select either AC or DC
current, as indicated by the or display icon on
the left side of the LCD.
(3) Before measuring DC currents, press the
REL⌬ button
to reset the DC current measurement baseline to
0A .
(4) Plug the black test lead into the black
COM jack at the
bottom right of the front panel.
(5) Plug the red test lead into the red
10A or uA/mA jack
at the bottom left of the front panel. Choose the
uA/mA jack if you have set the rotary function switch
to the or position and the
10A jack if you have
set the rotary function switch to the position.
(6) Break the circuit and connect the test leads across
the break. Connect the red lead to the higher-voltage
side of the break and the black lead to the lower-
voltage side.
(7) Re-apply power to the circuit and read the measured
current amplitude on the primary readout. If
O.L is the
DC
AC
12
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reading, the current amplitude exceeds the limit of the
selected current measurement mode. If this is the
case, move the rotary function switch to the next-
highest position among , and .
Notes:
A. During measurements of AC current, the primary
readout shows the amplitude of the current while the
secondary readout in the upper right corner shows the
frequency of the current.
B. eneral’s FX3000 Flex Clamp Adapter makes it
possible to enclose a thick or hard-to reach conductor,
a bundle of conductors, or a busbar carrying up to
3000A. The accessory uses induction to convert
current readings to millivolt values that can be
displayed by the DMM550. For more information or
to order, visit www.generaltools.com and enter
“FX3000” in the SEARCH box.
MEASURING AC OR DC VOLTAGE
 Warning 
Do not measure voltage higher than 600V. Doing so may
damage the meter’s internal circuitry. If the voltage is
over 1000V, the beeper will sound continuously,
indicating an over-range measurement.
(1) Turn the rotary function switch to the position. By
default, when the switch is initially set to this position
the meter is configured to measure DC voltage (as
indicated by the display icon on the left side of the
LCD). To measure AC voltage, press the
FUNC button
to change the icon to .
(2) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(3) Touch the black test lead to the lower-potential point
of the circuit under test, and the red test lead to the
higher-potential point.
(4) Read the measured voltage on the display. When
measuring DC voltage, if the test leads are reversed a
minus sign will appear at the left of the displayed value.
Note:
During measurements of AC voltage, the primary readout
shows the amplitude of the voltage while the secondary
AC
DC
13
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readout in the upper right corner shows the frequency of
the voltage.
Using the Non-contact Voltage Detector . The DMM550’s
NCV detector provides a safe (non-contact) way to check
whether a line, cable or AC outlet is “hot” (energized). At
the top of the meter (Fig. 1, Callout 6) is an NCV sensor
that can detect from a short distance the electromagnetic
field created by AC voltage. If voltage is detected, the
meter produces audible and visual alarms (a beeping
sound, and a flashing red light from an LED near the top
of the front panel (Fig. 1, Callout 1)).
Even unloaded AC circuits generate electromagnetic
fields. Although these fields are extremely weak, their
constantly changing nature means that they generate
some current. A sensitive NCV detector can sense this
current via induction, in much the same way that a
sensitive radio receiver can sense weak radio waves.
NCV detectors cannot detect DC voltages, such as those
present in automotive electrical systems. In addition, the
DMM550 typically cannot detect 120VAC from a distance
of more than 0.25 in. (6.2mm), and never through a wall
or metal conduit.
 Warning 
The NCV detector in the DMM550 is designed to indicate
the presence of AC voltage with an amplitude of
110VACRMS or greater. However,
do not assume that the
absence of a positive indication means that the circuit
under test is de-energized (not “hot”). Do not rely solely
on NCV detection to determine the presence of voltage in
a wire. NCV detection may be affected by the design of
the outlet, the type of wiring insulation and other
external factors. Also be aware that “false positive” NCV
indications may be triggered by connection of the meter’s
test leads to a voltage source or by external interference
from a flashlight, motor or other electrical device.
Whenever you have reason to suspect that a line or outlet
is “hot”, confirm your suspicion by measuring the voltage
of the line or outlet using the test leads with the meter’s
rotary function switch in the position.
14
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To check whether a line, cable or AC outlet is “hot”
(energized), touch it with the top of the meter or bring the
top within 1/4 inch of it while pressing and holding the
front-panel
NCV button. If the beeper sounds repeatedly
and the red LED flashes rapidly, the line or outlet is
energized.
The NCV detector works with the rotary function switch
in any position.
MEASURING RESISTANCE
 Warning 
To avoid electrical shock or damage to the meter when
measuring the resistance or checking the continuity of a
circuit, make sure power to the circuit is turned off and
all capacitors are discharged.
(1) Turn the rotary function switch to the position. By
default, when the switch is initially set to this position
with the test leads not plugged in the meter will
automatically 1) enter resistance measurement
(indicated by the term
MΩ at the lower right of the
LCD) and Auto Ranging modes and 2) display
O.L
(indicating an open circuit) on the primary readout.
(2) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(3) Measure the resistance by touching or clipping the
test leads to the desired test points of the circuit or to
the terminals of a component, as shown below.
(4) Read the measured resistance on the display. If the
measured resistance value is greater than 40MΩ,
O.L will appear on the primary readout. The meter
will take a few seconds to stabilize when measuring
resistances greater than 1MΩ.
15
RED TE T LEAD BLACK TE T LEAD
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16
CHECKING FOR CONTINUITY
(1) Turn the rotary function switch to the position.
Press the
FUNC button once to select the continuity
check function. Until the test leads are plugged in, the
primary readout will show
OL. , with the icon of a
continuity beeper ( ) above it.
(2) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(3) Touch or clip the test leads to any two points of the
circuit. The resistance between those two points will
be shown on the primary readout. If the resistance is
<50Ω, the beeper will sound continuously. If there is
no continuity (an open circuit or a resistance greater
than 600Ω between the two points),
O.L will appear
on the primary readout.
CHECKING THE INTEGRITY OF A DIODE
(1) Turn the rotary function switch to the position.
Press the
FUNC button twice to select the diode check
function. Until the test leads are plugged in, the
primary readout will show
.OL , with the icon of a
diode ( ) above it.
(2) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(3) Connect the red test lead to the anode (positive
terminal) of the diode to be tested and the black test
lead to its cathode (negative terminal), as shown
below.
(4) Read the diode’s forward bias voltage drop on the
display. A silicon diode typically has a forward bias
voltage of 0.7V. A germanium diode typically has a
forward bias voltage of 0.3V. A
0V reading in both
directions indicates a shorted diode. An
.OL reading
indicates an open diode. In either case, the diode is
defective and should be replaced.
RED TE T LEAD BLACK TE T LEAD
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MEASURING CAPACITANCE
To avoid possible damage to the meter or other
equipment, turn off the power source and discharge all
high-voltage capacitors.
(1) Disconnect the capacitor from power.
(2) Short the capacitor’s terminals to discharge it.
(3) Disconnect any resistors between the terminals of the
capacitor.
(4) Turn the rotary function switch to the position.
Until the test leads are plugged in, the primary
readout will show
0.000 nF .
(5) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(6) Connect the test leads to the terminals of the
capacitor.
(7) Read the measured capacitance on the display.
MEASURING FREQUENCY
AND DUTY CYCLE
As described earlier, the DMM550 automatically
measures the frequency of measured AC currents and
voltages and displays them on the secondary readout.
However, the range of frequencies that can be measured
and displayed in this way is limited to 10Hz to 1kHz.
Using the
Hz% position of the rotary function switch
expands the range of measurable frequencies to 10Hz to
40MHz, while providing better measurement resolution
(via multiple ranges) and greater measurement accuracy.
To measure frequency in this way:
(1) Turn the rotary function switch to the
Hz% position.
(2) Plug the black test lead into the front-panel
COM jack
and the red test lead into the jack.
(3) Touch or clip the test leads to the voltage source or
between loads.
(4) Read the measured frequency on the primary readout
and the duty cycle (as a percentage) on the secondary
readout.
17
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SPECIFICATIONS
arameter or Feature/Function Attribute
AC voltage (True RMS) Measurement ranges
Measurement accuracy
Overload protection
DC voltage Measurement ranges
Measurement accuracy
Overload protection
AC current (True RMS) Measurement ranges
Measurement accuracy
Overload protection
DC current Measurement ranges
Measurement accuracy
Overload protection
Resistance Measurement ranges
Measurement accuracy
Frequency (with rotary function Measurement ranges
switch in Hz% position)
Measurement accuracy
Overload protection
MEASURING TEMPERATURE
To measure the temperature of a solid, liquid or gas:
(1) Turn the rotary function switch to the
Temp position.
The primary readout will show spurious readings until
a thermocouple probe is plugged into the meter’s
front-panel jacks.
(2) Plug the included plug adapter into the red and black
jacks at the bottom front of the meter. Make sure to
insert the + (positive) plug of the adapter into the
jack and the
COM plug into the COM jack.
18
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Specification
0 to 400mV/4V/40V/400V/1000V
±(1.2% of reading + 5 digits) in 4V and 40V ranges;
±(1.5% of reading + 5 digits) in other ranges
250VACRMS in 400mV range; 1000VACRMS in other ranges
0 to 400mV/4V/40V/400V/1000V
±(0.8% of reading + 3 digits) in 400mV and 1000V ranges;
±(0.5% of reading + 5 digits) in other ranges
250VDCRMS in 400mV range; 1000VDCRMS in other ranges
0 to 400μA/4mA/40mA/400mA/10A
±(3% of reading + 5 digits) in 10A range; ±(1.5% of reading
+ 5 digits) in other ranges
600mA/1000V fuse with rotary function switch in or
position; 10A/1000V fuse with rotary function switch in
position
0 to 400μA/4mA/40mA/400mA/10A
±(2% of reading + 5 digits) in 10A range; ±(1% of reading
+ 5 digits) in other ranges
600mA/1000V fuse with rotary function switch in in or
position; 10A/1000V fuse with rotary function switch in
position
0 to 400Ω/4kΩ/40kΩ/400kΩ/4MΩ/40MΩ
±(1.5% of reading + 5 digits) in 40MΩ range;
±(0.8% of reading + 5 digits) in other ranges
10Hz to 40Hz/400Hz/4kHz/40kHz/400kHz/4MHz/40MHz
for 3V peak-to-peak AC inputs
±(1.5% of reading + 5 digits)
250VDC/VACRMS
19
(3) Plug the included “K” type thermocouple (or a
different “K” type thermocouple) into the adapter.
Make sure to insert the slightly wider blade of the
thermocouple into the – (negative) slot of the adapter.
(4) To measure a surface temperature, firmly attach the tip
of the thermocouple to the surface. To measure the
temperature of a liquid or gas (including ambient air),
make sure that the tip of thermocouple is within the fluid.
(5) Read the measured temperature on the primary
readout. Use the
FUNC button to toggle between
°F and °C units.
DMM550_Manual_RR1_FINAL_070914_awb 7/9/14 1:55 PM Page 19

arameter or Feature/Function Attribute
Frequency (with rotary function switch Measurement ranges
in position)
Measurement accuracy
Capacitance Measurement ranges
Measurement accuracy
Continuity Open circuit voltage
Threshold
Diode integrity Reverse DC voltage
Forward DC current
Duty cycle Measurement range
Measurement accuracy/
resolution
Temperature Measurement range
Measurement accuracy
(excluding thermocouple)
Overload protection level in resistance, frequency, continuity,
diode integrity and capacitance modes
Input impedance
Sampling time
Safety rating
Water/dust/oil protection level
Display No. of digits
Maximum count
Auto power off trigger
Operating temperature
Storage temperature
Maximum altitude
Power source
Dimensions
Weight (including battery)
20
Note: Accuracy values are stated for an operating temperature
between 64° and 82°F (18° and 28°C). All accuracy specifications
must be derated (increased) by 5.5% for each degree F of operating
temperature outside this range.
For example, an accuracy specification of ±3% between 64°F and
82°F would be derated to:
DMM550_Manual_RR1_FINAL_070914_awb 7/9/14 1:55 PM Page 20