ATP Instrumentation DM-921 User manual

10A μ
COM
every
15 min.
MAX
¦¸
V
AUTO
Ω
V
V
Mode
DC
AC
CF
μ
Range
MAX CF
OPERATING INSTRUCTION
AUTORANGINGMULTIMETER

1
SAFETY INFORMATION
The following safety information must be observed to insure
maximum personal safety during the operation at this meter:
Do not use the meter if the meter or test leads look damaged,
or if you suspect that the meter is not operating properly.
Never ground yourself when taking electrical measurements.
Do not touch exposed metal pipes, outlets, fixtures, etc.,
which might be at ground potential. Keep your body isolated
from ground by using dry clothing, rubber shoes, rubber mats,
or any approved insulating material.
Turn off power to the circuit under test before cutting,
unsoldering, or breaking the circuit. Small amounts of current
can be dangerous.
Use caution when working above 60V dc or 30V ac rms.
such voltages pose a shock hazard.
When using the probes, keep your fingers behind the finger
guards on the probes.
Measuring voltage which exceeds the limits of the multimeter
may damage the meter and expose the operator to a shock
hazard. Always recognize the meter voltage limits as stated

2
on the front of the meter.
Never apply voltage or current to the meter that exceeds the
specified maximum:
SAFETY SYMBOLS
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) 500 VAC or VDC.
WARNING
CAUTION
MAX
500V

3
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.
CONTROLS AND JACKS
1. 2000 count Liquid Crystal Display with symbolic signs
2. Function switch
3. Positive input jack
Input Limits
Function
Maximum Input
V DC or V AC
CATII-1000V DC /AC
CATIII-600V DC /AC
mA DC/AC
200mA DC/AC
A DC/AC
10A DC/AC (30 seconds max
every 15 minutes)
Resistance, Diode test,
Continuity
Temperature
500V DC/AC

4
2
4
10A
53
μ
COM
every
15 min.
MAX
¦¸
V
AUTO
Ω
7
V
V
6Mode
1DC
AC
8
CF
μ
9
Range
MAX CF
4. COM (negative) input jack
5. 10A (positive) input jack for 10A DC or AC measurements
6. Mode pushbutton: selection Continuity/Diode, AC/DC,
Temperature(C/F)
7. Range pushbutton
8. Data Hold pushbutton
9. MAX. Hold pushbutton

5
SYMBOLS AND ANNUNCIATORS
Continuity
BAT Low Battery
Diode
DATA HOLD Data Hold
AUTO AutoRanging
AC Alternating Current or Voltage
DC Direct Current or Voltage
SPECIFICATIONS
The instrument complies with: EN61010-1.
Insulation: Class2, Double insulation.
Overvoltage category: CATIII 600V, CATII 1000V.
Display: 2000 counts LCD display with function indication.
Polarity: Automatic, (-) negative polarity indication.
Overrange: “OL” mark indication.
Low battery indication: The “BAT” is displayed when the
battery voltage drops below the operating level.
Measurement rate: 2 times per second, nominal.
Auto power off: Meter automatically shuts down after approx. 15
minutes of inactivity.

6
Operating environment: 0 oC to 50 oC (32
o
F to 122
o
F) at <
70 % relative humidity.
Storage temperature: -20 oC to 60 oC (-4
o
F to 140
o
F) at < 80 %
relative humidity.
For inside use, max height: 2000m
Pollution degree: 2
Power: One 9V battery , NEDA 1604, IEC 6F22.
Dimensions: 150 (H) x 70 (W) x 48 (D) mm
Weight: Approx.: 255g.
Accuracy is given at 18 oC to 28 oC (65
o
F to 83
o
F), less than
70 % RH
DC Voltage (Auto-ranging)
Range
Resolution
Accuracy
200.0mV
0.1mV
+0.5% of rdg + 2 dgts
2.000V
1mV
+1.2% of rdg + 2 dgts
20.00V
10mV
200.0V
100mV
600V(CATIII)
1V
+1.5% of rdg + 2 dgts
1000V(CATII)
+1.5% of rdg + 4 dgts
Input Impedance: 10M.
Maximum Input: 600V dc/ac rms.(CATIII)
Maximum Input: 1000V dc/ac rms.(CATII)

7
AC Voltage (Auto-ranging except 200mV)
Range
Resolution
Accuracy
200.0mV
0.1mV
+1.5%of rdg + 30 dgts
2.000V
1mV
+1.2% of rdg + 3 dgts
20.00V
10mV
+1.5% of rdg + 3 dgts
200.0V
100mV
600V(CATIII)
1V
+2.0% of rdg + 4 dgts
1000V(CATII)
+2.0% of rdg + 8 dgts
Input Impedance: 10M.
Frequency Range:50 to 60Hz
Maximum Input: 600V dc/ac rms.(CATIII)
Maximum Input: 1000V dc/ac rms.(CATII)
DC Current (Auto-ranging for uA and mA)
Range
Resolution
Accuracy
200.0uA
0.1uA
+1.0% of rdg + 3 dgts
2000uA
1uA
+1.5% of rdg + 3 dgts
20.00mA
10uA
200.0mA
100uA
10A
10mA
+2.5% of rdg + 5 dgts
Overload Protection: 0.2A / 250V and 10A / 250V Fuse.
Maximum Input: 200mA dc or 200mA ac rms on uA / mA ranges,
10A dc or ac rms on 10A range.
AC Current (Auto-ranging for uA and mA)

8
Range
Resolution
Accuracy
200.0uA
0.1uA
+1.5% of rdg + 5 dgts
2000uA
1uA
+1.8% of rdg + 5 dgts
20.00mA
10uA
200.0mA
100uA
10A
10mA
+3.0% of rdg + 7 dgts
Overload Protection: 0.2A / 250V and 10A / 250V Fuse.
Frequency Range: 50 to 60 Hz
Maximum Input: 200mA dc or 200mA ac rms on uA / mA ranges,
10A dc or ac rms on 10A range.
Clamp-onAdaptors DC Current
Range
Resolution
Accuracy
200A
0.1A
+1.0% of rdg +3dgts
(meter only, Clamp-on
Adaptor accuracy not
included)
2000A
1A
Sensor: Clamp-on Adaptor (Note: not provide)
200A Range Input Sensitivity: 1mV/A
2000A Range Input Sensitivity: 1mV/A
Overload protection: 500V dc or ac rms..
Clamp –onAdaptorAC Current
Range
Resolution
Accuracy

9
200A
0.1A
+1.5% of rdg +3dgts
(meter only, Clamp-on
Adaptor accuracy not
included)
2000A
1A
Sensor: Clamp-on Adaptor (Note: not provide)
200A Range Input Sensitivity: 1mV/A
2000A Range Input Sensitivity: 1mV/A
Frequency Range: 50 to 60 Hz
Overload protection: 500V dc or ac rms..
Resistance (Auto-ranging)
Range
Resolution
Accuracy
200.0
0.1
+1.2% of rdg + 4 dgts
2.000k
1
+1.0% of rdg + 2 dgts
20.00k
10
+1.2% of rdg + 2 dgts
200.0k
100
2.000M
1k
20.00M
10k
+2.0% of rdg + 3 dgts
Input Protection: 500V dc or 500V ac rms.
Temperature
Range
Resolution
Accuracy
-50
o
C~+1000
o
C
1
o
C
+3% of rdg +5dgts
-58
o
F~+1832
o
F
1
o
F
+3% of rdg +8dgts
Sensor: Type K Thermocouple
Overload protection: 500V dc or ac rms..

10
Diode Test
Test current
Resolution
Accuracy
0.3mA
typical
1 mV
+10% of rdg + 5 dgts
Open circuit voltage: 1.5V dc typical
Overload protection: 500V dc or ac rms.
Audible continuity
Audible threshold: Less than100 Test current: <0.3mA
Overload protection: 500V dc or ac rms.
OPERATION
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. This meter has Auto OFF that
automatically shuts the meter OFF if 15 minutes elapse between
uses.
2. If “OL”appears in the display during a measurement, the

11
value exceeds the range you have selected. Change to a higher
range.
NOTE: On some low AC and DC voltage ranges, with the test leads not
connected to a device, the display may show a random, changing reading.
This is normal and is caused by the high-input sensitivity. The reading will
stabilize and give a proper measurement when connected to a circuit.
MODE BUTTON
To select Diode/Continuity or DC/AC voltage,
current,Temperature(C/F)
RANGE BUTTON
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 button. The “AUTO” display indicator will turn off.
2. Press the RANGE button to step through the available ranges until
you select the range you want.
3. Press and hold the RANGE button for 2 seconds to
exit the ManualRanging mode and return toAutoRanging.

12
DATA HOLD BUTTON
The Data Hold function allows the meter to "freeze" a measurement for
later reference.
1. Press the DATA HOLD button to “freeze” the reading on the
indicator. The indicator “HOLD” will be appear in the display.
2. Press the DATA HOLD button to return to normal operation.
MAX HOLD BUTTON
The max. Hold position is used to measure the maximum value.
The maximum measured value is up dated continuously. Press
once again the button, will release the hold and allow a further
measurement.
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 V DC position (“mV”will appear in the
display).
2. Insert the black test lead banana plug into the negative (COM) jack
and the red test lead banana plug into the positive (V) jack.
3. Touch the test probe tips to the circuit under test. Be sure to observe

13
the correct polarity (red lead to positive, black lead to negative).
4. Read the voltage in the display. The display will indicate the
proper decimal point and value. If the polarity is reversed, the
display will show (-) minus before the value.
AC VOLTAGE 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 V AC position.
2. Insert the black test lead banana plug into the negative (COM)
jack and the red test lead banana plug into the positive (V)
jack.
3. Touch the test probe tips to the circuit under test.

14
4. Read the voltage in the display. The display will indicate the
proper decimal point, value and symbol (AC, V, etc.).
DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 10A scale
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 2000A DC, set the function switch to
the A position and insert the red test lead banana plug into the (A)
jack.
3. For current measurements up to 200mA DC, set the function switch to
the mA range and insert the red test lead banana plug into the (mA)
jack.
4. For current measurements up to 10A DC, set the function switch to the
A position and insert the red test lead banana plug into the 10A jack.
5. Press the AC/DC button until “DC” appears in 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.

15
8. Apply power to the circuit.
9. Read the current in the display. The display will indicate the proper
decimal point, value and symbol.
AC CURRENT MEASUREMENTS
WARNING: To avoid electric shock, do not measure AC current on
any circuit whose voltage exceeds 250VAC.
CAUTION: Do not make current measurements on the 10A scale
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 2000A AC, set the function switch to
the A position and insert the red test lead banana plug into the (A)
jack.
3. For current measurements up to 200mA AC, set the function switch to
the mA range and insert the red test lead banana plug into the (mA)
jack.
4. For current measurements up to 10A AC, set the function switch to the
A position and insert the red test lead banana plug into the 10A jack.
5. Press the AC/DC button until “AC” appears in the display.
6. Remove power from the circuit under test, then open up the circuit at

16
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 in the display. The display will indicate the
proper decimal point, value and symbol.
CLAMP–ON ADAPTOR AC/DC CURRENT
MEASUREMENTS
1. Set the function switch to the A DC/AC (clamp–on adaptor) position
2. Insert the clamp–on adaptor black test lead banana plug into the
negative (COM) jack and the red test lead banana plug into the
positive (V) jack.
3. Press the MODE button until “AC/DC” appears in the display.
4. Press the trigger to open jaw. Fully enclose one conductor to be measured.
5. Read the AC/DC current in the display.
NOTE: The output analog signal Sensitivity of The AC/DC CLAMP–ON
ADAPTOR is 1mV/A

17
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 position.
2. Insert the black test lead banana plug into the negative (COM) jack
and the red test lead banana plug into the positive jack.
3. 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.
4. Read the resistance in the display. The display will indicate the proper
decimal point, value and symbol.
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 position.
2. Insert the black lead banana plug into the negative (-) jack (COM)
and the red test lead banana plug into the positive (+) jack ().
3. Press the button until the symbol appears in the display.
4. Touch the test probe tips to the circuit or wire you wish to check.

18
5. If the resistance is less than approximately 30, the audible signal
will sound. The display will also show the actual resistance.
DIODE TEST
WARNING: To avoid electric shock, do not test any diode that has
voltage on it.
1. Set the function switch to position.
2. Press the button until the symbol appears in the display.
3. Insert the black test lead banana plug into the negative (-) jack (COM)
and the red test lead banana plug into the positive (+) jack ().
4. Touch the test probe tips to the diode or semiconductor junction you
wish to test. Note the meter reading
5. Reverse the probe polarity by switching probe position. Note this
reading.
6. The diode or junction can be evaluated as follows:
A. If one reading shows a value and the other reading shows OL, the
diode is good.
B. If both readings show OL, the device is open.
C. If both readings are very small or 0, the device is shorted.
NOTE: The value indicated in the display during the diode check is the
forward voltage.

19
TEMPERATURE MEASUREMENTS
WARNING: To avoid electric shock, disconnect both test probes from
any source of voltage before making a temperature measurement.
1. If you wish to measure temperature in oF, set the function switch to
the oF range. If you wish to measure temperature in oC, set the
function switch to the oC range.
2 Insert the black test lead banana plug into the negative (COM) jack and
the red test lead banana plug into the positive (V) jack, making sure to
observe the correct polarity.
3. 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).
4. Read the temperature in the display. The digital reading will indicate
the proper decimal point and value.
WARNING: To avoid electric shock, be sure the thermocouple has
been removed before changing to another measurement function.
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