MULTI MEASURING INSTRUMENTS M-270 User manual

AC/DC CURRENT
DIGITAL CLAMP-ON TESTER
M-270
INSTRUCTION MANUAL
Thank you very much for selecting our digital AC/DC clamp-on
Tester M-270.
This model is complex instrument and employ a very reliable
mechanical/electronic design.
Before you use your new instrument, read this Instruction
Manual completely and familiarize yourself thoroughly with
all functions.
Keep this manual carefully to take out whenever you need.
1. FEATURES
●Low cost high performance and True RMS reading AC/DC clamp-on tester.
●4000 count full scale display.
●Additional AC/DC voltage, resistance, frequency test, diode test and
continuity check.
●Data hold and auto power off function.
●Convenient push switch for auto zero adjustment for DC current measurement.

2. △
!WARNING
●Do not make measurements of power lines carrying more than 250V.
IN SOME CASES, POWER LINES MAY CARRY VOLTAGE SPIKES OF
SEVERAL TIMES OF THE NORMAL SUPPLY VOLTAGE. THIS INSTRUMENT
SHOULD NOT BE USED TO MEASURE POWER LINES.
*The term of “POWER LINE”means the electrical circuit providing the power to
factories, buildings, and etc.
●Before operating this instrument, familiarize yourself with all instructions
outlined in this manual.
●Always check to make sure that the function switch is set to the proper position.
●When making measurements, use CAUTION as dangerous voltages may be
present in normally safe areas.
●To avoid electrical shock, use CAUTION when working above 60V DC or 25V AC
rms.
Such voltages pose a shock hazard.
●Never make measurements with the case opened.
●Never fail to keep the maximum tolerable input.
●Never operate this instrument if it becomes wet, damp or has any liquid
condensation build-up on any part of the instrument.
●Never make measurements for uninsulated conductors or bus bars.
3. SPECIFICATIONS
AC conversion: AC coupled true rms reading
Crest factor: <3 (0~50% of the range) <2 (50~100% of the range)
Safety standard : Meets the requirements for double insulation to IEC 1010-2-032,
IEC 61010-1, IEC 61010-2-032 installation CategoryⅢ600V phase to earth.
E.M.C. standard : The instrument meets EN 61326-1/-2-2 and EN 61000-4-2/-3
Withstanding voltage : AC 5500V, 1 minute (between outer case and core of CT)
Measuring method : Dual integration mode
Jaw opening capability : 55mmφ
Display : 3 1/2 digit LCD max. reading of 3999 and annunciators
Over range indication : Blanking of all digits except MSD1 (except for AC/DC 600V
And AC/DC 2000A ranges)
Low battery indication : "B" mark on LCD readout
Sampling : 2 times/sec.
Data hold indication : "D･H" mark on LCD readout
Auto power off : The meter is set to power off mode approx. 10 minutes after the power
switch on.
Operating temperature : 0℃to 40℃, ＜80%RH (non-condensing)
Strange temperature :‐10℃to 60℃, ＜70%RH (non-condensing)
Power supply : 1.5V (“ AAA” size, R03) x2
Power consumption and battery life : Approx. 25mW, 90 hours continuous.
Size : 85(W)x240(H)x34(D)mm
Weight : Approx. 350g
Accessories : Carrying case…………..1
Instruction manual……1
Batteries…………………2
Test lead…………………1set

4. DIMENSIONS AND PANEL FUNCTION
①Current transducer(Jaw) 85
②Jaw opening lever
③Power switch
④Function switch
⑤Range switch
⑥Sub-function switch (--/~,Ω/･)))
⑦Zero adjustment switch
⑧Data hold switch 240
⑨LCD display
⑩Input terminal(V)(Hz)
⑪COM terminal
⑫Input terminal(Ω)( ｜)
⑬Battery cover
⑭Wrist strap
Measuring range (23℃±5℃, ＜80% RH ) :
Range/Resolution
Accuracy
Max. input
~A (50/60Hz)
… A
Manual range
40A/0.01A
±2.0% rdg±8 dgt
AC/DC 2000A
400A/0.1A
±1.5% rdg±8 dgt
2000A/1A
~V
(50/60Hz)
…V
Auto/manual
range
400mV/0.1mV
±1.2% rdg±5 dgt
AC/DC
600V rms
4V/0.001V
40V/0.01V
400V/0.1V
600V/1V
Hz
Frequency
Auto range
100Hz/0.01Hz
±0.5% rdg±3 dgt
AC/DC
600V rms
1000Hz/0.1Hz
10KHz/0.001KHz
100KHz/0.01KHz
1000KHz/0.1KHz
Resistance
400Ω/0.1Ω
±1.5% rdg±8 dgt
Input Protection
4KΩ/0.001KΩ
250V rms
40KΩ/0.01KΩ
400KΩ/0.1KΩ
4000KΩ/1KΩ
40MΩ/0.01MΩ
±3% rdg±10 dgt
･)))Continuity
check
400Ω/0.01Ω
Continuity beeper
＜Approx. 40Ω
250V rms
|
Diode test
2V
±10% rdg±3 dgt
250V rms

5. METHOD OF MEASUREMENT
5-1. Measurement of Current
5-1-1 Measurement of DC Current
①Set the power switch to "ON" position.
②Set the function switch to a range appropriate
to the current to be measured.
③Press the zero adjustment switch once, the zero
display will be observed.
Note: When pressing the zero adjustment switch in
DC 40A range, even if the zero display is not
obtained for high sensitivity, however,
this is not abnormal and the accuracy is kept
in the tolerance.
④Clamp the conductor of the circuit at the center of CT. Fig.1
⑤Read the current value in the display.
⑥If you make measurements in a dark place
or in a place where it is difficult to see the
readings, use the data hold switch.
Note : Clamp around only one conductor of the circuit to be measured. (See Fig.1)
Over range value is moved due to the zero adjustment, however, this is not
abnormal.
To release the zero adjustment mode, press the zero adjustment switch at least
1 second.
5-1-2 Measurement of AC Current
①Set the power switch to "ON" position.
②Set the function switch to a range appropriate to the current to be measured.
③Press the sub-function switch for AC measurement, “~” mark is displayed.
④Clamp the conductor of the circuit at the center of CT.
⑤Read the current value in the display.
⑥If you make measurements in a dark place or in a place where it is difficult to
see the readings, use the data hold switch.
Note : Clamp around only one conductor of the circuit to be measured. (See Fig.1)
When making the clamp measurements for high AC current, the noise sound
of CT may be caused, however, this is not abnormal.
△
!WARNING
●To avoid electrical shock or damage, the measurement is limited to the circuit
under 600V AC.
Such voltages pose a shock hazard.
●Never fail to keep the maximum 2000A input to avoid electrical shock or damage.
●Never make measurements for uninsulated conductors or bus bars.

5-2. Measurement of Voltage
5-2-1. Measurement of AC Voltage
Black Red +
①Set the power switch to "ON" position.
②Connect the plug of red test lead into
the “V”terminal and the plug of black
test lead into the “COM”terminal.
③Set the function switch to “~V”range.
The auto ranging mode is selected.
④Contact the tips of the test leads to the
circuit under test.
⑤Read the voltage value in the display.
Manual range mode: Fig. 2
Press the range switch to the manual range mode.
the instrument changes from the auto range to the manual ranging mode and
the range is held. Subsequent pressing of switch causes the up-and down-ranging
as below.
4V →40V →400V →600V →400mV↓
↑──────────────────
To return to the auto ranging mode, press the range switch at least one second.
5-2-2. Measurement of DC Voltage
①Set the power switch to "ON" position.
②Connect the plug of red test lead into the “V”terminal and the plug of black test
lead into the “COM”terminal.
③Set the range selector switch to “…V”range. The auto ranging mode is selected.
④Contact the tips of the test leads to the circuit under test.
⑤Read the voltage value in the display.
Manual range mode:
Press the range switch to select the manual range mode. The instruments changes
from the auto ranging to the manual ranging mode and the range is held.
Subsequent pressing of the switch caused the up- and down-ranging as below.
400mV →4V →40V →400V →600V ↓
↑───────────────────
To return to the auto ranging mode, press the range switch at least one second.
△
!WARNING
Do not make measurements of power lines carrying more than 250V.
IN SOME CASES, POWER LINES MAY CARRY VOLTAGE SPIKES OF
SEVERAL TIMES OF THE NORMAL SUPPLY VOLTAGE. THIS
INSTRUMENT SHOULD NOT BE USED TO MEASURE POWER LINES.
* The term of “POWER LINE”means the electrical circuit providing the
power to factories, buildings and etc.

△
!WARNING
POSSIBLE ELECTRICAL SHOCK. Do not make measurements if the case
is damaged or the rear case is removed. Remove all electrical inputs before
removing the rear case.
△
!WARNING
POSSIBLE ELECTRICAL SHOCK or FIRE HAZARD. Do not expose this
tester to rain or moisture. Do not operate the tester in the presence of
flammable gases or fumes.
△
!CAUTION
To avoid damage to the tester, disconnect test leads before changing
functions. Do not exceed the maximum input limits.
5-3. Measurement of Resistance and Continuity Check Red + Black
①Set the power switch to "ON" position.
②Connect the plug of red test lead into
the “Ω”terminal and the plug of black
test lead into the “COM”terminal.
③Set the function switch to “Ω”range.
The auto ranging mode is selected
④Contact the tips of the teat leads to the circuit under test.
⑤Read the resistance value in the display.
Fig.3
To select the continuity check, press the sub-function switch and “･)))” mark is displayed.
In the continuity check mode, if the circuit under test has a resistance of less than
approximately 40Ω, the continuity beeper will sound.
Manual range mode:
Press the range switch to select the manual range mode. The instruments changes
from the auto ranging to the manual ranging mode and the range is held.
Subsequent pressing of the switch caused the up- and down-ranging as below.
40MΩ→400Ω→4KΩ→40KΩ→400KΩ→4000KΩ↓
↑────────────────────────────
To return to the auto ranging mode, press the range switch at least one second.
△
!CAUTION
Be sure all voltage is turned OFF in the circuit before making resistance
measurement.

5-4. Measurement of Frequency (Hz)
①Set the power switch to “ON” position.
②Connect the plug of red test lead into the “Hz” terminal and the plug of black test
lead into the “COM” terminal.
③Set the function switch to “Hz” range. The auto ranging mode is selected and the
input sensitivity is set to 10mV.
④Press the range switch to select the input sensitivity.
Subsequent pressing of the switch changes the sensitivity as below
10mV →100mV →1V↓
↑───────────
⑤Contact the tips of the test leads to the circuit under test.
⑥Read the frequency value in the display.
△
!WARNING
Do not make measurements of power lines carrying more than 250V.
IN SOME CASES, POWER LINES MAY CARRY VOLTAGE SPIKES OF
SEVERAL TIMES OF THE NORMAL SUPPLY VOLTAGE. THIS
INSTRUMENT SHOULD NOT BE USED TO MEASURE POWER LINES.
* The term of “POWER LINE” means the electrical circuit providing the
power to factories, buildings and etc.
5-5. Measurement of Diode
①Set the power switch to "ON" position.
②Connect the plug of red test lead into the “｜”terminal and the plug of black
test lead into the “COM”terminal.
③Set the range selector switch to “｜”range.
④Contact the tips of the test leads to the diode under test.
(a)Forward voltage (b)Reverse Voltage
measurement measurement
Black Red Red Black
Fig. 4
As shown in Fig.4 (a), when measuring the forward voltage across the diode, a
normal diode will indicate 0.4 to 0.7V and, as shown in Fig.4 (b) the reverse voltage
will indicate a value near 3.000V. For a short-circuited diode, a value near 0mV will
be displayed.
△
!CAUTION
Be sure all voltage is turned OFF in the circuit before making diode test.

6. REPLACEMENT OF BATTERIES
When the battery voltage falls below a specified voltage value, the "B" mark will
appear in the display. If this occurs, replace the two batteries with new ones as
quickly as possible.
Turn the power switch to "OFF", prior
to installing batteries.
To install the batteries, remove the
battery cover located on the unit back.
Loosen the screw on the battery cover.
Replace the two batteries (UM-4 or
type AAA) with new ones, observing
polarity. Use high-quality batteries
which are guaranteed against leakage. OPEN
If the instrument is to be left unused
for long periods of time, to prevent
damage from leakage, remove the batteries. Battery Cover
△
!WARNING
POSSIBLE ELECTRICAL SHOCK AND FIRE HAZARD
Do not replace the batteries, clamping CT to the conductor or during voltage
measurement.
Do not use the instrument keeping battery cover off.
7. REPAIR SERVICE
When making requests for repair service, please bring the instrument directly to the
dealer. If this is impossible, however, send the instrument directly to our sales office.
When mailing this instrument, always pack it in its original or equivalent packing
material and pack together with name, address, telephone number and the warranty
documentation.
●To ensure speedy and reliable repair, always include information as the type of
failure and cause.
●If required, always return accessories with the instrument.
●When contacting us, provide the model number and serial number of your
instrument.
8. WARRANTY
This instrument is sent out from our factory after the sufficient internal inspections
but if you find any defect due to the fault in our workmanship or the original parts,
please contact the dealer where you bought the instrument.
The warranty period is 12 months from the date of purchase and the instrument
shall be repaired at free of charge, provided that we judge the cause of defect is
obviously resulted from our responsibility.
MULTI MEASURING INSTRUMENTS CO.,LTD.
Akihabara Murai Bldg. 7F, 1-26 Kanda Sakuma-cho,
Chiyoda-ku, Tokyo, Japan, 101-0025
TEL : [phone] FAX : [phone]
Home Page : http://www.mutimic.com/
E-mail : [e-mail]