Kusam-meco 2781 User manual

An ISO 9001:2008 Company
®
G-17, Bharat Industrial Estate, T. J. Road, Sewree (W), Mumbai - 400 015. INDIA.
Sales Direct.: 022 -24156638, Tel. : [phone], Fax : 022 - 24149659
Email : [email protected], Website : www.kusamelectrical.com
An ISO 9001:2008 Company
®
All Specifications are subject to change without prior notice
Chhaya Computer/D:/Chhaya/Coreldraw Files/New catlogs Dec 2011/2781-2781-T.cdr
1000A DC/AC DIGITAL CLAMP METER
9 FUNCTIONS 32 RANGES
Model 2781 / 2781-T(True RMS)
?Overload protection on all ranges.
?Maximum Voltage between any
terminal and earth ground 600V rms
?Dual slope integration
FEATURES :
GENERAL SPECIFICATIONS :
ïSensing : Average sensing (Model 2781)
True RMS sensing (Model 2781-T)
ïJaw opening size : cables f 40mm
ïDisplay : 3 ¾ digit 3999 counts liquid
crystal LCD display.
ïOver range indication : Display of “OL”
on LCD at the highest position means
range selection too low for the input.
(Except for ranges of 1000AAC, &
600V AC / DC)
ïPolarity : Symbol “-” automatic displayed
for negative input.
Æ
ACCESSORIES :
Test leads (pair), Battery installed, User’s manual, K-Type Thermocouople(model 2781-T) & Carrying case.
ELECTRICAL SPECIFICATIONS : 2781 / 2781-T
Accuracy are : ±(% of reading + number of digits) at 18°C to 28°C with relative humidity below 80%R.H.
?Data-hold facility
?DCA zero button for accurate reading
?Low battery indication
?Auto power off
RESISTANCE
Range Accuracy
Resolution
0.1 W
±(1.2%rdg+8dgts)
400 W1 W
10 W
100 W
±(1.0%rdg+2dgts)
4 KW
40 KW
400 KW
1 KW
10 KW
± (2%rdg+5dgts)
4 MW
40 MW
Overload Protection : 250V rms
0.001Hz
0.01 Hz
0.1 Hz
1 Hz
10 Hz
100 Hz
1 KHz
Unspecified
±(0.5%rdg+3dgts)
Unspecified
FREQUENCY
10Hz
100Hz
1KHz
10KHz
100KHz
1MHz
10MHz
Range Accuracy
Resolution
Over load protection : 250Vrms
Sensitivity : 1V
(2781only)
CAPACITANCE
Range Accuracy
Resolution
0.01nF
0.1 nF
1 nF
10 nF
10 nF
±(2.5%rdg+10dgts)
±(2.0%rdg+4dgts)
Unspecified
40 nF
400 nF
4 mF
40 mF
100 mF
Overload Protection : 250V rms
TEMPERATURE (2781-T)
Range Accuracy
Resolution
o
±(2.5%+3 C)
o o
-40 C~1000 C
o o
-40 F~1820 F o
±(2.5%+5 F)
o
1C
o
1F
Type-K thermocouple range & accuracy not specified
Supplied K-type thermocouple suitable for 250°C.
DIODE & CONTINUITY TEST
Display read approx. Forward
voltage of diode.
Accuracy ± (3.0%rdg+3)
If the resistance is less than 50W,
the beeper sounds continuously
Range Description
Overload Protection : 250V RMS
AC CURRENT
Range Accuracy
Resolution
Overload Protection : 1200A
10 mA
40 A
(2781-T) ± (2%rdg + 5dgts)
1 A
1000 A 0.1 A
400 A
ïSampling rate : 3 times per second (Digital display)
ïAuto power off : The meter is automatically powered off after idling
for 15 minutes. To awake the meter, turn the rotary function switch
or push any button.
ïOperating Temperature & Humidity : 0°C to 40°C; < 80% R.H.
Non-condensing
ïLow battery : The symbol “ ” is displayed when the batteries are
weak and below the operating Voltage. Replace batteries immidiately.
ïBattery life : Approx. 60 hrs continuously use with alkaline batteries.
ïPower supply : 1.5V AAA x 2
ïDimension : 228(L) x 76(W) x 39(H) mm
ïWeight : approx. 465gms. (Including batteries)
DC CURRENT
Range Accuracy
Resolution
Overload Protection : 1200A
10 mA
40 A
(2781-T) ± (2%rdg + 5dgts)
1 A
1000 A 0.1 A
400 A
Overload protection : 1200Vrms
Input Impedance : 10MW
DC VOLTAGE
Range Accuracy
Resolution
0.001 V
0.01 V
0.1 V
±(0.8%rdg+2dgts)
400 mV
(2781-T)
4 V
40 V
400 V
±(1.0%rdg+5dgts)
1 V
1000 V ±(1.0%rdg+2dgts)
0.1 mV
Overload protection : 660Vrms
Input Impedance : 10MW
Frequency Response : 40Hz ~ 450Hz for 400V & below,
40Hz ~ 100Hz for 750V
AC VOLTAGE
Range Accuracy
Resolution
0.001 V
0.01 V
0.1 V
±(1.0%rdg+5dgts)
400 mV
(2781-T)
4 V
40 V
400 V
±(1.8%rdg+5dgts)
1 V
750 V ±(1.5%rdg+5dgts)
0.1 mV
DUTY CYCLE
Range Accuracy
Resolution
0.1% ~ 99.9%

The waveforms on today’s AC power lines are anything but clean. Electronic equipment such as office computers, with their switching
power supplies, produce harmonics that distort power-line waveforms. These distortions make measuring AC voltage inaccurate
when you use an averaging DMM.
USE TRUE RMS WHEN MEASURING
AC WAVEFORMS
®
Average voltage measurements work fine when the signal you’re measuring is a pure sine wave, but errors mount as the waveform
distorts. By using true RMS measurements, however, you can measure the equivalent heating effect that a voltage produces,
including the heating effects of harmonics. Table 1 shows the difference between measurements taken on averaging DMMs & those
taken on true RMS DMMs. In each case, the measured signal’s peak-to-peak value is 2V. Therefore, the peak value is 1V.
For a 1-V peak sine wave, the average & RMS values are both 0.707V. But when the input signal is no longer a sine wave, differences
between the RMS values & the average readig values occur. Those errors are most prominent when you are measuring square waves
& pulse waveforms, which are rich in harmonics.
Table 1. Average versus true RMS comparison of typical waveforms.
Waveform Actual
Pk-Pk True RMS Reading Average Reading Reading Error
Sine Wave
Triangle Wave
Pulse (25% duty Cycle)
Pulse (6.25% duty Cycle)
Square Wave
Pulse (12.5% duty Cycle)
2.000 0.707 0.707 0%
2.000 0.577 0.555 -3.8%
2.000 1.000 1.111 +11.1%
2.000 0.433 0.416 -3.8%
2.000 0.331 0.243 -26.5%
2.000 0.242 0.130 -46.2%
One limitation to making true RMS measurements is crest factor, and you should consider crest factor when making AC measurements.
Crest factor is the ratio of a waveform’s peak (”crest”) voltage to its RMS voltage. Table 2 shows the crest factors for ideal waveforms.
Table 2. Crest factors of typical waveforms.
Waveform Crest Factor
DC
Sine Wave
Pulse (12.5% duty Cycle)
1.000
1.000
1.414
1.732
Square Wave
Triangle Wave
Pulse (25% duty Cycle)
Pulse (6.25% duty Cycle)
1.732
2.646
3.873
A DMM’s specifications should tell you the maximum crest factor that the meter can handle while maintaining its measurement
accuracy. True RMS meters can handle higher crest factors when a waveform’s RMS voltage is in the middle of the meter’s range
setting. Typically, a DMM may tolerate a crest factor of 3 near the top of its scale but it might handle a crest factor of 5 that’s in the
middle of the range. Therefore, if you’re measuring waveforms with high crest factors (greater than 3), you should adjust the DMM
so the measured voltage is closest to the center of the measurement range.
Another limitation of true RMS is speed. If you’re measuring relatively clean sine waves, then you can save time & money by using as
averaging DMM. True RMS meters cost more than averaging meters and can take longer to produce measurements, especially when
measuring millivolt-level AC signals. At those low levels, true RMS meters can take several seconds to stabilize a reading. Averaging
meters won’t leave you waiting.
D:/Chhaya/Coreldraw files/True RMS when measuring AC waveforms.cdr

Hz/DUTY
SELECT
1000
400
400
A
OFF
1000
A
~
V
V ~
W
RANGE
REL
CAP Hz
OFF
A
CLAMPMETER
2781
G-17, Bharat Industrial Estate,
T.J.Road, Sewree (W),
Mumbai - 400015. (INDIA)
Sales Direct : 24156638
Tel : [phone]
Fax : [phone]
Email : [email protected]
Website : www.kusamelectrical.com
Www.kusam-meco.co.in
Service Centre:
THIS WARRANTY IS BUYER’S SOLE AND
EXCLUSIVE REMEDY AND IS IN LIEU OF ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
“KUSAM-MECO” SHALL NOT BE LIABLE FOR
ANY SPECIAL, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM
ANY CAUSE WHATSOEVER.
All transaction are subject to Mumbai Jurisdiction.

Nearly every electrical engineer has a hand held
digital clamp meter (Tongtester). We sometimes take
them for granted, until we damage them or “burn them
out”. If you incorrectly connect your clamp meter to a
circuit, or if you have the clamp meter or wrong setting,
you damage the meter and possibly hurt yourself. You
can also get into trouble if you try to measure the
voltage across a changed capacitor.
Clamp meter users frequently burn their meters by
trying to measure current the same way as they
measure voltage. Remember, you measure voltage
across a circuit, and current through a circuit. When
you use the current input, your clamp meter becomes a
low impedance circuit element.
Even if you correctly insert your clamp meter in to
the circuit, you can still damage you meter. Don’t try to
measure current in excess of your meter’s capacity.
Check the current capacity of the Clamp meter.
If you are measuring current in industrial
environment. *you can easily exceed those ratings.
The best way to avoid damage is to use a clampmeter
with high current measuring capacity. To prevent
excess current from flowing through your meter, set
your meter to the correct function, say current, and its
highest range for the setting. If the reading is small,
change the range to the next lower range till the
reading can be read with the best possible accuracy.
When measuring voltage, connect the test leads
before your apply power to your circuit. To be safe,
start by setting your meter to its highest range first.
TAKE MEASUREMENT CAREFULLY AND YOU’LL
SPARE YOUR METER AND YOURSELF, SOME PAIN
Table of Contents
Title Page
Overview.....................................................1
Unpacking Inspection 2
Specifications
A. General Specifications 3
B. Electrical Specifications 4 to 6
AC Current
DC Current
AC Voltage
DC Voltage
Resistance
Capacitance
Frequency & Duty cycle
Diode / Continuity Test
Rules For Safe Operation 7 & 8
International Electrical Symbols 9
The Clamp Meter Structure 10
Display Symbols 12
Measurement Operation
A. AC Current Measurement 13
B. DC Current Measurement 14
C. AC Voltage Measurement 15
D. DC Voltage Measurement 17
E. Measuring Resistance 18
F. Capacitance Measurement 20
G. Frequency Measurement 21
H. Testing Diodes 22
I. Testing Continuity 24
Sleep Mode 25
Maintenance :-
A. General Service 25
B. Replacing the Battery 26
Test Certificate 27
Warranty
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......................................................28

Unpacking Inspection
Open the package case and take out the Clamp Meter
from the carrying case. Check the following items
carefully to see any missing or damaged part :
Item Description Qty.
1 English Operating Manual 1 piece
2 Test Lead 1 pair
In the event you find any Part missing or damaged,
please contact your dealer immediately.
2
Overview
Warning
To avoid electric shock or personal injury, read the
“Safety Information” and “Rules for Safe
Operation”carefully before using the Meter.
Digital Clampmeter Model - 278 (hereafter referred to
as “the Meter”) is a 3¾ digits Clampmeter with steady
operations, and highly reliable hand-held measuring
instrument having different measurement positions. The
Clampmeter not only can measure AC/DC Voltage,
AC/DC Current, Resistance, Capacitance, but also has
Diode Test, Frequency & duty cycle measurement & full
icon Display.
Terms in this manual
Warning : identifies conditions and
actions that could result in
serious injury or even
death to the user.
Caution : identifies conditions and
actions that could cause
damage or malfunction in
the instrument.
1
!
!
1

!Frequency Response : 40~65Hz
!Overload Protection : 1100A
Range Resolution Accuracy
400 A 0.1 A
1000 A 1 A ± (2%+5)
Range Resolution Accuracy
4 V 0.001 V
40 V 0.01 V
400 V 0.1 V
750 V 1 V
± (1.0%+5)
± (1.5%+5)
Range Resolution Accuracy
400 A 0.1 A
1000 A 1 A ± (2%+5)
·Overload Protection : 1100A
·Overload protection: 820V rms
·Input impedance : 10MW
·Frequency response : 40Hz~450Hz for 400V
and below.
40Hz~100Hz for 750V
AC Voltage (Auto ranging)
DC Current
Electrical Specifications
Accuracy : ±(% reading + digits)
Operating temperature : 23°C±5°C
Relative humidity : < 75% R.H.
AC Current
4
SPECIFICATIONS
GENERAL SPECIFICATIONS :
!Maximum voltage including transient overvoltage
between any terminals and grounding : 750Vrms.
!Display :3 digits
LCD forAccurate Reading.
!Auto Polarity Display
!Overloading :Display OL or -OL
!Battery Deficiency :Display “ ”
!Measurement Speed :Update 2.5 times/second.
!Measurement :When the conductor being
Deviation measured is not placed in
a correct position during
AC current measurement.
It will cause ±1% reading
deviation
!Max. Jaw Size :40 mm diameter.
!Power :2pcs of 1.5V battery (AAA)
!Auto Power Off : 15 minutes after the last
operation was made. To
turn ON the display, turn
the rotary switch to any
position or push any
button.
!Temperature :Operating 0°C`40°C (<80%
and humidity R.H.) Storage:- 0°C~60°C
(<80% R.H.)
!Dimensions (LxWxH):228mm X 76mm X 39mm
!Weight :Approximate 465g (battery
Included)
!Accessories :
¾ (3999 Counts)
Test Leads, Carrying Case,
Manual, Battery installed.
+ -
3

DC Voltage (Auto ranging)
Overload Protection : 1100V rms
Input impedance : 10MW.
Resistance (Auto Ranging)
Range Resolution Accuracy
4 V 0.001 V
40 V 0.01 V
400 V 0.1 V
1000 V 1 V
Range Resolution Accuracy
400 0.1 ±(1.2%+5)
4KW 1W
40KW 10W
400KW 100W
4MW 1KW
40MW 10KW
W W
±(0.8%+2)
±(1.0%+2)
±(1.0%+2)
±(2%+5)
Overload protection : 250Vrms
Range Resolution Accuracy
(50Hz?60Hz)
40nF 0.01 nF
400nF 0.1 nF
4mF 1 nF
40mF 10 nF
100mf 100 nF Unspecified
±(2.0%+4)
±(2.5%+10)
Overload Protection : 250V rms.
Capacitance (Auto Ranging)
5
Diode/Audible continuity
Overload protection : 250 Vrms
Display read approx. Forward
voltage of diode.
Accuracy : ±(3.0%rdg+3)
If the resistance is less than 50W, the
beeper sounds continuously
Range Description
Frequency & Duty Cycle (Auto Ranging)
Range Resol-
ution
Accuracy Overload
protection
10Hz 0.001Hz Unspecified
100Hz 0.01Hz
1KHz 0.1Hz
10KHz 1Hz
100KHz 10Hz
1MHz 100Hz
10MHz 1KHz Unspecified
DUTY Range : 0.1% to99.9%
Sensi-
tivity
±(0.5%+3) 1V 250Vrms
6

RULES FOR SAFE OPERATION (2)
!Disconnect circuit power and discharge all high-
voltage capacitors before testing resistance,
continuity, diodes, or current.
!Replace the battery as soon as the low battery
indicator appears. With a low battery, the
Meter might produce false readings that can
lead to electric shock and personal injury.
!Turn the Meter power off when it is not in use
and take out the battery when not using for a
long time.
!Constantly check the battery as it may leak
when it has not been used for some time,
replace the battery as soon as leaking
appears. A leaking battery will damage the
Meter.
8
To avoid possible electric shock or personal injury, and
to avoid possible damage to the Meter or to the
equipment under test, adhere to the following rules :
!Before using the Meter inspect the case. Do not
use the Meter if it is damaged or the case (or part
of the case) is removed. Look for cracks or missing
plastic. Pay attention to the insulation around the
connectors and Clamps.
!Inspect the test leads for damaged insulation or
exposed metal. Check the test leads for Continuity.
Replace damaged test leads with identical
electrical Specifications before using the Meter.
!Do not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and grounding.
!The rotary switch should be placed in the right
position and no any changeover of range shall be
made while measurement is conducted to prevent
damage of the Meter.
!When measurement is taken at an effective voltage
over 60V in DC or 30V rms in AC, special care
should be taken for there is danger of electric
shock.
!Use the proper terminals, function, and range for
your measurements.
!Do not use or store the Meter in an environment of
high temperature, humidity, explosive, inflammable
and strong magnetic field. The performance of the
Meter may deteriorate after the meter gets
dampened.
!When using the test leads, keep your fingers
behind the finger guards.
!
RULES FOR SAFE OPERATION
Warning
7

THE CLAMP METER STRUCTURE
1) SENSOR JAWS :
Pick up the current flowing through the
conductor.
2) Jaw Opening TheTrigger :
Press the trigger to open the jaw.
3) LCD display :
3 3/4 digital LCD with indications for
measurement values, unit symbol, decimal
point, polarity and low battery etc.
When switch at Wtest position, press
this button to select Wor or mode. When
switch at DCV, ACV test position, press this
button to select V or Hz or DUTY mode. When
switch at Hz test position, press this button to
select Hz or DUTY mode.
4) SELECT or Hz/DUTY button :
1
4
3
6
5
2
V
1000
+
DC/AC
CLAMP METER
2754
HOLD
PEAK
OFF
A
1000
600
400
1000
400
600
600
A
V
~
~
4KW
Hz
DCA ZERO
600V
600V
~ MAX CAT III
COM
+
A
9
78
2781
10
- +
~
AC (Alternating Current).
DC (Direct Current).
Both DC & AC.
Grounding.
Double Insulated.
Deficiency of Built-In Battery.
Continuity Test.
Diode.
Fuse.
Warning ! Refer to the Operating Manual.
Caution ! Risk of Electric Shock.
~
!
International Electrical Symbols
9

No. Symbol Meaning
1 AC Indicator for AC Voltage or Current.
2 DC Indicator for DC Voltage or Current
3 The battery is low.
Warning : To avoid false
readings, which could lead to
possible electric shock or
personal injury, replace the
battery as soon as the battery
indicator appears.
4 The Meter is in auto range mode in
which the Meter automatically
selects the range with the best
resolution.
5 Test of diode.
6 Data hold is active.
7 The continuity buzzer is on.
8 nf, mFThe unit of Capacitance
9W: Ohm. The unit of resistance.
3
KW: kilo-ohm. 1 x 10 or 1000 ohms.
6
MW: Megaohm. 1 x 10 or
1,00,000 ohms.
- +
Auto
H
W, KW, MW
DISPLAY SYMBOLS
Auto
- +
H
V/A
DC
AC
MKW
3999
14 OL The input value is too large for
the selected range.
13
12
Indicates negative reading.
A : Amperes (amps). The unit
of current.
V : Volts. The unit of voltage.
A
V
11
12
9) RANGE or REL button :
5) Data Hold button :
Press it once to hold the measured value and
store the value in memory. Press again to
release the hold fuction.
6) Rotary switch :
For selecting of desired range, and exiting
from auto-power off mode.
7) COM socket :
Connet to negative lead (black test lead) for
voltage, frequency, resistance, Capacitance,
diode testing.
8) "VWHz" socket :
Connect to positive lead (red test lead) for
voltage, frequency, resistance, Capacitance,
continuity, and diode measurement.
When switch at DCV, ACV or Wposition,
press this button to enter the manual range
mode. Keep this button for more than 2
seconds, return to auto-range state. When
switch at DCA position, push this button to set
the LCD reading to zero before measuring
DCA current.
11

MEASUREMENT OPERATION
A) AC Current Measurement
W
+
DC/AC CLAMP METER
2781
HOLD
Hz/DUTY
SELECT
OFF
A
1000
400
400
1000
A
~
V ~
Hz
RANGE
REL
600V
600V
~ MAX CAT III
COM
+
A
V
OFF
CAP
!Warning
To avoid electric shock, never measure current
while the test leads are inserted into the input
terminals and disconnect test leads and tested
circuit connection.
Never attempt an in-circuit current measure- ment
where the open-circuit voltage between the circuit
and the ground is greater than 60V
Use proper function and range for the measurement.
13
!
conductor at each time.
!When current measurement has been completed,
disconnect the connection between the conductor
under test and the jaw, and remove the conductor
away from the transformer jaw of the Meter.
!Place the switch in 1000A range if the measured
current is unknown.
To obtain accurate reading, measure only one
Caution
The measurement range of current are :
400A/ 1000A
To measure current, connect the meter as follows :
1. Set the function / range switch to the A
range.(400Aor 1000A)
2. Clamp the sensor jaw around one of the
conductors under test. Make sure that the clamp
jaw is perfectly closed.
3. Read the displayed value.
The measured value is shown on the display, it is
an effective value of sine wave (mean value
response).
B) DC Current Measurement
W
+
DC/AC CLAMP METER
2781
HOLD
Hz/DUTY
SELECT
OFF
A
1000
400
400
1000
A
~
V
~
Hz
RANGE REL
600V
600V
~ MAX CATIII
COM
+
A
V
OFF
CAP
14

!
Warning
Make certain that all test leads are disconnected
from the meter terminals.
1. Set the function / range switch to the A range.
(400A or 1000A)
2. Check that the display reads 00.01. If not, then
press the DCA Zero button to bring the display
reading to zero.
3. Clamp the sensor jaw around one of the
conductors under test. Make sure that the
clamp jaw is perfectly closed
4. Read the displayed value.
!
conductor at each time.
!When current measurement has been completed,
disconnect the connection between the conductor
under test and the jaw, and remove the conductor
away from the transformer jaw of the Meter.
!Place the switch in 1000A range if the measured
current is unknown.
To obtain accurate reading, measure only one
Caution
Red Black
~
+
C) AC Voltage Measurement
15
!If the display indicates " I " it is required to remove
the test leads from the circuit under test as the
selected range is overloaded.
To avoid harms to you or damages to the Meter
from electric shock, do not attempt to measure
voltage higher than 1000V DC & 750V AC although
readings may be obtained
To measure AC Voltage range are :
4V, 40V, 400V, 750V.
1. Set the function/range switch to the ~V range.
2. Connect the black and red test leads to the COM
and + terminals respectively.
3. Connect the test leads to the circuit being
measured and read the displayed value.
!
Warning
Caution
!In each range, the Meter has an input
impedance of 10 MW. This loading effect can
cause measurement errors in high impedance
circuits. If the circuit impedance is less than or
equal to 10kW, the error is negligible
(0.1 or less).
!When AC voltage measurement has been
completed, disconnect the connection between
the testing leads and the circuit under test and
remove testing leads from the input terminal.
16

E. Measuring Resistance
!
Red Black
+
!If the display indicates " I ", it is required to remove
the leads from the circuit under test as the
selected range is overloaded.
!In each range, the Meter has an input impedance
of 10MWThis loading effect can cause the
measurement errors in high impedance circuits.
If the circuit impedance is less than or equal to
10kW, the error is negligible (0.1 or less).
Caution
!When DC voltage measurement has been
completed, disconnect the connection between
the testing leads and the circuit under test and
remove testing leads from the input terminals.
To avoid damages to the Meter or to the devices
under test, disconnect circuit power and
discharge all the high-voltage capacitors before
measuring resistance.
Warning
18
To avoid harms to you or damages to the Meter from
electric shock, do not attempt to measure voltage
higher than 1000V AC& 750V DC, although reading
may be obtained.
The DC Voltage ranges is : 4V, 40V, 400V, 1000V
To measure DC Voltage, connect the Meter as
follows :
1. Set the function switch to the V range.
2. Connect the black and red test leads to the
COM and + terminals respectively.
3. Connect the test leads across with the object
being measured
The measured value is shown on the display.
!
~
Red Black
+
D) DC Voltage Measurement
WARNING
17

The resistance ranges are :
400.0W, 4.000kW, 40.00kW, 400kW, 4.000MWand
40.00MW
To measure resistance, connect the Meter as follows :
1. Insert the red test lead into the VW
and the black test lead into the COM terminal.
2. Set the rotary switch to W; resistance
measurement (W) is default or press SELECT
button to select resistance measurement mode.
3. Connect the test leads across with the resistance
being measured.
The measured value is shown on the display.
Note :
The test leads can add 0.1Wto 0.3Wof error to
resistance measurement.
To obtain precision reading in low-resistance, in 400W
range, short-circuit the input terminals before hand and
record the reading obtained (call this reading as x). (x) is
the additional resistance from the test lead. Then use
the equation.
Measured resistance value (y) - (x) = Precision reading
of resistance.
terminal
!For high-resistance measurement (>1MW), it is
normal for the meter to take several seconds
to obtain a stable reading.
!The LCD displays OL indicating open-circuit or
the tested resistor value is higher than the
maximum range of the meter.
!Resistance measurement is default to auto
range mode.
!Remove the objects being tested from the
circuit when measuring, to obtain more
accurate result.
19
The Capacitance function has 6 measurement
ranges : 4nF, 40nF, 400nF, 4mF, 40mF,100mF
To measure Capacitance connect the Meter
as follows :
!When resistance measurement has been
completed, disconnect the connection between
the testing leads and the circuit under test and
remove testing leads from the input terminals.
Using Resistance measurement function in a
live circuit will produce false results and may
damage the instrument. In many cases the
suspect component must be disconnected from
the circuit to obtain an accurate reading.
Caution
Never connect high voltage to the input sockets
with the switch in resistance range.
1)
2)
F. Capacitance measurement :
+
Red Black
To avoid damages to the Meter or to the equipment
under test, disconnect circuit power and discharge all
high-vol t age capaci t ors before m e asuring
capacitance. Use the DC voltage function to confirm
that the capacitor is discharged. Never attempt to
input over 60V in DC or 30V rms in AC to avoid
personal injury.
!
Warning
20

!
To avoid damages to the Meter or to the devices
under test, disconnect circuit power and
discharge all the high-voltage capacitors before
testing diodes.
Warning
H. Testing Diodes
Red Black
+
When the frequency signal to be tested is higher
than 30 V rms, the Meter cannot guarantee
accuracy of the measurement.
The frequency measurement range is upto 10MHz.
To measure frequency; connect the meter as follows :
1. Insert the red test lead into the VWterminal
and the black test lead into the COM
Terminal.
2. Set the rotary switch in the Hz range.
3. Connect the test leads across with the
object being measured.
The measured value is shown on the display.
Caution
When Hz me as urement ha s bee n
completed, disconnect the connection
between the testing leads and the circuit
under test.
22
Caution
Discharge capacitors before trying to measure it.
Set the meter in the capacitance range, using the
FUNCTION select button.
Insert the red test lead into the +terminal and
the black test lead into the COM terminal.
The measured value is displayed on the LCD.
·
·
·
·
·
·
sockets with the switch in Capacitance
range.
Using Capacitance measurement function
in a Live circuit will produce false results
and may damage the instrument. In many
cases the suspect component must be
disconnected from the circuit to obtain
an accurate reading.
Never connect high voltage to the Input
G) Frequency & Duty Cycle
V
1000
+
DC/AC
CLAMP METER
2781
HOLD
PEAK
OFF
A
1000
600
400
1000
400
600
600
A
V
~
~
4KW
Hz
DCA ZERO
600V
600V
~ MAX CATIII
COM
+
ARed Black
~
Warning :
To avoid harm to you or damages to the Meter,
do not attempt to measure voltages higher than
60V in DC or 30V rms in AC although reading
may be obtained.
!
21

Caution
!In a circuit, a good diode should still produce a
forward voltage drop reading of 0.5V to 0.8;
however, the reverse voltage drop reading
can vary depending on the resistance of the
pathways between the probe tips.
!Connect the test leads to the proper terminals
as said above to avoid error display.
!The LCD will display OL indicating either open
circuit or wrong polarity connection.
!The unit of diode is volt (V), displaying the
forward voltage drop readings.
!Remove the object being tested from the circuit
when measuring, to obtain a more accurate
result.
!When diode testing has been completed,
disc o nne c t the c o nnec tion b e twe e n the
testing leads and the circuit under test and
remove testing leads from the input terminals.
Use the diode test to check diodes, transistors and
other semiconductor devices. The diode test sends
a current through the semiconductor junction, then
measure the voltage drop across the junction. A
good silicon junction drops between 0.5V and 0.8V.
To test the diode out of a circuit, connect the
Meter as follows :
1. Connect red test lead to the "+" terminal and
black test lead to the "COM" terminal.
2. Set switch to the diode test position " ".
3. Connect the red test to the anode side and black
test lead to the cathode side of the diode being
tested.
4. Read forward voltage (V) value on display.
23
To test for continuity, connect the Meter as follows :
1. Insert the red test lead into the VW
terminal and the black test lead into the COM
terminal.
2. Set the rotary switch to Wand press
S E L E C T b u t t o n t o s e l e c t c o n t i n u i t y
measurement mode.
3. The buzzer sounds if the resistance of a
circuit under test is less than 50W.
Note
!The LCD displays OL indicating the circuit
being tested is open.
!When continuity testing has been completed,
disconnect the connection between the testing
leads and the circuit under test and remove
testing leads from input terminal.
I) Testing for continuity (see figure 10)
Warning
To avoid damages to the Meter or to the
devices under test, disconnect circuit power and
discharge all the high-voltage capacitors before
measuring continuity.
Red Black
+
24

To replace the battery :
1. Turn the Meter off and remove all the
connections from the input terminals.
2. Turn the Meter’s case top down.
3. Remove the screw from the bottom case,
and separate the bottom case from the
front case .
4. Remove the old battery from the battery
compartment.
5. Replace the battery with 2pcs of new 1.5V (AAA)
battery.
6. Rejo i n t h e c a s e b o t t o m a n d t h e f r o n t
case, and reinstall the screw.
!
Warning
- +
To avoid false readings, which could lead to
possible electric shock or personal injury, replace
t h e b a t t e r y a s s o o n a s t h e b a t t e r y
indicator “ ” appears.
Make sure the transformer jaw and the test leads
are disconnected from the circuit being tested
before opening the case bottom.
B. Replacing the Battery
26
!
Sleep Mode
To preserve battery life, the Meter automatically turns off
if you do not turn the rotary switch or press any button for
around 15 minutes.
The meter can be activated by turning the rotary switch
or pressing any button.
MAINTENANCE
This section provides basic maintenance information
including battery replacement instruction.
25
Do not attempt to repair or service your Meter
unless you are qualified to do so and have the
relevent calibration, performance test and service
information.
To avoid electrical shock or damage to the Meter, do
not get water inside the case.
A. General Service.
Warning
!Periodically wipe the case with a damp cloth and mild
detergent. Do not use abrasives or solvents.
!To clean the terminals with cotton bar with detergent
as dirt or moisture in the terminals can affect readings.
!Turn the Meter power off when it is not in use.
!Take out the battery when it is not using for a long
time.
!Do not use or store the Meter in a place of humidity,
high temperature, explosive, inflammable and strong
magnetic field.

27
MUMBAI
TEST CERTIFICATE
DIGITAL CLAMPMETER
This Test Certificate warrantees that
the product has been inspected and
tested in accordance with the published
specifications.
The instrument has been calibrated by
using equipment which has already
been calibrated to standards traceable
to national standards.
MODEL NO. ___________
KM 2781
SERIAL NO. ___________
DATE: ___________
ISO 9001
REGISTERED
QC
PASS
KUSAM-MECO
28
WARRANTY
Each “KUSAM-MECO” product is warranted to be free
from defects in material and workmanship under normal
use & service. The warranty period is one year (12
months) and begins from the date of despatch of goods.
In case any defect occurs in functioning of the
instrument, under proper use, within the warranty period,
the same will be rectified by us free of charges, provided
the to and fro freight charges are borne by you.
This warranty extends only to the original buyer or end-
user customer of a “KUSAM-MECO” authorized dealer.
This warranty does not apply for damaged Ic’s, fuses,
burnt PCB's, disposable batteries, carrying case, test
leads, or to any product which in “KUSAM-MECO’s”
opinion, has been misused, altered, neglected,
contaminated or damaged by accident or abnormal
conditions of operation or handling.
“KUSAM-MECO” authorized dealer shall extend this
warranty on new and unused products to end-user
customers only but have no authority to extend a greater
or different warranty on behalf of “KUSAM-MECO”.
“KUSAM-MECO’s” warranty obligation is limited, at
option, free of charge repair, or replacement of a
defective product which is returned to a “KUSAM-
MECO” authorized service center within the warranty
period.