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