YOKOGAWA CL255 User manual

IM CL255
2018.6 12 版 (KYOU)
IM CL255
User's
Manual
保証書付
CL255
Clamp-on Tester
クランプテスタ

Contents
■PrecautionsforSafetyUseoftheInstrument･････････････ ⅰ
1．InstrumentLayout････････････････････････････････････ 1
2．Measurement････････････････････････････････････････ 4
2.1PreparationforMeasurement････････････････････ 4
2.2DCCurrentMeasurement･･･････････････････････ 4
2.3ACCurrentMeasurement････････････････････････ 5
2.4DCVoltageMeasurement･･･････････････････････ 6
2.5ACVoltageMeasurement･･･････････････････････ 7
2.6ResistanceMeasurement････････････････････････ 8
2.7ContinuityCheck(400Ωrangefixed)･････････････ 8
2.8FrequencyMeasurement････････････････････････ 9
2.9PeakMeasurement････････････････････････････ 10
2.10AverageMeasurement ･････････････････････････ 11
3．OtherFunctions･････････････････････････････････････ 12
3.1SleepFunction････････････････････････････････ 12
3.2DataHoldFunction････････････････････････････ 12
3.3LoHzFunction････････････････････････････････ 12
3.4OUTPUTTerminal(Forcurrentrangesonly)･･････ 13
3.5OptionalAccessories･･････････････････････････ 14
4．BatteryReplacement･････････････････････････････････ 15
5．Specifications･･･････････････････････････････････････ 16
6．CalibrationandAfter-salesService････････････････････ 20

IM CL255 i
■ Precautions for Safe Use of the Instrument
Whenhandlingtheinstrument,ALWAYSobserveallofthecautionarynoteson
safetygivenbelow.YokogawaM&CCorporationisnotatallliablefordamage
resulting from misuse of this product by the user that is contrary to these
cautionarynotes.
Varioussymbolsareusedon the instrument and in thismanualtoensurethe
product is used safety and to protect operators and property from possible
hazards or damage. The following safety symbols are used where appropri-
ate.Readtheexplanationscarefullyandfamiliarizeyourselfwiththesym-bols
beforereadingthetext.
Theinstrumentandthismanualusethefollowingsafetysymbols:
Danger!HandlewithCare.
Thissymbolindicates that theoperatormust refer to anexplanationin
theUsersManualinordertoavoidtheriskofpersonalinjuryordeath
and/ordamagetotheinstrument.
DoubleInsulation
Thissymbolindicatesdoubleinsulation.
ACVoltage/Current
ThissymbolindicatesACvoltageorcurrent.
DCVoltage/Current
ThissymbolindicatesDCvoltageorcurrent.
AC/DCVoltage/Current
ThissymbolindicatesAC/DCvoltageorcurrent.
Ground
Thissymbolindicatesground(earth)
ndicatesthatthisinstrumentcanclamponbareconductors when
measuring avoltagecorresponding totheapplicable Measurement
category,whichismarkednexttothissymbol.
WARNING

Indicates that there is a possibility of serious personal injury or loss of
lifeiftheoperatingprocedure is not followed correctlyanddescribesthe
precau-tionsforavoidingsuchinjuryorlossoflife.
CAUTION
 Indicates that there is a possibility of serious personal injury of damage
to the instrument if the operating procedure is not followed correctly and
de-scribestheprecautionsforavoidingsuchinjuryordamage.

ii IM CL255
NOTE
Drawsattentiontoinformationessentialforunderstandingtheoperationand
features.
WARNING
●Nevermakemeasurementonacircuitabove750VACor1000VDC.
●Do not use the instrument in an atmosphere where any flammable or
ex-plosivegasispresent.
●Do not attempt to make measurement in the presence of flammable
gas-ses,fumes,vaporordust.Otherwise,theuseoftheinstrumentmay
causesparking,whichcanleadtoanexplosion.
●Avoidusingtheinstrumentifithasbeenexposedtorainormoistureor
ifyourhandsarewet.
●DonotexceedthemaximumallowabIeinputofanymeasurementrange.
●Neveropenthebatterycompartmentcoverwhenmakingmeasurement.
●Donotusetheinstrumentifthereisanydamagetothecasingorwhen
thecasingisremoved.
●DonotturntheFunctionSelectorswitchwithpluggedintestleadscon-
nectedtothecircuitundertest.
●Donotinstallsubstitutepartsormakeanymodificationtothe
instrument.ReturntheinstrumenttoYokogawaMeters&Instrumentsor
yourdistributorforrepairorre-calibration.
●Alwaysswitchofftheinstrumentbeforeopeningthebattery
compartmentcoverforbatteryreplacement.
●Donotusethetestleadsthathavedeterioratedoraredetective.
●Checkthetestleadscontinuity
WARNING

Toavoiddamagetotheinstrumentorelectricshock!
TherestrictionsonthemaximumvoltagelevelforwhichtheCL255testers
can be used, depend on the measurement categories specified by the
safety standards. These category specifications are formulated to protect
operatorsagainsttransientimpulsevoltageinpowerlines.
Function
MaximumAllowableInput
MEASUREMENT
CATEGORYII MEASUREMENT CATEGORYIII
A, A
AC2000Arms
Measuringcircuitvoltage:
AC750Vrms
DC1000V
AC2000Arms
Measuringcircuitvoltage:
AC600Vrms
DC600V
V, V AC750Vrms/DC1000V
AC600Vrms/DC600V
Inputterminal-to-
groundvoltage
AC750Vrms/DC1000V

IM CL255 iii
O(None,Other)
OthercircuitsthatarenotdirectlyconnectedtoMEAINS.
MeasurementcategoryII(CAT.II)
Local level, appliance, portable equipment etc., with smaller transient
over-voltagesthanCAT.III.
MeasurementcategoryIII(CAT.III):
Distribution level, fixed installation, with smaller transient over-voltages
thanCAT.IV.
CAUTION
● Always make sure to insert each plug of the test leads fully into the
ap-propriateterminalontheinstrument.
●Makesuretoremovethetestleadsfromtheinstrumentbeforemaking
currentmeasurement.
●BesuretosettheFunctionSelectorswitchtothe"OFF"positionafter
use. When the instrument will not be in use for a long period of time,
Placeitinstorageafterremovingthebattery.
●Useadampclothanddetergentforcleaningtheinstrument.Donotuse
abrasivesorsolvents.
NOTE
●RadiationimmunityaffectstheaccuracyofCL255testersunderthecon-
ditionsspecifiedinEN61000-4-3.
●If equipment generating strong electromagnetic interference is located
nearly,thetestersmaymalfunction.

IM CL255 1
1. Instrument Layout
(1)TransformerJaws:Pickupcurrentflowingthroughtheconductor.
(2)Open/Close Lever : Operates the transformer jaws. Press to open the
TransformerJaws.
(3)Function Selector Switch : Selects function to use. Also switches off
theinstrumentwhensetto"OFF"position.
(4)DataHoldButton:Freezesthedisplayreading." "isshownonthe
displaywhenDataHoldisenabled.
Note : When the plug is inserted into the output terminal, Data Hold
Switch operates as range selection switch. (See section 3.4 OUTPUT
Terminal)
(5) ModeSelectorButton:Selectsmeasuringmode.Theinstrument
defaults to the normal mode (NOR) Then, press this switch to cycle
through measuring modes. In any mode, pressing this switch for more
thanonesecondreturnstheinstrumenttothenormalmode.

2 IM CL255
(6) Button:UsedforzeroadjustmentonDCAandresistanceranges.
Also used to reset the display reading in the PEAK mode. On DCA
range," "isshownonthedisplaywhenauto-zeroingiscompleted.
(Au-to-zeroingisavailableon400Arangeonly.)
(7)LCDDisplay : Fieldeffect type ofliquidcrystal display withmaximum
counts of 3999. Function symbols and decimal point are controlled by
themicroprocessorbasedontheselectedfunctionandmeasuringmode.
(8)TerminalCover:SlidesoverHiandLoTerminalstopreventaccessto
themwhenOUTPUTterminalisinuse.
(9)OUTPUT Terminal (For AC or DC current range only) : Provides DC
voltage output inproportiontotheACorDCcurrentreading.(See
section 3.4, OUTPUT Terminal.) output is connected to a recording
device such as a chart recorder for long hour monitoring. No output is
availableonvoltageandresistanceranges.
(10)Lo Terminal : Accepts the black test lead for voltage or resistance
measurement.
(11)HiTerminal:Acceptstheredtestleadforvoltageorresistancemeas-
urement.

IM CL255 3
(12)SafetyHandStrap:Preventstheinstrumentfromslippingoffthehand
duringuse.
(13)Test Leads (Model 98072) : Connected to Lo and Hi terminals for
voltageorresistancemeasurement.
(14)Barrier：It is a part providing protection against electrical shock and
ensuringtheminimumrequiredairandcreepagedistances.

4 IM CL255
2. Measurement
2.1PreparationforMeasurement
CAUTION
●Thejawsectionisadelicate,precisionsensor.Donotsubjectthejaw
tounreasonablystrongshock,vibration,orforcewhenusingit.
●If dust gets into the tops of the jaws, remove it immediately. Do not
close the jaws when dust is trapped in its joints as the sensor may
break.
●Please check that the Function Selector switch is set to the desired
posi-tionbeforemeasurement.
2.2DCCurrentMeasurement
WARNING
●Do not make measurement on a circuit above 1000VDC. This may
cause shock hazard or damage to the instrument or equipment under
test.
●Donotmakecurrentmeasurementwiththetestleadsconnectedtothe
HiandLoterminals.
●Keepyourfingersandhandsbehindthebarrierduringmeasurement.
(1)SettheFunctionSelectorswitchtothe" A"position."DC"should
beshownontheupperleftcornerofthedisplay.
(2)With the transformer jaws closed and without clamping them onto the
conductor,pressthe buttonforaboutonesecondtozeroadjust
the display. (Zero adjust feature is for 400A range only.) When zero
adjustmentiscompleted," "appearsonthedisplay.
(3)Press the open/close lever to open the transformer jaws and clamp
them onto the conductor under test, then take the reading on the
display. The most accurate reading will be obtained by keeping the
conductoratthecenterofthetransformerjaws.

IM CL255 5
NOTE
●During current measurement, keep the transformer jaws fully closed.
Otherwise,accuratemeasurementcannotbemade.Themaximum
measurableconductorsizeisapprox.55mmindiameter.
●Whenthecurrentflowsfromtheupside(thedisplayside)tothe
underside of the instrument, the polarity of the reading is positive and
viceversa.
●The button may not completely zero adjust the output voltage
from the OUTPUT terminal. In this case, make zero adjustment on the
recordingdevice.
●TuringtheFunctionSelectorswitch toapositionotherthanDCA
cancelsthezeroadjustment.
2.3ACCurrentMeasurement
WARNING
●Neverusetheinstrumentonacircuitabove750VAC.Thismaycause
electrical shock hazard and damage to the instrument or the circuit
undertest.
●Donotmake measurementwiththebatterycompartmentcover
removed.
●Keepyourfingersandhandsbehindthebarrierduringmeasurement.
(1)SettheFunctionSelectorswitchtothe" A"position."AC"shouldbe
shownontheupperleftcornerofthedisplay.
(2)Press the open/close lever to open the transformer jaws and clamp
themontoasingleconductorandtakethereadingonthedisplay.The
mostaccuratereadingwillbeobtainedbykeepingtheconductoratthe
centerofthetransformerjaws.

6 IM CL255
NOTE
●During current measurement, keep the transformer jaws fully closed.
Otherwise, accurate measurements cannot be taken. Maximum conduc-
torsizeis55mmindiameter.
●Zeroadjustment is notnecessaryinAC current measurement.Thereis
nopolarityinthereadingeither.
●Whenthecurrentundertestmeasures3%ofthefullscaleorless,orthe
frequencyofthecurrentislow,"LoHz"isindicatedonthedisplay.
2.4DCVoltageMeasurement
WARNING

Never use the instrument on a circuit above 1000VDC. This may cause
electricalshockhazardanddamagetotheinstrumentorthecircuitundertest.
Keepyourfingersandhandsbehindthebarrierduringmeasurement.
(1)SettheFunctionSelectorswitchtothe" V"position."DC"should
beshownontheupperleftcornerofthedisplay.
(2)SlidetheterminalcovertothelefttodisclosetheHiandLoterminals.
PlugtheredtestleadintotheHiterminalandtheblacktestleadintoLo
terminal.
(3)Connectthetipoftheredandblacktestleadstothepositive(+)and
negative(−)sidesofthecircuitundertestrespectively.Takethereading
onthedisplay.

IM CL255 7
2.5ACVoltageMeasurements
WARNING

Neverusetheinstrumentonacircuitabove750VAC.Thismaycauseelec-
tricalshockhazardanddamagetotheinstrumentorthecircuitundertest.
(1)SettheFunctionSelectorswitchtothe" V"position."AC"shouldbe
shownontheupperleftcornerofthedisplay.
(2)SlidetheterminalcovertothelefttodisclosetheHiandLoterminals.
PlugtheredtestleadintoHiterminalandtheblacktestleadintotheLo
terminal.
(3)Connectthetipoftheredandblacktestleadstothecircuitundertest
andtakethereadingonthedisplay.
NOTE
Whenthe voltageundertestmeasures3% ofthefullscaleor less,orthe
frequencyofthevoltageislow,"LoHz"isindicatedonthedisplay.

8 IM CL255
2.6ResistanceMeasurement
WARNING

Neverusetheinstrumentonanenergizedcircuit.
(1)Set the Function Selector switch to the " " position. The "Ω"
shouldbeshownontheupperrightcornerofthedisplay.
(2)SlidetheterminalcovertothelefttodisclosetheHiandLoterminals.
Plugtheredtest lead intotheHiterminalandtheblacktestleadinto
theLoterminal.
(3)Withthetipofthetestleadsshortedtogether,pressthe button
tooffsettheresistanceofthetestleads.
(4)Connectthetip ofthetestleadstothecircuitundertestandtakethe
readingonthedisplay.
2.7ContinuityCheck(400Ωrangefixed)
Thecontinuitycheckmodeisenabledbypressingthe button
on resistance range. " " and "Ω" is indicated on the display to show
the in-strument in the continuity check mode. The buzzer beeps, if the
resistanceundertestis20Ωorless.
#WARNING

Neverusetheinstrumentonanenergizedcircuit.
(1)SettheFunctionSelectorswitchtothe" "position.
(2)SlidetheterminalcovertothelefttodisclosetheHiandLoterminals.
Plugtheredtest lead intotheHiterminalandtheblacktestleadinto
theLoterminal.
(3)Withthetipofthetestleadsshortedtogether,pressthe button
tooffsettheresistanceofthetestleads.

IM CL255 9
(4)Press the  button once to enter from the normal mode to the
continuitycheckmode." "shouldbeindicatedonthedisplay.
(5)Connect the tip of the test leads to the circuit under test. If the
re-sistanceis20Ωorless,thebuzzerbeeps.
2.8FrequencyMeasurement
●OnACAorACVrange,thefrequencyofthecurrentorvoltageundertest
canbecountedandshownonthedisplay.
●Inthefrequencymeasurementmode," "isindicatedonthedisplay.
●Triggerthresholdisapprox.10VforACvoltageandapprox.10AforAC
current.At frequencymeasurement,incaseof lowinputsignal,itoften
happensthat measurement cannotbemade. Because rangeis fixed at
400VforACvoltageandat400AforACcurrent.

WARNING
●Neverusetheinstrumentonahighvoltagecircuitabove750VAC.This
maycauseelectricalshockhazardanddamagetotheinstrumentorthe
circuitundertest.
●Donotmakecurrentmeasurementwiththetestleadspluggedintothe
instrument.
(1)SettheFunctionSelectorswitchtothe" A"or" V"position.
(2)Press the  buttonthree timesto enter fromthe normalmode to
the frequency measurement mode. " " should be indicated on the
display.
(3)FollowinstructionsforACAorACVmeasurementandtakethefrequen-
cyreading.
NOTE
Whenthe voltageundertestmeasures3% ofthefullscaleor less,orthe
frequencyofthecurrentorvoltageis40Hzorless,"LoHz"isindicatedon
thedisplay.

10 IM CL255
2.9PeakMeasurement
●Inthismode," "isindicatedonthedisplay.
●In the PEAK mode, the display shows current or voltage's crest in
effectivevalue.(Forexample,whenthecurrentorvoltageissi-nusoidal,
the reading equals the crest value divided by the square root of two.)
Thedisplayreadingisconstantlyupdatedwithamaximumcrest.
●Response time is 300ms in DC measurement and 10ms in AC
measurement.

WARNING
●Never use the instrument on a circuit above 750VAC or 1000VDC.
Thismaycause electricalshockhazardanddamagetothe instrument
orthecircuitundertest.
●Donotmakemeasurementwiththetestleadspluggedintothe instru-
ment.
(1)ThePEAKmodeisavailableonDCA,ACA,DCVandDCAranges.
Set the Function Selector switch to the " A ", " A ", " V " or
" V"position.
Note:OnlyonDCArange,pressthe buttonforaboutonesecond
tozeroadjustthereadingwiththetransformerjawsclosed.
(2)Press the  button twice to enter from the normal mode to
thePEAKmode." "shouldbeshownonthedisplay.
(3)FollowinstructionsforDCA,ACA,DCVorACVmeasurement.
(4)Foraccuratereading,pressthe buttontoresetthereadingafter
clampingontotheconductorormakingtestleadconnectionstothecir-
cuitundertest.Thenproceedtomeasurement.
NOTE
●In the PEAK mode, theauto-ranging featureis disabledand measuring
rangesarefixedasfollows.
 DCAandACA:0to400.0A
 DCAandACV:0to400.0V
●TheSleepfunctionisdisabledinthePEAKmodeaswell.

IM CL255 11
2.10AverageMeasurement
ThismodeisavailableonACV,DCV,ACAandDCAranges.
(1)Set the Function Selector switch to the " A ", " A ", " V " or
" V"position.
(2)Press the  button once to enter from the normal mode to the
Averagemode." "shouldbeindicatedonthedisplay.
(3)FollowinstructionsforACV,DCV,ACAorDCAmeasurement.
(4)Thedisplayshowsarunningaverageofsixreadingsoveranintervalof
about2seconds.

12 IM CL255
3. OtherFunctions
3.1SleepFunction
Thisisafunctiontoprevent the instrument from beingleftpoweredonin
ordertoconservebatterylife.Thisfunctioncausestheinstrumenttoenter
theSleep(powered-down) modeabout30minutesafterthelastswitch or
buttonoperation.
Toexitthe Sleep mode,turntheFunctionSelectorswitchbackto "OFF",
thentoanyotherposition,orpressanybutton.
ThecurrentisconsumedalittleintheSleepmode.
NOTE
●Connectingtheplugto theOUTPUTterminaldisablestheSleep
function.Thefunctionisenabledonremovingtheplugfromtheterminal.
●TheSleepfunctionisdisabledinthePEAKmeasurementmode.
3.2DataHoldFunction
Thisisafunctionusedtofreezethemeasuredvalueonthedisplay.Press
theDataHoldbuttontofreezethereading.Thereadingwillbeheldregard-
lessofsubsequentvariationininput." "isshownontheupperrightcor-
nerofthedisplaywhiletheinstrumentisintheDataHoldmode.
ToexittheDataHoldmode,presstheDataHoldbuttonagain.
NOTE
Iftheinstrumentin the Data Holdmodegoesinto"sleep",itwillreturnto
thenormalmode.
3.3LoHzFunction
InACVorACArange,iffrequencyofthevoltageorcurrentunder
test is 40Hz or lower, the display indicates "LoHz" and sample rate is
automatically switched from the normal 3 times/sec to 2 times/sec to
reduce fluctuation of the reading. "LoHz" is also indicated where input is
3%offullscaleorless.

IM CL255 13
3.4OUTPUTTerminal(Forcurrentrangesonly)
WARNING
●Never use the instrument on a circuit above 750VAC or 1000VDC.
Thismaycauseelectricalshockhazardanddamagetotheinstrumentor
thecircuitundertest.
●NeverapplyvoltagetotheOUTPUTterminal.
When the plug is inserted into the output terminal, auto-range function is
cleared.
SettherangedependingonthestateofDataHoldSwitch.
 DataHoldSwitchOFF 400Arange
 DataHoldSwitchON 2000Arange
NOTE
Aftermeasurement,besuretoreturnDataHoldswitchto"OFF"position.
(1)Attach the outputplug cable(sold separately : 98076 or98077) to a
connection lead so that the output voltage can be connected to a
recordingdevicesuchasachartrecorder.
(2)Slide the terminal cover to the right to disclose the OUTPUT terminal
and insert the output plug into the terminal. Make connection to the
recordingdevice.
(3)SettheFunctionSelectorswitchtothedesiredposition(ACAorDCA)
andfollowappropriatemeasurementinstructions.

14 IM CL255
NOTE
●Consulttheoutputvoltagespecificationsshowninchapter5andadjust
thesensitivityoftherecordingdevice.
●OnDCcurrentrange,the buttonmaynotcompletelyzeroadjust
the output voltage from the OUTPUT terminal. In this case, make zero
adjustmentontherecordingdevice.
●Connecting the plug to the OUTPUT terminal disables the Sleep
function.Thefunctionisenabledonremovingtheplugfromtheterminal.
Thein-strumententersSleepmode30minutesaftertheplugisremoved.
●ForlonghoursofuseoftheOUTPUTterminal,useanAlkalinebattery,
whichwillextendcontinuousrecordingtimeuptoabout24hours.
3.5OptionalAccessories
ClampAdapterModel99025(ForACcurrentmeasurementonly)
Theclampadapter(99025)hasbeendiscontinued.
The clamp adapter (99025) is designed to increase the measuring
capability of a clamp meter. With the use of the Clamp Adapter, you can
notonlyextendcurrentrangeover3000A,butalsoclamponalargebus-
barorcon-ductor.
(1)SettheFunctionSelectorswitchtothe" A"position.
(2)Asshowninthefigurebelow,clampModelCL255ontothepickupcoil
ofModel99025.
(3)ClampModel99025ontothebus-barorconductorundertest.
(4)TakethereadingonModelCL255andmultiplyitby10.

IM CL255 15
4. BatteryReplacement
WARNING
To avoid electric shock hazard, make sure to set the Function Selector
switch to "OFF" and remove the test leads from the instrument before
tryingtoreplacebattery.

CAUTION
Makesuretoinstallbatteryincorrectpolarityasindicatedinbatterycom-
partment.
If the battery voltage becomes too low for the instrument to operate
normally," "isshownonthedisplay.Then,replacethebattery.Note
that when the battery is completely exhausted, the display blanks without
""shown.
(1)SettheFunctionSelectorswitchtothe"OFF"position.
(2)Unscrew and remove the battery compartment on the bottom of the
instrument.
(3)Replacethebatteryobservingcorrectpolarity.Useanew6LR61(Alka-
line)or6F22(Manganese)9Vbattery.
(4)Re-placeandscrewthebatterycompartmentcover.