YOKOGAWA WT310E User manual

IM WT310E-01EN
2nd Edition
User’s Manual
WT310E/WT310EH/WT332E/WT333E
Digital Power Meter

i
IM WT310E-01EN
Thank you for purchasing the WT310E, WT310EH, WT332E, or WT333E Digital Power Meter. This instrument
is a power measurement instrument that can measure parameters such as voltage, current, and power.
This User’s Manual explains the features of this instrument and how to use them. To ensure correct
use, please read this manual thoroughly before beginning operation.
Keep this manual in a safe place for quick reference in the event that a question arises.
List of Manuals
The following manuals, including this one, are provided as manuals for this instrument. Please read all manuals.
Manual Title Manual No. Description
WT310E/WT310EH/WT332E/WT333E
Digital Power Meter User’s Manual IM WT310E-01EN This manual. The manual explains all features of this instrument, except for the communication interface
features, and how to use them.
WT310E/WT310EH/WT332E/WT333E
Digital Power Meter Getting Started
Guide
IM WT310E-02EN Provided as a printed manual. This manual explains
the handling precautions and basic operations of this
instrument and provides an overview of its features.
WT310E/WT310EH/WT332E/WT333E
Digital Power Meter Communication
Interface User’s Manual
IM WT310E-17EN This manual explains the communication interface
features of this instrument and how to use them.
WT310E/WT310EH/WT332E/WT333E
Digital Power Meter IM WT310E-92Z1 Document for China
PDF files of all the manuals above are included in the accompanying CD.
The “EN” and “Z1” in the manual numbers are the language codes.
Contact information of Yokogawa offices worldwide is provided on the following sheet.
Document No. Description
PIM 113-01Z2 List of worldwide contacts
Notes
• Thecontentsofthismanualaresubjecttochangewithoutpriornoticeasaresultofcontinuing
improvements to the instrument’s performance and functionality. The figures given in this manual
may differ from those that actually appear on your screen.
• Everyefforthasbeenmadeinthepreparationofthismanualtoensuretheaccuracyofitscontents.However,
should you have any questions or find any errors, please contact your nearest YOKOGAWA dealer.
• Copyingorreproducingalloranypartofthecontentsofthismanualwithoutthepermissionof
YOKOGAWAis strictly prohibited.
• SafetyprecautionsareprovidedintheGettingStartedGuide,IMWT310E-02EN.Besureto
observe the safety precautions.
• TheTCP/IPsoftwareofthisproductandthedocumentsconcerningithavebeendeveloped/created
byYOKOGAWAbasedontheBSDNetworkingSoftware,Release1thathasbeenlicensedfrom
theRegentsoftheUniversityofCalifornia.
Trademarks
• Microsoft,InternetExplorer,MS-DOS,Windows,WindowsVista,Windows7,Windows8,and
Windows8.1areeitherregisteredtrademarksortrademarksofMicrosoftCorporationintheUnited
States and/or other countries.
• AdobeandAcrobatareeitherregisteredtrademarksortrademarksofAdobeSystemsIncorporated.
• ModbusisaregisteredtrademarkofAEGSchneider.
• Inthismanual,the® and TM symbols do not accompany their respective registered trademark or
trademark names.
• Othercompanyandproductnamesareregisteredtrademarksortrademarksoftheirrespectiveholders.
Revisions
• September2015 1stEdition
• October2017 2ndEdition
2nd Edition: October 2017 (YMI)
AllRightsReserved,Copyright©2015YokogawaTest&MeasurementCorporation

ii IM WT310E-01EN
Symbols and Notation Used in This Manual
Units
k: Denotes 1000. Example: 100 kHz (frequency)
K:Denotes1024. Example:720KB(filesize)
Notes
The notes and cautions in this manual are categorized using the following symbols.
Improper handling or use can lead to injury to the user or damage to the
instrument. This symbol appears on the instrument to indicate that the user must
refer to the user’s manual for special instructions. The same symbol appears in
the corresponding place in the user’s manual to identify those instructions. In the
user’smanual,thesymbolisusedinconjunctionwiththeword“WARNING”or
“CAUTION.”
WARNING Callsattentiontoactionsorconditionsthatcouldcauseseriousorfatalinjuryto
the user, and precautions that can be taken to prevent such occurrences.
CAUTION Callsattentiontoactionsorconditionsthatcouldcauselightinjurytotheuser
or cause damage to the instrument or user’s data, and precautions that can be
taken to prevent such occurrences.
French
AVERTISSEMENT Attire l’attention sur des gestes ou des conditions susceptibles
de provoquer des blessures graves (voire mortelles), et sur les
précautions de sécurité pouvant prévenir de tels accidents.
ATTENTION Attire l’attention sur des gestes ou des conditions susceptibles de
provoquer des blessures légères ou d’endommager l’instrument ou les
données de l’utilisateur, et sur les précautions de sécurité susceptibles
de prévenir de tels accidents.
Note Calls attention to information that is important for the proper operation of the
software.
Characters That Appear on the 7-Segment LED
Becausethisinstrumentusesa7-segmentLEDdisplay,numbers,letters,andmathematicalsymbols
are displayed using special characters in the manner shown below. Some of the characters shown
below are not used by this instrument.
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
Lowercase c
Lowercase h
U
V
W
X
Y
Z
+
-
×
÷
^ (exponentiation)

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IM WT310E-01EN
Symbols and Conventions Used in Procedural Explanations
The contents of the procedural explanations are indicated using the following symbols.
This mark appears on the right side of the page to indicate features and settings that can be
operatedandconfiguredusingtheWTViewerFreePlusapplicationsoftware,whichcomeswiththe
instrument.
Procedure Operations are explained using flowcharts. See the example below for an
explanation of how various operations are indicated. All procedures are written
under the assumption that you are starting operation at the beginning of the
procedure, so you may not need to carry out all the steps in a procedure when
you are changing the settings.
Example: Operations for turning the storage feature on and off
4.
2.
(Display C)
Configure the storage feature.
(Display B)
1.
3. 5.
Confirm the
setting. Close menu.
6.
The above flow chart indicates the following operations.
You can configure items that are blinking.
1. Press the SHIFT key so that it illuminates, and then press SETUP (UTILITY).
AmenuappearsindisplayB.
2. Use ▲or ▼to select StorE.
Pressing either key cycles through 9 menu items.
3. Press SET to confirm the selection of StorE.
The StorE function menu that you selected in step 2 appears in display C.
4. Use ▲or ▼to select oFF or on.
Pressing either key cycles through 3 menu items.
5. Press SET to confirm the selection of oFF.
The selected or set item is confirmed when you press SET.
AmenuappearsindisplayB.
6. Press HOLD (ESC) to return the menu display to the measured data display.
• Whenyouaremakinganumberpositive(nosign)ornegative(–)orsettinganumber,whenthe
digit in the display that the input will be added to is blank, an underscore flashes at the position of
the digit.
• Whileyouareperformingmenuoperations,toleavethemenudisplay,pressHOLD(ESC).All
setting changes that you have confirmed by pressing the SET key will be reflected in the settings.
Explanation This section describes the setup items and the limitations regarding the
procedures. It may not give a detailed explanation of the feature. For a detailed
explanation of the feature, see chapter 1.
Conventions Used in This Manual

iv IM WT310E-01EN
Entering Values
Selecting a Value
The digit that is blinking is the one that is currently being set.
Use▲or▼toselectanumber.
Moving the Digit That Is Being Set
Press SHIFT+▼(►) to move the digit that is being set to the right.
If you press SHIFT+▼(►) when the digit that is being set is the digit that is furthest to the right, the
digit that is being set will switch to the leftmost digit that can be set.
Moving the Decimal Point
Press SHIFT+▲(.)tomovethedecimalpointtotheright.
IfyoupressSHIFT+▲(.)whenthedecimalpointisasfartotherightasitcanbe,thedecimalpoint
will move to the leftmost possible position.
+
+Moves the digit that is being set to the right
Moves the decimal point to the right
Increases
the number
Reduces
the number

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IM WT310E-01EN
There is no paragraph to attach .
1
2
3
4
5
6
7
8
App
Index
Contents
Symbols and Notation Used in This Manual.....................................................................................ii
EnteringValues................................................................................................................................iv
Chapter 1 Features
1.1 Items That This Instrument Can Measure (Measurement functions) ............................... 1-1
1.2 Measurement Conditions ................................................................................................. 1-5
1.3 HoldingMeasuredValuesandPerformingSingleMeasurements ................................. 1-13
1.4 Measuring Power ........................................................................................................... 1-14
1.5 IntegratedPower(Watthour) ......................................................................................... 1-15
1.6 Harmonic Measurement (Option)................................................................................... 1-17
1.7 Storing Measured Data and Saving and Loading Setup Parameters............................. 1-18
1.8 CommunicationFunctions.............................................................................................. 1-19
1.9 Other Features............................................................................................................... 1-20
Chapter 2 Measurement Conditions
2.1 Setting the Measurement Mode....................................................................................... 2-1
2.2 Configuring the Wiring System Settings (WT332E/WT333E only)................................... 2-3
2.3 SettingtheMeasurementRangeWhenUsingDirectInput.............................................. 2-4
2.4 SettingtheMeasurementRangesWhenUsinganExternalCurrentSensor(Option)..... 2-9
2.5 SettingtheScalingFeatureWhenUsingaVTorCT..................................................... 2-13
2.6 ConfiguringMeasurementRangeSkipping.................................................................... 2-16
2.7 Setting the Crest Factor ................................................................................................. 2-17
2.8 SettingtheMeasurementPeriod.................................................................................... 2-18
2.9 Configuring the Input Filters........................................................................................... 2-19
2.10 Setting the Data Update Interval.................................................................................... 2-21
2.11 Setting Averaging ........................................................................................................... 2-23
Chapter 3 Holding Measured Values and Performing Single Measurements
3.1 HoldingMeasuredValues................................................................................................. 3-1
3.2 Performing Single Measurements.................................................................................... 3-2
Chapter 4 Measuring Power
4.1 DisplayingVoltages,Currents,andActivePowers........................................................... 4-1
4.2 DisplayingApparentPowers,ReactivePowers,andPowerFactors ............................... 4-3
4.3 Displaying Phase Angles and Frequencies...................................................................... 4-5
4.4 DisplayingPeakValues.................................................................................................... 4-7
4.5
DisplayingtheEfficiency(WT332E/WT333Eonly),CrestFactors,theResultsofComputations
UsingBasicArithmetic,andAverageActivePowers .................................................................4-8
4.6 Setting the MAX Hold Feature........................................................................................ 4-15
4.7 Setting the Number of Displayed Digits.......................................................................... 4-16
Chapter 5 Integration
5.1 IntegrationFeature ........................................................................................................... 5-1
5.2 SettingtheIntegrationModeandTimer ........................................................................... 5-5
5.3 DisplayingIntegratedValues............................................................................................ 5-6
5.4 NotesaboutUsingIntegration.......................................................................................... 5-9

vi IM WT310E-01EN
Chapter 6 Harmonic Measurement (Option)
6.1 Harmonic Measurement Feature...................................................................................... 6-1
6.2 Displaying Harmonic Measurement Data......................................................................... 6-3
6.3 Setting the PLL Source, Measured Harmonic Order, and THD Equation......................... 6-6
Chapter 7 Storing Measured Data and Saving and Loading Setup Parameters
7.1 Storing Measured Data .................................................................................................... 7-1
7.2 Saving and Loading Setup Parameters............................................................................ 7-3
Chapter 8 Other Features
8.1 ViewingSystemInformation............................................................................................. 8-1
8.2 InitializingtheSettings...................................................................................................... 8-2
8.3 PerformingZero-LevelCompensation ............................................................................. 8-4
8.4 ConfiguringD/AOutputItems(Option)............................................................................. 8-5
8.5 EnablingKeyProtection ..................................................................................................8-11
8.6 CarryingOutSelf-Tests(Selftest)................................................................................... 8-12
Appendix Appendix 1 Symbols and Determination of Measurement Functions ...................................App-1
Appendix2 PowerBasics(Power,harmonics,andACRLCcircuits) ...................................App-6
Appendix3 PowerRange ...................................................................................................App-14
Appendix 4 Setting the Measurement Period......................................................................App-17
Appendix5 MeasurementAccuracyandMeasurementError.............................................App-21
Appendix 6 Menu Transition Diagram.................................................................................App-26
Appendix7 BlockDiagram..................................................................................................App-34
Index
Contents

1-1
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
1.1 Items That This Instrument Can Measure
(Measurement functions)
The items that you can measure with this instrument are listed below. For details about how the
values of measurement functions are determined, see appendix 1. For explanations of the terms
measurementfunction,inputelement,wiringunit,andΣfunction,see“WhatIsaMeasurement
Function?” (page 1-4).
WT310E and WT310EH
 TheWT310EandWT310EHareonlyequippedwithoneinputelement.Becauseofthis,they
can only measure single-phase measurement functions. They cannot measure comprehensive
measurementfunctionsthattreatmultipleinputelementsasasinglewiringunit(Σfunctions).
WT332E/WT333E
 TheWT332E/WT333Eisequippedwithtwoorthreeinputelements.Becauseofthis,theWT332E/
WT333E can measure not only single-phase measurement functions for each input element but
alsomeasuremeasurementfunctionsthattreatmultiplephasesasasinglewiringunit(Σfunctions).
The measurement functions that you can measure using this instrument are divided into normal
measurement and harmonic measurement and listed in the following table.
Measurement Functions Used in Normal Measurement
Voltage
Measurement
Function
(Symbol)
Panel Indicator
Light1Description Measured for Each Input
Element
Measured for
Wiring Units
(WT332E/
WT333E only)
U(RMS) V True rms voltage Yes Yes
U(VOLTAGEMEAN) V Rectifiedmeanvoltagecalibrated
to the rms value Yes Yes
U (DC) VLinear voltage average Yes Yes
U+pk Vpk Maximum voltage Yes No
U-pk Vpk Minimum voltage Yes No
Cf U2MATH Voltagecrestfactor Yes No
Yes: Measured. No: Not measured.
1 Panel indicators indicate the unit of the measured value and the item that is being measured.
They appear on the right or left side of the 7-segment LED display that shows the measured data.
2 This measurement function is set using the MATH feature of this instrument.
Current
Measurement
Function
(Symbol)
Panel Indicator
Light Description Measured for Each Input
Element
Measured for
Wiring Units
(WT332E/
WT333E only)
I(RMS) A True rms current Yes Yes
I (DC) A Linear current average Yes Yes
I+pk Apk Maximum current Yes No
I-pk Apk Minimum current Yes No
Cf I*MATH Current crest factor Yes No
* This measurement function is set using the MATH feature of this instrument.
Chapter 1 Features

1-2 IM WT310E-01EN
Power
Measurement
Function
(Symbol)
Panel Indicator
Light Description Measured for Each Input
Element
Measured for
Wiring Units
(WT332E/
WT333E only)
P W Active power Yes Yes
SVA Apparent power Yes Yes
Q var Reactivepower Yes Yes
λPF Power factor Yes Yes
Φ° Phase difference Yes Yes
P+pk Wpk Maximum power Yes No
P-pk Wpk Minimum power Yes No
Frequency
Measurement
Function
(Symbol)
Panel Indicator
Light Description Measured for Each Input
Element
Measured for
Wiring Units
(WT332E/
WT333E only)
fU VHz Voltagefrequency Yes No
fI AHz Current frequency Yes No
fPLL (PLL U) VHz Frequency of PLL voltage*Yes No
fPLL (PLL I) AHz Frequency of PLL current*Yes No
* Only on models with the harmonic measurement option
Integrated Power (Watt hour)
Measurement
Function
(Symbol)
Panel Indicator
Light Description Measured for Each Input
Element
Measured for
Wiring Units
(WT332E/
WT333E only)
Time Time Integration time Yes No
WP Wh Sum of positive and negative watt
hours Yes Yes
WP± Wh± Positive or negative watt hours Yes Yes
q Ah Sum of positive and negative
ampere hours Yes Yes
q± Ah± Positive or negative ampere hour Yes Yes
AVP*MATH Average active power during
integration Yes Yes
* This measurement function is set using the MATH feature of this instrument.
Efficiency (WT332E/WT333E only)*
Measurement
Function
(Symbol)
Panel Indicator
Light Description
EFFi MATH Efficiency
* This measurement function is set using the MATH feature of the WT332E/WT333E.
Basic Arithmetic*
Measurement
Function
(Symbol)
Panel Indicator
Light Description
A+B MATH A+B
A-B MATH A-B
A×B MATH A×B
A÷B MATH A÷B
A÷B^2 MATH A÷B2
A^2÷B MATH A2÷B
* This measurement function is set using the MATH feature of this instrument.
1.1 Items That This Instrument Can Measure

1-3
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
Measurement Functions Used in Harmonic Measurement (Option)
Harmonic measurement functions are measured for each input element and only work with single-
phase measurement. They cannot measure comprehensive measurement functions that treat multiple
phasesasasinglewiringunit(Σfunctions).
Measurement
Function
(Symbol)
Panel Indicator
Light Description
U(k) V Rmsvoltagevalueofharmonicorderk
I(k) A Rmscurrentvalueofharmonicorderk
P(k) W Active power of harmonic order k
λ(k) PF Power factor of the fundamental wave (1st harmonic)
Φ(k) V°or
A° Phase difference between the fundamental voltage and fundamental current when the harmonic order k is the 1st harmonic (fundamental
wave)
Uthd THDV% Total harmonic voltage distortion
Ithd THDA% Total harmonic current distortion
Uhdf(k) V% Harmonic distortion factor of voltage for harmonic order k
Ihdf(k) A% Harmonic distortion factor of current for harmonic order k
Phdf(k) W% Harmonic distortion factor of power for harmonic order k
ΦU(k) V° Phase difference between the voltage of harmonic order k and and the
fundamental voltage
ΦI(k) A° Phase difference between the current of harmonic order k and the
fundamental current
k: The harmonic order, which is indicated in displayA.
Harmonic Measurement Function Orders
The harmonic orders that you can specify are indicated below.
Measurement
Function
(Symbol)
Panel Indicator
Light Total Value (Total rms value) 1 (fundamental wave) Harmonics
U(k) VYes Yes 2to50*
I(k) A Yes Yes 2to50*
P(k) W Yes Yes 2to50*
λ(k) PF No Yes No
Φ(k) V°or
A° No Yes No
Uthd THDV% Yes No No
Ithd THDA% Yes No No
Uhdf(k) V% No Yes 2to50*
Ihdf(k) A% No Yes 2to50*
Phdf(k) W% No Yes 2to50*
ΦU(k) V° No No 2to50*
ΦI(k) A° No No 2to50*
k: The harmonic order
* The maximum measured harmonic order varies depending on the frequency of the fundamental
wave. (See section 7.4, “Harmonic Measurement,” in the Getting Started Guide, IM WT310E-
02EN.)
1.1 Items That This Instrument Can Measure

1-4 IM WT310E-01EN
What Is a Measurement Function?
Measurement Function
The physical values—such as rms voltage, average current, power, and phase difference—that this
instrument measures and displays are called measurement functions. Each measurement function
is displayed using a symbol that corresponds to its physical value. For example, “U” corresponds to
thevoltage.Theunitis“V.”WhenthemeasurementmodeisRMS(seesection1.2,“Measurement
Conditions”), the true rms voltage is displayed.
WT310E and WT310EH
Input Element
An input element is a set of input terminals that a single phase of voltage and current that you want
to measure can be applied to. The WT310E/WT310EH has one input element.
Input element
Voltage inputCurrent input
Wiring System
The WT310E/WT310EH uses a single-phase, two-wire system.
Wiring Units and Σ Functions
The WT310E/WT310EH does not have multiple input elements that can be combined into wiring
unitsandΣfunctions.
WT332E/WT333E
Input Elements
An input element is a set of input terminals that a single phase of voltage and current that you
want to measure can be applied to. The WT333E can be equipped with three input elements. The
element numbers range from 1 to 3.
Wiring Systems
To measure the power of various single-phase and three phase power transmission systems using
the WT332E/WT333E, not only can you specify a single-phase, two-wire system, you can also
specify a single-phase, three-wire system; a three-phase, three-wire system; a three-phase, four-
wire system; or a three-phase, three-wire system that uses the three-voltage, three-current method.
Wiring Unit
A wiring unit is a set of two or three input elements that are grouped to measure three-phase power.
WiringunitsarerepresentedbytheΣsymbol.
Σ Functions
AmeasurementfunctionofawiringunitiscalledaΣfunction.Forexample,“UΣ”corresponds
totheaverageofthevoltagesoftheinputelementsthatareassignedtowiringunitΣ.Whenthe
measurementmodeisRMS,thetruermsvoltageisdisplayed.
Three-phase, four-wire
Σ
Input elements
Wiring system
Symbol indicating the wiring unit.
Voltage input
Current input
12 3
1.1 Items That This Instrument Can Measure

1-5
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
1.2 Measurement Conditions
Voltage and Current Measurement Modes (For procedures, see
section 2.1)
Youcanselectoneofthefollowingthreevoltagemeasurementmodes:RMS,MEAN(VOLTAGE
MEAN), and DC.
Youcanselectoneofthefollowingtwocurrentmeasurementmodes:RMSandDC.
RMS (True RMS)
The true voltage or current rms value.
T
1T
0
(t)2dt f(t) : Input signal
T : One period of the input signal
MEAN (VOLTAGE MEAN, rectified mean value calibrated to the
rms value)
One period of the voltage is rectified and the resulting average is multiplied by the factor that would
yield the true rms value if the applied signal were a sine wave. When sine waves are measured, the
valuesobtainedinthismodearethesameasthoseobtainedinRMSmode.Thevaluesdifferfrom
thoseobtainedinRMSmodewhendistortedwavesorDCwavesaremeasured.
T
1(t) dt f(t) : Input signal
T : One period of the input signal
2 2 ·
T
0
π
DC (Linear average)
The average of one period of the voltage or current. This mode is useful for determining the average
value of a DC input signal or the value of a DC signal that is superimposed on an AC signal.
T
1
T
0
(t) dt f(t) : Input signal
T : One period of the input signal

1-6 IM WT310E-01EN
Wiring Systems (For procedures, see section 2.1)
The wiring systems that you can select vary depending on the model.
WT310E and WT310EH
The WT310E and WT310EH are only equipped with one input element. You can measure single-
phase,two-wiresystems.Becausethereisonlyoneinputelement,youcannotselectdifferentwiring
systems.
WT332E (Two Input Element Model)
The WT332E is equipped with two input elements (element 1 and element 3). On the WT332E, you
can select the following wiring systems.
Wiring System Description Elements
1P3W Single-phase, three-wire Element 1 and element 3
3P3W Three-phase, three-wire Element 1 and element 3
The measured data when a single-phase, two-wire system (1P2W) has been specified is the measured
data for elements 1 and 3.
The measured data for a single-phase, two-wire system will be measured correctly regardless of which
of the above wiring systems you select.
WT333E (Three Input Element Model)
The WT333E is equipped with three input elements (element 1, element 2, and element 3). On the
WT333E, you can select the following wiring systems.
Wiring System Description Elements
1P3W Single-phase, three-wire Element 1 and element 3. Element 2 is 1P2W.
3P3W Three-phase, three-wire Element 1 and element 3. Element 2 is 1P2W.
3P4W Three-phase, four-wire Elements 1, 2, and 3
3V3A Three-voltage, three-
current method Elements 1, 2, and 3
The measured data when a single-phase, two-wire system (1P2W) has been specified is the
measured data for elements 1, 2, and 3. The measured data for a single-phase, two-wire system will
be measured correctly regardless of which of the above wiring systems you select.
1.2 Measurement Conditions

1-7
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
Measurement Ranges (For procedures, see section 2.3)
Specify the measurement ranges in accordance with the rms values of the voltage and current that you
want to measure. You can specify fixed measurement ranges or have the ranges set automatically.
Fixed Ranges
You can select a range from various options. Even if the size of the input signal changes, the selected
range will not change. For voltage, when the crest factor is set to 3, the maximum range that you can
selectis600V,andtheminimumrangethatyoucanselectis15V.
Whenthecrestfactorissetto6or6a,themaximumrangethatyoucanselectis300V,andthe
minimumrangethatyoucanselectis7.5V.
Auto Range
This instrument automatically switches the range according to the size of the input signal. The ranges
that this instrument switches between are the same ranges that you can select as fixed ranges.
Range Increase
The range is increased when any of the following conditions is met.
• Crestfactor3
UrmsorIrmsexceeds130%ofthemeasurementrange.
UpkorIpkexceedsapproximately300%ofthecurrentlysetmeasurementrange.
• Crestfactor6
UrmsorIrmsexceeds130%ofthemeasurementrange.
UpkorIpkexceedsapproximately600%ofthecurrentlysetmeasurementrange.
• Crestfactor6A
UrmsorIrmsexceeds260%ofthemeasurementrange.
UpkorIpkexceedsapproximately600%ofthecurrentlysetmeasurementrange.
On the WT332E/WT333E, when any of the equipped input elements meets any of the above
conditions, the measurement range is increased.
Range Decrease
The range is decreased when all of the following conditions are met.
• Crestfactor3
• UrmsorIrmsislessthanorequalto30%ofthemeasurementrange.
• UrmsorIrmsislessthanorequalto125%ofthenextlowermeasurementrange.
• UpkorIpkislessthanorequalto300%ofthenextlowermeasurementrange.
• Crestfactor6,6A
• UrmsorIrmsislessthanorequalto30%ofthemeasurementrange.
• UrmsorIrmsislessthanorequalto125%ofthenextlowermeasurementrange.
• UpkorIpkislessthanorequalto600%ofthenextlowermeasurementrange.
On the WT332E/WT333E, when all the input elements meet all the above conditions, the
measurement range is decreased.
Range Skipping (For procedures, see section 2.6)
You can select which measurement ranges to skip (range configuration). Measurement ranges that are
not used are skipped, and this instrument switches between the measurement ranges that you have
chosen to enable. For example, when using the auto range feature to measure the current of a device
thatproduces5Ainoperationmodeand500mAinstandbymode,youcanconfigurerangeskipping
so that the 1 A and 2 A ranges are disabled. When you are measuring the current of the device in
standbymodeinthe500mArangeandthedeviceswitchestooperationmode,theintermediate1A
and2Arangesareskipped,andthedeviceswitchestothe5Arange.Rangeskippingcanreducethe
loss of measured data that can occur when ranges are switched one by one.
You can turn range skipping on and off from the display menu of this instrument. You can specify
which measurement ranges to skip by sending communication commands through the communication
interfaceorbyusingWTViewerFreePlus.
1.2 Measurement Conditions

1-8 IM WT310E-01EN
Measurement range
5A
2A
1A
0.5A
When range skipping is off When range skipping is on
Range skip check box
Peak Over Jump
You can set the measurement range to switch to when a peak over-range occurs and the auto range feature
is enabled. You can set this feature by sending communication commands through the communication
interfaceorbyusingWTViewerFreePlus.Whenthisfeatureisdisabledandapeakover-rangeoccurs,this
instrument raises the measurement range to the next range that has not been set to be skipped.
Setting Measurement Ranges (For procedures, see section 2.3)
There are two ways to set measurement ranges.
Setting Measurement Ranges Using the Measurement Range Menu
 ThemeasurementrangemenuappearswhenyoupressVOLTAGEorCURRENT.Setthe
measurementrangeusingthe▼and▲keys,andthenpressSET.Themeasurementrangewill
change, and the measured data display will reappear.
Setting Measurement Ranges without Displaying the Measurement Range Menu
 ThemeasurementrangemenudoesnotappearwhenyoupressVOLTAGEorCURRENT.Youcan
setthemeasurementrangeusingthe▼and▲keys.
 Press▼or▲toswitchthemeasurementrange.Forafixedperiodoftime,afterthecurrentrange
is displayed, the measured data display will reappear.
There is no need to press SET, so this way of setting the measurement range is convenient in the
following situations.
• Whenyouswitchthemeasurementrangefrequently
• Whenyouwanttoswitchbetweenmeasurementrangesonebyoneandcheckthemeasured
data each time
Example: When you are searching for a measurement range within which over ranges and peak
over-ranges do not occur.
Power Range
The measurement range (power range) for measuring active power, apparent power, and reactive
power is determined as indicated below in accordance with the wiring system, voltage range, and
current range. See appendix 3 for specific power range values.
Wiring System Power Range
1P2W (single-phase, two-wire) Voltagerange×currentrange
1P3W (single-phase, three-wire)
3P3W (three-phase, three-wire)
3V3A(three-voltage,three-currentmethod)
Voltagerange×currentrange×2
3P4W (three-phase, four-wire) Voltagerange×currentrange×3
External Current Sensor Range (Option; for procedures, see
section 2.4)
The output of current sensors that produce voltage, such as shunts and clamps, can be applied to an
element’s external current sensor input terminal (EXT) and measured.
The auto range feature can be used for this applied voltage as well.
External Current Sensor Conversion Ratio (Option; for
procedures, see section 2.4)
Set the conversion ratio used to measure the signal received by the external current sensor input
terminal (EXT) from a current sensor that produces voltage. Set how many millivolts the current sensor
transmits when 1 A of current is applied (conversion ratio).
When using a current sensor that produces current, set the conversion ratio as the CT ratio.
1.2 Measurement Conditions

1-9
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
Scaling (For procedures, see section 2.5)
You can set coefficients for when you apply a voltage or current signal from an external voltage
transformer1or current transformer.2
1 VT(voltagetransformer)
2 CT (current transformer)
VT Ratio and CT Ratio
YoucansettheVTorCTratiotoconvertthevaluesintheappliedsignalanddisplaythevoltageor
current values or waveform from before the voltage or current transformation.
Power Coefficient
Bysettingthepowercoefficient(F),youcandisplaythemeasuredactivepower,apparentpower,and
reactive power after they have been multiplied by a coefficient.
Measurement Function Data before Transformation Transformation Result
VoltageU U2(secondaryoutputoftheVT) U2×V V:VTratio
Current I I2(secondary output of the CT) I2×C C: CT ratio
Active power P P2P2×V×C×F F: Power coefficient
Apparent power S S2S2×V×C×F
ReactivepowerQ Q2Q2×V×C×F
Max./min. voltage Upk Upk2(secondaryoutputoftheVT) Upk2×V
Max./min. current Ipk Ipk2(secondary output of the CT) Ipk2×C
Crest Factor (For procedures, see section 2.7)
The crest factor is defined as the ratio of the peak value of the waveform to the rms value. It is also
referred to as the peak-to-rms ratio.
Peak value
Rms value
Crest factor (CF, peak-to-rms ratio) =
Peak value
Rms value
Input signal waveform
On this instrument, the crest factor is the ratio of the maximum applicable peak value to the
measurement range.
Peak value that can be input
Measurement range
Crest factor (CF, peak-to-rms ratio) =
You can set the crest factor to 3, 6 or 6A. The measurable crest factor is as follows.
{Measurement range × CF setting (3 or 6)}
Measured value (rms value)
Crest factor (CF) =
* However, the peak value of the input signal must be less than or equal to the maximum allowable
input.
If the crest factor of the input signal is greater than the specifications of this instrument (the crest factor
defined at the rated input), you can measure the signal by setting a greater measurement range. For
example, even if the crest factor is set to 3, measurement is possible for signals with a crest factor
greaterthanorequalto5whenthemeasuredvalue(rmsvalue)islessthan60%ofthemeasurement
range.Iftheminimumeffectiveinput(1%ofthemeasurementrange)isbeingappliedwhenthecrest
factor is set to 3, measurement at a crest factor of 300 is possible.
The voltage range, current range, effective input range, and measurement accuracy vary depending
on the crest factor setting. For details, see chapter 7 in the Getting Started Guide, IM WT310E-02EN.
1.2 Measurement Conditions

1-10 IM WT310E-01EN
Measurement Period (For procedures, see section 2.8)
Measurement Period for Measurement Functions Used in Normal
Measurement
The measurement period is determined by the input signal that is used as the reference (synchronization
source). The measurement period is set within the data update interval between the first point where the
sync source crosses the level-zero point (center of the amplitude) on a rising slope (or falling slope) and
the last point where the sync source crosses the level-zero point on a rising slope (or falling slope).
Data update interval:
Measurement period
Synchronization
source
Rising zero crossing
Falling zero crossing
If there is not more than one rising or falling slope within the data update interval, the entire data
update interval is set as the measurement period.
Data update interval:
Measurement period
Synchronization
source
The measurement period for determining the numeric data of the peak voltage or peak current is
always the entire span of the data update interval. Therefore, the measurement period for the following
measurement functions, which are determined on the basis of the maximum voltage or current, is also
the entire span of the data update interval.
Peak voltage (U+pk/U-pk), peak current (I+pk/I-pk), and peak power (P+pk/P-pk)
Fordetails,seeappendix5.
Measurement Period for Measurement Functions Used in
Harmonic Measurement (Option)
The measurement period extends from the first sample in the data update interval for 1024 points,
counted at the harmonic sampling frequency.
This instrument determines the harmonic sampling frequency automatically based on the period of
the signal that is set as the PLL source. The sampling data and measurement period that are used
to determine the values of harmonic measurement functions may be different from those used to
determine the values of normal measurement functions.
Data Update Interval (For procedures, see section 2.10)
The data update interval is the interval at which sampled data is acquired and measurement functions
are computed, displayed, transmitted, and output through D/A conversion.
You can select the data update interval from the options below.
0.1s,0.25s,0.5s,1s,2s,5s,10s,20sorAuto
At each data update interval, the numeric data is updated, stored, converted and output as analog
signals, and transmitted through the communication interface.
When set to Auto, every time a period of the input waveform specified as the synchronization source
is detected, measured data is updated, output as analog signals, and transmitted through the
communication interface.
To capture relatively fast load fluctuations in the power system, select a fast data update interval. To
capture low frequency signals, select a slow data update interval.
If the fluctuation in the input signal period is large, select Auto.
1.2 Measurement Conditions

1-11
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
Input Filters (For procedures, see section 2.9)
There are two types of input filters: the line filter and the frequency filter.
Line Filter
Becausethelinefilterisinsertedintothevoltageandcurrentmeasurementinputcircuits,itdirectly
affects voltage, current, and power measurements (see the block diagram in appendix 7). When the
line filter is turned on, measured values do not contain high frequency components. Thus, the voltage,
current, and power of inverter waveforms, distorted waveforms, etc., can be measured with their high
frequency components eliminated.
Frequency Filter
The frequency filter is inserted into the frequency measurement input circuit and affects frequency
measurements. It also affects the detection of the measurement period for voltage, current, and power
measurements (see appendix 4). In this case, the filter also acts as a filter for detecting the zero-
crossing of the synchronization source signal more accurately. The frequency filter is not inserted
into the voltage and current measurement input circuits. Therefore, the measured values include high
frequency components even when the frequency filter is turned on.
Averaging (For procedures, see section 2.11)
You can take exponential or moving averages of the numeric data. The averaging function is useful
when because of large changes in the power or load or a low input signal frequency, the numeric
display fluctuates and is difficult to read.
Turning Averaging On and Off
Measurement Functions Used in Normal Measurement
 Youcanselectwhethertoaveragevalues.Whenyouenableaveraging(ON),theAVGindicator
illuminates.
Measurement Functions Used in Harmonic Measurement (Option)
• Ifaveragingisturnedon,andtheaveragingtypeisEP(exponentialaveraging),averagingis
performed on harmonic measurement functions.
• Evenifaveragingisturnedon,iftheaveragingtypeisLin(movingaverage),averagingisnot
performed on harmonic measurement functions.
Averaging Types
You can use exponential or moving averages.
Exponential Averaging
With the specified attenuation constant, the numeric data is exponentially averaged according to the
equation below.
D
n=
(M
n
− D
n−1
)
K
Dn−1+
Dn: Displayed value that has been exponentially averaged n times. (The first displayed value, D1, is
equal to M1.)
Dn–1:Displayedvaluethathasbeenexponentiallyaveragedn–1times.
Mn: Numeric data at the nth time.
K:Attenuationconstant(selectfrom8,16,32,and64)
1.2 Measurement Conditions

1-12 IM WT310E-01EN
Moving Average
The specified average count is used to compute linear averages according to the equation below.
D
n=
M
n−(m−1)
+ • • • M
n−2
+M
n−1
+M
n
m
Dn:Displayedvalueofthelinearaverageofmitemsofnumericdatafromthen–(m–1)th to the nth
time
Mn–(m–1):Numericdataatthen–(m–1)th time
………………………………………………
………………………………………………
Mn–2:Numericdataatthen–2th time
Mn-1:Numericdataatthen–1th time
Mn: Numeric data at the nth time
m:Averagecount(selectfrom8,16,32,and64)
Measurement Functions That Are Averaged
The measurement functions that are directly averaged are indicated below. Other functions that use
these functions in their computation are also affected by averaging. For details about how the values
of measurement functions are determined, see appendix 1 in the Getting Started Guide, IM WT310E-
02EN.
Measurement Functions Used in Normal Measurement
• U,I,P,S,andQ
• λ,Φ,CfU,andCfIarecomputedusingtheaveragedvaluesofUrms,Irms,P,S,andQ.
Measurement Functions Used in Harmonic Measurement (Option)
• U(k),I(k),andP(k)
• λ(k)andΦ(k)arecomputedusingtheaveragedvaluesofP(k)andQ(k).
• Uthd,Ithd,Uhdf(k),Ihdf(k),andPhdf(k)arecomputedusingtheaveragedvaluesofU(k),I(k),
and P(k).
k: The harmonic order
Q(k): reactive power of harmonic order k
Measurement Functions That Are Not Averaged
The following measurement functions are not averaged.
Measurement Functions Used in Normal Measurement
 fU,fI,U+pk,U–pk,I+pk,I–pk,P+pk,P−pk,Time,WP,WP+,WP–,q,q+,andq–
Measurement Functions Used in Harmonic Measurement (Option)
ΦU(k),ΦI(k),andfPLL
1.2 Measurement Conditions

1-13
IM WT310E-01EN
Features
1
2
3
4
5
6
7
8
App
Index
1.3 Holding Measured Values and Performing
Single Measurements
Holding Measured Values (HOLD; for procedures, see section 3.1)
You can use the hold operation to stop measuring and displaying the measured data at each data
update interval and hold the display of all measurement function data. The D/Aoutput, communication
output, and other values reflect the held values.
Single Measurement (SINGLE; for procedures, see section 3.2)
While the display is held, the signal is measured once at the data update interval, and then the display
is re-held. If you press SHIFT+HOLD (SINGLE) when the display is not held, measurement restarts
from that point.