WT1800 High Performance Power Analyzer (DISCONTINUED)

Notice: This product was discontinued on Dec 29, 2017. See this replacement product:

The WT1800 offers innovative measurement functions for testing product efficiency and the design of inverters, motor drives, lighting systems, uninterpretable power supplies, aircraft power systems, transformer testing, and other power conversion devices. Although the WT1800 is still available, the newer WT1800E offers higher accuracy power measurement.

Yokogawa Special Offers and Product Discounts

Many features are available that are a first in the power measurement industry *1

Measurement - High-precision, wide range, fast-sampling, simultaneous harmonic measurement

Voltage and current frequency bandwidth 5 MHz (-3 dB, typical)

WT1800 Features1Faster switching frequencies increasingly require measurements in a wider range. The WT1800 provides a voltage and current frequency bandwidth (5MHz) 5-fold wider than the previous measurement range and is capable of more correctly capturing fast switching signals.


Reduction of low power-factor error to 0.1% of apparent power (2/3 of previous model)

WT1800 Features2 1A power-factor error is one of the important elements to ensure high-accuracy measurements even at a low power factor. The WT1800 has achieved a power-factor error (0.1%) that is 2/3 of the previous model, in addition to a high basic power accuracy of ±0.1%.


Wide voltage and current range allowing direct input

WT1800 Features3Direct input of measurement signals makes it possible to measure very small current that can hardly be measured with a current sensor. The WT1800 provides a direct input voltage range from 1.5 V to 1000 V (12 ranges) and a direct input current range from 10 mA to 5 A (9 ranges) or from 1 A to 50 A (6 ranges).


0.1 Hz low-speed signal power measurement and max. 50 ms high-speed data collection

WT1800 Features4The frequency lower limit has been reduced to 0.1 Hz from the previous 0.5 Hz (5-fold lower than the previous model) to meet the requirement for power measurements at a low speed. Furthermore, high-speed data collection at a data update rate of up to 50 ms has been inherited. In addition to normal measurement data, up to the 500th order harmonic data can be measured and saved simultaneously. The data update rate can be selected from nine options from 50 ms to 20 s.
* Harmonic measurement at the 50 ms data update rate is possible up to the 100th order.


Particular voltage and current range selectable

WT1800 Features5Wide voltage and current input ranges have the advantage of extending the measurement application range. However, the downside is that the response time of the auto range tends to slow down. A range configuration function solves this problem. Since only the selected range (effective measurement range) can be used, the range can be changed up or down more quickly.

* Comparison with Yokogawa's previous model WT1600

*1: Applicable to a general-purpose high-precision three-phase power analyzer as of February 2011 (according to Yokogawa's survey).

Support for Energy Conservation Technologies and Sustainable Energy Development

WT1800 Dual

Dual Harmonic Measurement
The perspective of the efficient use of energy is boosting demand for inverters to convert 50Hz or 60 Hz AC power to DC power, grid connection controllers to control reverse power flow occurring due to excess power, and battery chargers/dischargers. The WT1800 is capable of simultaneously measuring the harmonic distortion of the input and output current of these devices. Challenging the common wisdom that "harmonic measurement is limited to a single line," the WT1800 is capable of performing two-line simultaneous harmonic measurements. The WT1800 is also capable of measuring up to the 500th order harmonic even at high fundamental frequencies such as a 400 Hz frequency.



New functions greatly support power measurements

Dual harmonic measurement (option)

WT1800 Features5The industry's first two-line simultaneous harmonic measurement is available, in addition to simultaneous measurement of harmonic and standard measurement items such as voltage, current, and power values. Previously, harmonic measurements of input and output signals
had to be performed separately. With the WT1800, harmonic measurements of input and output can be performed simultaneously.

Two-channel external signal input is available for power measurement and analog signal data measurement

WT1800 Functions1(option available in combination with the motor evaluation function) Power measurements can be performed together with physical quantity data such as solar irradiance or wind power in wind generation.

Electrical angle measurement is also supported.

WT1800 Functions2Motor evaluation function allowing A-phase, B-phase, and Z-phase inputs (option available in combination with external signal input) Pulse or analog signals can be input for rotation speed and torque signal measurements. The motor evaluation function of the WT1800 makes it possible to detect the rotation direction and measure the electrical angle, which is not possible with Yokogawa's previous model.

High Speed Data Capturing (option)

WT1800 HighSpeedDataA New High Speed data capturing /HS option can measure ∑Urms, ∑Irms and ∑P from single phase (DC signal) and three phase devices every 5 ms (When external syncronisation is OFF) or, 1 ms to 100 ms when External Sync is ON (depending on the frequency of the clock signal ).
It outputs data in 1 s blocks to internal/external memory or to a PC through a communications interface.
Existing products can measure three phase power values every 50ms however, a 50ms data update rate is typically insufficient to be able to analyze motor start up transients or the turn-on behavior of devices.

High Resolution Display

All Data of 6-input, Single/Three-phase Devices can be Viewed on a Single Screen
Important Information is Displayed in a Concentrated Format on High Resolution 8.4-inch XGA Display

A high resolution display with a resolution about 2.6-fold higher than Yokogawa's previous model* is employed. More setting information and measurement data can be displayed


*Comparison with Yokogawa's previous model WT1600


Measurement data can be displayed on a single screen, along with the respective detailed setting information of 6 inputs, such as a voltage range, current range, synchronization source, wiring system, and filter. You do not need to switch display screens frequently to confirm the settings.

WT1800 6Element 1

With the WT1800, the data update rate can be selected from 9 options from the fastest data update rate of 50 ms to an update rate of 20 s for low-speed measurements. For example, if you want to save the average data at a 1-minute interval and inappropriately set the update rate of 50 ms, measurement results may be not correct because data can be saved only at a 1-minute interval (once every 20 times).Such a risk can be avoided by setting the update rate that is suited to the interval at which you want to save data.

Computation Range Display

Direct display of primary current values

WT1800 Computation

The setting ranges of voltage and current are usually displayed with voltage and current signal levels that are input to the power analyzer. The WT1800 provides not only this direct display but also added a new computation range display function to the external current sensor range. This function allows you to display the primary current range for the voltage output type current sensor. It allows you to intuitively set a range that is suited to the primary measurement signal level.

User-defined event function

Capture only a particular event

WT1800 User Defined

The data saving function of the WT Series is capable of continuously saving data for a long period of time. However, to check an irregular event, data must be retrieved using spreadsheet software. The event trigger function allows you to set the high and low limits and only trigger data that falls into or out of that range to be saved.

Individual Null Function

Function to reset only a particular input signal to zero

WT1800 Null Function

A null function allows you to reset the offset value to zero in the connected state. Previously, all inputs could only be collectively set to ON or OFF. With the WT1800, the null value for each input can be set to ON, HOLD, or OFF. In a motor evaluation test, the offset value for only a particular input can be reset to zero. This makes it possible to perform a more accurate motor evaluation test.

Help Function

Display the manual on the screen

WT1800 Help Function
English help menu supports measurement

Display the manual on the screen Frequently used functions (keys) can be performed without the instruction manual. You may, however, want to use a new function during evaluation. The WT1800 includes a built-in instruction manual on the functions, so if a new operation is required, you can read the explanation of the function on the screen.

Line Filter

Capture an original signal masked by high frequency component

WT1800 Line Filter 1WT1800 Line Filter 1a

WT1800 Line Filter 2WT1800 Line Filter 2a

WT1800 Line Filter 3WT1800 Line Filter 3a

WT1800 Range Config 1

A new range configuration function is available. It allows you to choose a particular voltage and current input range (effective measurement range). Eliminating unnecessary ranges has made it possible to achieve optimal range setting that is faster than Yokogawa's previous model*. This allows more quicker tracking of signal changes. If the peak goes over the limit, you can switch to a preset range. This is effective in reducing the production time for a repeat test, such as setting to OFF, 100 V, OFF and so on, which is performed frequently on the production line.

Numerical and harmonic bar graphs

Dual Harmonic Measurement

WT1800 Dual Harmonic

A harmonic measurement option (/G5) makes it possible to display both numerical data and bar graphs to help understand measurement data visually. In addition, a dual harmonic measurement function (/G6) makes it possible to measure and display two-line harmonic bar graphs (dual harmonic) simultaneously.


Support for 6 split screen displays

WT1800 Waveform

A high resolution display makes is possible to split the waveform display into up to 6 split screens. This makes it possible to split the display of signals between the input and output of a three-phase inverter and display them simultaneously. Waveform display allows you to display waveforms for the voltage alone or the current alone, or arbitrarily set the display position, so you can also display only the signals you want to compare one above the other.

Dual Vector

Simultaneous two vector displays

WT1800 Dual Vector

Fundamental harmonic voltage and current signal phase vectors can be displayed. With Yokogawa's previous model, vector display is limited to a single line. With the WT1800, Dual vectors can be displayed. In addition, combination display of vectors and numerical values is also possible. This allows you to view the numerical parameters and voltage and current phase status visually.


Capture efficiency changes visually

WT1800 Trend

When evaluating inverter efficiency, sometimes small efficiency changes can hardly be recognized with just numerical values. Trend display makes it possible to display measurement values and measurement efficiency as trend data in time series to help capture even small changes visually. Trend data over several minutes or several days can be displayed.

Setting Information

Combination display of information and numerical screens

WT1800 Setting

The screen can be split into two, with one above the other, and two types of screens can be displayed simultaneously. Screen can be selected from Numerical, Waveform, Trend, Bar Graph, and Vector displays. Another new function allows you to press the NFO button on the Numerical screen to display the setting information in the upper row and automatically scale down the numerical nformation displayed in the lower row.


Customize display screen

WT1800 Custom

Image data can be loaded onto the screen and the position and size of the numerical data can be specified.
The display screen can be customized so that the corporate logo of your company is displayed on the screen, or only the measurement items you want to view, such as input and output efficiency or frequency, are displayed one above the other.

*The data for the created screen needs to be loaded from a USB storage device.

September 9, 2016

  • Released new firmware version 2.42
Model Description
WT1801 One Input Element with USB, GPIB and Ethernet Interface
WT1802 Two Input Element with USB, GPIB and Ethernet Interface
WT1803 Three Input Element with USB, GPIB and Ethernet Interface
WT1804 Four Input Element with USB, GPIB and Ethernet Interface
WT1805 Five Input Element with USB, GPIB and Ethernet Interface
WT1806 Six Input Element with USB, GPIB and Ethernet Interface

Energy consumption in low-power and standby modes is an important issue due to increased awareness that energy resources are becoming limited and demand for energy-saving household electrical appliances continues to grow. IEC62301 Ed2.0 (2011) and EN 50564:2011 define standby mode as the lowest energy consumption of an appliance not performing its main function, when connected to the mains. IEC62301 Ed2.0 (2011) defines test methods and requirements for both the mains supply and the test equipment. It is crucial that design and test engineers choose highly accurate power measurement tools to confirm that their devices meet these requirements.


With increased focus on reducing energy consumption and compliance with efficiency standards, this app note provides an overview on the types of measurements needed for efficiency and power quality, and the instruments that take them.


Designing an instrumentation system for high current measurement requires careful consideration of the trade-offs associated with each type of sensing device. The purpose of this application note is to help engineers understand the sensing choices available and the corresponding trade-offs with each technology.


This white paper describes the WT1800, a precision power analyzer that has been replaced by the WT1800E, a unit with numerous improvements including better accuracy. Please visit the WT1800E product page to learn more about the WT1800E.

To keep pace with the increasing speed of switching devices in inverters, Yokogawa has developed the WT1800 precision power analyzer with 10 times faster sampling speed and 5 times wider frequency bandwidth compared with previous models. Its basic accuracy is 0.15% and the frequency bandwidth of voltage and current is 0.1 Hz to 5 MHz (-3 dB, Typical) including the DC component. With up to six inputs, a single WT1800 unit can measure the efficiency of three-phase inverters. In addition, the high-speed data capturing mode allows the WT1800 to measure transient power. This paper describes the high-speed, real-time power measurement technologies underlying these functions.


The objective of this paper is to show the close relationship between efficiency and power quality, and provide education on the causes of power quality, types of power quality issues, and provide guidance on measurement considerations.


Although WTViewer is not officially supported under the Linux environment, users have successfully done so using WINE (flavor of Linux) via RS232. For connectivity to WT210/WT230, WTViewer requires that the meter be set ...

Yes, you can use DL Term with the WT1800 using an Ethernet (VXI-11) or USB connection.
  • Current Knobs and Pads (Studder) Used on the Direct Input Terminals of the WT500 Part Numbers
  • A9105ZG: Black Current Knob Set of 2 B9292GX: Pad (Studder) Set of 10

The AC Power Input in all Yokogawa instruments is designed as a 3-pin connection (one of which is a GND pin). In some parts of the world, PCs are sold with AC power cables that are 2-pin. Often times this means the ...

  • WT1800 High Performance Power Analyzer, WT500 STORE functions can only be used to record NUMERIC data   
  • WT1600, WT3000 STORE functions can be used to record both NUMERIC and WAVEFORM data
Yes, the AUX inputs on the WT1800 can be used in the Math functions.   For example, if you wanted to measure a DC bus input using the AUX inputs (input elements not connected), you would scale one of the AUX inputs to ...
The WT1800 and WT3000 series digital power analyzer offer two calculation methods, Type1 and Type3, for apparent and reactive power.  Type1:The WT will first calculate the RMS voltage Urms, current Irms, and active ...

The following product tutorial guides have been created for the WT and PZ Series Power Meter and Analyzer instruments and are available for download. Each tutorial contains quick and easy steps to help you get started ...


The following may be causing the problem. 5V may have occurred during rating. Check the range setting again. DA output error can affect the values when the input is smaller than the rating. Have you checked the error ...

The input terminals on all Yokogawa power meteras are located on the rear panel. This takes into account safety when handling the measuring instrument.    The signal input to the power meter normally carries high ...
  • Power analyzers/power meters
  • Binding posts on the direct current input terminals
  • Prevent an open current circuit and safety hazards
A quick and simple way of accessing the measurement data from a CSV file saved by the WT1800 is to use the MATLAB import wizard. In MATLAB, simply click on File > Import Data.... You can also use the MATLAB built-in ...

To use USB interface on the WT500 and WT1800 Power Analyzer from NI LabVIEW environment, you will need to use the USB driver from National Instruments. This USB driver is usually installed when you install NI-VISA and is called the ...

To measure inrush current on the WT1800, you will need to define and use the IPPEAKMAX() user defined function in combination with the Max Hold feature. A complete tutorial with instrument settings and how-to procedures ...
The WT1800 allows you the ability to create and load your own custom display for special application needs. You will not only be able to generate your own custom background but you will be able to change the displayed ...
In the manual IM-WT1801-01EN, the following sentences are written. Fundamental Measurement ConditionsAll the settings for the fundamental measurement conditions for high speed data capturing are the same as those for ...

To programmatically read all 500 harmonic orders measurement values, please use the ":NUMERIC:LIST" command set. The maximum number of items for the :NUMERIC:LIST:VALUE? command is 64.  However, 1 LIST ITEM can ...


 You can not use LabVIEW and WTviewer to communicate with the PC using same USB driver. The USB driver for LabVIEW and the USB driver for WTviewer is different. Yokogawa's YKMUSB driver is used by WTviewer ...

There are several items you will need to check and verify to solve this issue. Verify the GP-IB connectionSome instruments have a D/A output connector located next to the GP-IB connector. There have been some ...
This could be caused by any of the following: Is there any crosstalk (especially around the 2nd order)? Are there any effects of CMRR (especially around the 2nd order)? Is the location of measurement immediately next ...

The difference in measurement values can be attributed to the difference in calculation methods for normal mode and harmonic mode.   The voltage, current, and power in normal mode are displayed as the total of the ...


The peak value and crest factor may be unstable if they have not been captured accurately. If the peak value is not stable, neither will the crest factor be stable. The cause is the difficulty in capturing the narrow ...

Output function: HArWhen the default output item is set to 1, the printout time for up to the 50th order is about 116 seconds. The printout time for up to the 25th order is about 75 seconds. Output function: HArWhen the ...

The waveform may actually not be a pure sine wave. Even though a 50/60 Hz sine wave is expected, the following factors may be involved: The waveform is slightly distorted (harmonic components are mixed in) Small ...

  • Check the "Sync Source" and zero cross filter (frequency filter) settings.
  • For the WT3000, "Sync Source" setting is irrelevant if the data update rate is 250 ms, 500 ms, 1 s, or 2 s.

Check for differences in the specifications or features of the instruments. For values that do not match when inputting a 50/60 sine wave Check whether the value is within the specifications (error) of each power ...


The measurement intervals of the measured I/O data must overlap exactly. Check the sync source setting. For example, route the input to a three-phase device under measurement to input elements 1-3 on the power meter, ...


Check for differences in the specifications or features of the instruments. For values that do not match when inputting a 50/60 sine wave Check whether the value is within the specifications (error) of each power ...

  • Power Analyzer/Power Meter 
  • In the case of three-wire, or 3V3A wiring, or three phase power source, they do not match because it is the line to line voltage that is measured
In the three-phase three-wire, or 3V3A wiring scheme, the phase angle of voltage between each input element is 60 degrees because it is the line to line voltage that is measured. Please download and refer to the ...

In the three-phase three-wire, or 3V3A wiring scheme, the phase angle of voltage and current input to each input differs from that of the actual load because it is the line to line voltage that is measured.  In ...

This is due to measurement and calculation error, or differences in calculation methods.   On the WT, the three-phase apparent power (ΣS) equation is calculated under the assumption of a balanced condition (the ...
When measuring input signals of distorted waves, signals that are DC-offset or signals that include superimposed harmonic components, will result in different values for power factor and phase angle than those expected ...
  • WTViewer Save Setting feature will only save WTViewer setting information
  • Will NOT save the setting information of the instrument

Check the Synch Source and Frequency Filter settings When a single-phase signal being measured fluctuates around power factor of 1.Slight fluctuations in the measured values of voltage, current, and power can cause a ...


This comprehensive training module covers the following topics:

  • Introduction & Product Familiarization
  • Basic Setup, System & Wiring Configurations
  • Basic and Advanced Analysis Features

This training module covers the following topics:

  • Introduction & Installation
  • Connecting to Instrument
  • Setup, Measure, and Analyze
  • File Operations: Saving and Loading Data
  • Video Demonstrations

As the manufacturer of the world's first drone to combine Vertical Take Off and Landing (VTOL) and forward flight, ATMOS UAV needed to perform highly accurate motor system testing, while keeping the test time as short as possible. Discover how Marlyn exceeded all expectations in terms of reliability and was successfully launched in an extremely competitive market.


In the paper published on OpenUCT, a Cape Town University researcher uses a Yokogawa Test&Measurement High-Performance Power Analyzer to record instantaneous voltage and current of a three-phase, four-wire system.


In a research paper published on the website IEEE Xplore, researchers from Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), University of Wisconsin-Madison, use a Yokogawa Test&Measurement WT1806 High-Performance Power Analyzer to measure the efficiencies of inverters used in the research.


In a research paper published on IEEE Xplore, researchers from Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), University of Wisconsin-Madison, use a Yokogawa Test&Measurement WT1800 High-Performance Power Analyzer to measure the losses and efficiencies of two inverters.


In a research paper published on IEEE Xplore, researchers from General Motors Global Propulsion Systems and Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), University of Wisconsin-Madison, use a Yokogawa Test&Measurement WT1800 High Performance Power Analyzer and PX8000 Precision Power Scope for high-stability measurements of voltage, current, and power loss.

Product Overviews




    Why should you be concerned with your product’s power system voltage and current harmonics? From an engineering perspective, harmonics produce excessive heat in equipment that causes significant damage and results in inefficient operation. From a business perspective, compliance is an absolute requirement for entry into global markets. To minimize or eliminate these issues and establish acceptable levels of harmonics, numerous power quality standards with specifications and limits for harmonic distortion, such as IEEE 519-2014 and IEC61000-3-2, have been introduced. During this webinar, attendees will gain knowledge on the inner workings of harmonics, learn best practices for accurately measuring harmonics, learn to recognize and distinguish the critical difference between DFT and FFT, and discover important measurement tradeoffs across various test equipment.


    You know the basics of electrical power measurements, have set up your dyno, and made key measurements – which is great. But as your motor and drive projects progress, the complexities of system drive requirements can change frequently. Control algorithms, networked communications, and mechanical systems form a complex web of interactions that need sorting. This 60-minute webinar explains how to get past ground-level measurements and delve into comprehensive solutions that leverage test and measurement instruments including power analyzers, high-speed data acquisition, and real-time software.

    Topics include:

    • How to avoid the “gotcha's” of inverter-based measurements
    • Computations for field-oriented control
    • The integration of CAN bus communications
    • Correlations in the frequency domain
    • Other advanced motor and drive topics

    The technical presentation includes an audience Q&A.

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