Compact Power Meter

Extremely low current measurement to 50 micro-amps
Maximum up to 26 Amps RMS
Yokogawa WT310HC Power Meter


  • Fast display update rate of 100ms
  • Basic accuracy for all input ranges is 0.1% rdg + 0.05% rng (50/60Hz) and DC 0.1% rdg + 0.2% rng.
  • U/I/P/Freq/Integ(+/-)/Harmonics components/ THD with max. 100ms cycle
  • WTViewerFreePlus software can monitor and save the 200 parameters used.
  • Auto ranging function available in selected ranges
  • Bandwidth: DC and 0.1Hz to 100 kHz (WT310EH is up to 20 kHz for 40A).
  • Maximum direct input of up to 600V and 20A, or 40A (incase of WT310EH).>/li>
  • High-speed data update (up to 10 readings per second.)
  • USB, GP-IB or RS-232 (selectable) and Ethernet Modbus/TCP (Optional)
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  • Wide current input ranges
  • Simultaneous measurement of all parameters
  • Fast display and data update rate
  • MAX hold function
  • Line filter and frequency filter capabilities
  • Connectivity of Modbus/TCP*1 with YOKOGAWA’s recorders and Ethernet*1 with PLC
  • D/A output for measurement recording


  • For home appliances and office equipment
  • Production line or QA testing of electric devices
  • Development and evaluation tool for home appliances
  • Testing to international standards, such as IEC62301, Energy Star and SPECpower*1
  • For industrial equipment and transportation
  • Automotive- Battery or DC driven device evaluation
  • Duration testing and efficiency measurement for industrial motors and rotating machinery
  • Conformance and evaluation testing of uninterruptable power supplies (UPS)


The WT310E provides extremely low current measurement capability down to 50 micro-Amps, and a maximum of up to 26 Amps RMS. This instrument is ideal for engineers performing stand-by-power measurements, Energy Star®, SPECpower and IEC62301 / EN50564 testing, battery charger and other low-level power measurements.

  • WT310E has one input element
  • WT310EH has one input element, high current
  • WT332E has two input elements
  • WT333E has three input elements
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Many of today’s power conversion circuits use energy saving switching techniques. These can cause highly distorted voltage or current waveforms with high harmonic content. To measure these waveforms accurately, the WT300E series power meters use high resolution sixteen bit Analog to Digital converters with a digitizing rate of 100 kS/s. They have a new enhanced low frequency measurement capability of 0.1 Hz. Overall bandwidth is DC and 0.1 Hz to 100 kHz,

The WT310EH is a single phase high current version with current ranges from 1 Amp to 40 Amps RMS. The bandwidth on this model is DC and 0.1 Hz to 20 kHz. The WT332E is a two element meter for use on split phase and three phase three wire circuits. The WT333E is a three element meter for use on three phase three wire or three phase four wire circuits. These models have current ranges of 0.5 Amps to 20 Amps RMS, with low current measurements to 5 mA. All models have voltage ranges from 15 to 600 Volts RMS, and low voltage measurement capability to 150 mV. An optional Harmonic Analysis function is available for the WT300E series Digital Power Meters. This will benefit the design and test engineer in product performance evaluation and for power quality conformance testing. Both the Normal power parameters and Harmonic data are measured simultaneously providing for faster and more accurate power analysis. Harmonic Analysis and THD Calculations can be made up to the 50th order from a 50 or 60 Hertz fundamental frequency.

The Integration function measures Amp-Hour and Watt-Hour parameters. This is especially important for stand-by-power measurements. In the stand-by mode the current can be very low. Then when the device goes to operation mode, the current can increase substantially. The new Auto Range feature will optimize the range setting for maximum accuracy measurements. Yokogawa’s “Average Active Power” function makes it possible to measure power consumption under conditions where the power fluctuates greatly. Watt-Hours are measured over some time period then the Time is divided out to leave an average power reading. This is the industry preferred method for Stand-by-Power measurements.

A new feature has been added to the data update rate. The WT300E series can chase fluctuating input frequencies like motor by changing the data update rate automatically. It can cover from the lowest 0.1 Hz input. Users can select “AUTO” data update rate added to fixed settings of the previous models. It can detect cycles of input signal automatically and measure it correctly.

All the industry standard communication interface ports such as USB, GPIB, RS232 and Ethernet are available for the WT300E series. The standard interface is USB plus GPIB or RS232. Ethernet is an available option. Measured digital data from the WT300E series can be acquired by Yokogawa recorders via Ethernet or Modbus/TCP directly. Yokogawa’s WTViewerFreePlus software is provided with each WT300E unit. This permits displaying and saving the measurement data, numeric values, waveform display and trend graphs. Also IEC62301/EN50564 software for stand-by-power measurements is available as a free download.

The WT300E series represents over 30 years of reliability and innovation in the compact power meter segment. With the widest range of quality power measurement solutions, users can be confident that Yokogawa always provides the right solution for their needs. All Yokogawa Power Meters and Power Analyzers are covered by a three year warranty.

  • Literature
  • Specifications
  • Applications
  • Software
  • Accessories
Model: Yokogawa WT300E Series Power Meter
Model WT310E
Voltage Measurement Range Crest factor 3: 15 V/30 V/60 V/150 V/300 V/600 V
Crest factor 6 or 6A: 7.5 V/15 V/30 V/75 V/150 V/300 V
Current Measurement Range Direct Input, Crest Factor 3: 5 mA/10 mA/20 m
Direct Input, Crest factor 6: 2.5 mA/5 mA/10 mA/25 mA/50 mA/100 mA/ 0.25 A/0.5 A/1 A/2.5 A/5 A/10 A
External Current Sensor Input, Crest factor 3: EX1: 2.5 V/5 V/10 V or EX2: 50 mV/100 mV/200 mV/500 mV/1 V/2 V
External Current Sensor Input, Crest factor 6/6A: EX1: 1.25 V/2.5 V/5 V or EX2: 25 mV/50 mV/100 mV/250 mV/500 mV/1 V
Active Power Accuracy: DC: +/-(0.1% of reading + 0.2% of range)
0.1 Hz ≤ f < 45 Hz: +/-(0.3% of reading + 0.2% of range)
45 Hz ≤ f ≤ 66 Hz: +/-(0.1% of reading + 0.05% of range)
66 Hz < f ≤ 1 kHz: +/-(0.2% of reading + 0.2% of range)
1 kHz < f ≤ 10 kHz: +/-(0.1% of reading + 0.3% of range) ±[{0.067 × ( f – 1)}% of reading]
10 kHz < f ≤ 100 kHz: +/-(0.5% of reading + 0.5% of range) ±[{0.09 × ( f – 10)}% of reading]
Frequency measurement range: DC, 0.5 Hz to 100 kHz
Frequency range: Auto switching among six types: 1 Hz, 10 Hz, 100 Hz, 1 kHz, 10 kHz, and 100 kHz
Frequency Filter: Select OFF or ON (cutoff frequency of 500 Hz).
Accuracy: (input signal level is 30% or more of range If crest factor is set to 3. (60% or more if the crest factor is set to 6 or 6A) Frequency filter is ON when measuring voltage or current of 200 Hz or less. +/- (0.06% of reading)
Display: 7-segment LED, 4 items
  GP-IB Interface or Serial (RS-232) Interface (standard)
USB PC Interface (standard)
Ethernet Interface (optional)
Warm-up Time: Approx. 30 minutes
Power supply: 100 VAC to 240 VAC rated, permitted 90 VAC to 264 VAC, rated 50/60 Hz, permitted 48 to 63 Hz
Power consumption: 50 VA
Operating Temperature: Temperature: 5°C to 40°C
THumidity: 20%RH to 80%RH (No condensation) Elevation: 2000m or less
Storage Temperature: Humidity: 20% RH to 80% RH (No condensation)
Dimensions (excluding protrusions): Approx. 213 (W) × 88 (H) × 379 (D) mm
Weight: Approx. 3 kg
Battery backup: Setup parameters are backed up with a lithium battery.

Production line or QA testing of electric Devices

  • Compact half rack mount size helps customers build smaller test systems with a better Return on Investment (ROI)
  • D/A output function for data recording
  • Multiple communication interfaces. USB, RS-232 or GP-IB and Ethernet capability.

The simultaneous measurement of power consumption parameters such as U, I, P, frequency, power factor and harmonics for production line or QA testing, results in reduced tact times, thereby, reducing time and cost of testing. The D/A outputs and communication interfaces enable data to be remotely and flexibly captured. *“Modbus/TCP” function is available with the Ethernet (/C7) option.

Evaluation of large current equipment such as Induction Heaters/Cookers

  • Direct high current measurement up to 40Arms without using external current sensors (WT310HC).
  • Auto ranging function for Integration mode

The WT310EH allows 40 Arms to be directly connected to the input without the requirement to use current clamps or current sensors. This not only provides more precise measurement but also saves on investment costs. The wide current ranges are from 1 A to 40 A and voltage ranges are from 15 V to 600 V. Users can use it to evaluate special waveform driven devices such as, IH cookers and heaters.

Testing to international standards, such as IEC62301, Energy Star and SPECpower

  • The WT310HC has a high measurement resolution of Max. 100μW under the 5mA range setting.
  • Simultaneous measurement of normal power parameters, harmonic components and THD.
  • Dynamic input capability of crest factor Max 300 (Peak value / minimum effective RMS value)
  • Free PCM software for IEC62301 testing

The WT310HC together with the power consumption measurement (PCM) software enables users to perform standby power testing according to international standard

Automotive – Battery or DC driven device evaluation

  • Accurate DC measurement: 0.3% total
  • Direct high current measurement up to 40A without any external current sensor
  • Charge/Discharge (+/-Wh, +/-Ah) energy measurement for batteries

Duration testing and efficiency measurement for industrial motors and rotating machinery

  • Integration measurement for long period
  • D/A output function for data recording
  • DC, 0.5Hz to 100kHz broad bandwidth capability

The WT300E series provides reliable current integration (Ah) and Energy (Wh) measurement for up to 10,000 hours (approx. 1 year). The D/A option is used to save and monitor the measurement results (WT310HC/WT310HCHC: 4ch, WT332/WT333: 12ch). An external recorder or data logger like, a ScopeCorder, can be used to save this D/A function data along with other parameters such as temperatures, torque and rotation speed.

Conformance and evaluation testing of uninterpretable power supplies (UPS)

  • Maximum order setting for THD calculations
  • Efficiency measurements using a single power meter
  • Average active power measurement under integration Mode

The WT300E series enables users to conduct conformity tests according to UPS performance testing standards. The WT300E series is used to measure and calculate input & output levels, the efficiency, frequency and THD. The average active power data also provides accurate values of power consumption. The WT300E series along with the WTViewerFreePlus software helps to simultaneously measure all the necessary parameters required to test a UPS thereby reducing the evaluation time.

Power Consumption Measuring Software

WTViewer is a software program that reads measured numerical, waveform, and harmonic data. Data can be transferred to a personal computer via GP-IB, Ethernet, or USB communications to display and store numeric or waveform data. A communications option can be installed in the WT300E as needed.

  • Waveform Display Measured data of input elements 1 to 3, and PΣ can be displayed on the PC screen via communication
  • Waveform Display Voltage and current waveforms can be monitored on the PC screen.
    You can confirm the voltage and current waveform shapes, waveform distortion, and other phenomena

WT300E Series Sample Program

These are sample program of Visual Basic, Basic net and C# for Communication interface GP-IB, Ethernet and USB for WT300 Series.

WTViewerFreePlus for WT300E Series (included)

The WTViewerFreePlus software can capture measured numeric values, harmonic values, and waveform data. The data can be transferred to a PC via a USB, GP-IB/RS-232 or Ethernet communication interface, and it can be displayed and saved onto the PC.

USB Drivers for WT300E Series

the USB Driver is needed when required by the software.

LabVIEW Drivers for WT300E Series

Data acquisition possible using LabVIEW. LabVIEW drivers can be downloaded from Yokogawa Web site. (free)

Free Download links from Yokogawa

Download free software from Yokogawa

Download Energy Star free software from Yokogawa

Adapter Sets, Leads
758917 —Measurement lead — Qty 1 75 cm, two leads (red and black) in a set
758921 —(Fork terminal adapter set) — Qty 1 4 mm fork terminal, banana terminal conversion, red and black (one each)
758922 — Alligator clip adapter (rated for 300 V) — Qty 1 Banana–alligator conversion, two in a set
758923 — Safety terminal adapter — Qty 1 (spring-hold type) Two adapters to a set.
758924— Conversion adapter — Qty 1 BNC-banana-jack(female) adapter
758931 — Safety terminal adapter — Qty 1 (screw-fastened type) Two adapters to a set. 1.5 mm hex Wrench is attached
  B9284LK —External sensor cable — Qty 1 Current sensor input connector. Length 0.5m
  705926 Connection Cable; Qty 1
  701959 Safety mini-clip (hook type) Set contains one black and one red clip. 1000 Vrms-CAT II.
arrow 701961 — Deluxe Instrument Cart — Qty 1 Deluxe Cart
arrow 701962 — General-purpose Instrument Cart — Qty 1 General-purpose Cart
arrow 7511533-E4 — Rack Mount Kit — Qty 1 For EIA
arrow 7511534-E4 — Dual Rack Mount Kit — Qty 1 For EIA