WT300E Series Digital Power Meter

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.



The WT300E's wide range of functions and enhanced specifications, allows handling of all the measurement applications from low frequency to high frequency inverters using a single power meter.

Accuracy with fast display and update rate: 
The WT300E series with the fast display update rate of 100ms, offer’s engineers a short tact time in their testing procedures. The basic accuracy for all input ranges is 0.1% rdg + 0.05% rng (50/60Hz) and DC 0.1% rdg + 0.2% rng.

Simultaneous Measurement:

U/I/P/Freq/Integ(+/-)/Harmonics components/ THD with max. 100ms cycle.

In addition to standard power measurements, the WT300E series measures all DC and AC parameters. Additionally, the WT300E series can measure harmonics and perform integration simultaneously without changing the measurement mode. The accompanying WTViewerFreePlus software can monitor and save the 200 parameters used. 

Auto ranging function available in selected ranges.

The auto-range function is used to select or change the ranges automatically, within specified ranges. This results in shorter range changing times, allowing more efficient testing.

3 Input Signal Change

Auto Ranging Function For Integration MeasurementTypically, when power meters operate in an integration mode to measure power consumption and standby power, the measuring ranges need to be fixed. However, if the level of the input exceeds the maximum of the selected range, the test will need to be repeated. The WT300E Series has a high-speed automatic ranging capability in integration mode, which removes the need to repeat any test.

Bandwidth: DC and 0.1Hz to 100 kHz (WT310EH is up to 20 kHz for 40A).

Direct Input: Maximum direct input of up to 600V and 20A, or 40A (incase of WT310EH). The wide current input ranges on the WT310E series, give users the option to measure current as low as 50 micro-Amps to as high as 40Arms (incase of WT310EH).

High-speed data update (up to 10 readings per second.)

Comparison Table

Enhancement points from the WT310/WT330 

Changed points from the WT210/WT230

WT300E Series
WT300 Series
Basic power measurement accuracy (50/60 Hz)  

0.1% of reading + 0.05% of range 

0.1% of reading+0.1% of range
0.1% of reading+0.1% of range
Influence of power factor When power factor (λ)= 0 (S: apparent power) ±0.1% of S for 45 Hz ≤ f ≤ 66 Hz When power factor (λ)= 0 (S: apparent power) ±0.2% of S for 45 Hz ≤ f ≤ 66 Hz When power factor (λ)= 0 (S: apparent power) ±0.2% of S for 45 Hz ≤ f ≤ 66 Hz
Frequency bandwidth  
DC, 0.1 Hz to 100 kHz (WT310EH DC, 0.1 Hz to 20 kHz)
DC, 0.5 Hz to 100 kHz (WT310H DC, 0.1 Hz to 20 kHz)
DC, 0.5 Hz to 100 kHz
Direct input current range  
WT310E: 12 ranges/5 mA to 20 A, WT310EH: 6 ranges/1 to 40 A WT332E/WT333E: 6 ranges/0.5 to 20A
WT310: 12 ranges/5 mA to 20 A, WT310HC: 6 ranges/1 to 40 A WT332/WT333: 6 ranges/0.5 to 20A
WT210: 12 ranges/5 mA to 20 A, WT230-2ch/WT230-3ch: 6 ranges/0.5 to 20A
External current input  

EX1:2.5/5/10[V] EX2:50m / 100m / 200m / 500m / 1 / 2[V](OP)

EX1:2.5/5/10[V] EX2:50m / 100m / 200m / 500m / 1 / 2[V](OP)
EX1: 2.5/5/10[V] EX2:50m / 100m / 200m / 500m / 1 / 2[V](OP)
Expansion of effective input range for voltage & current (CF=6A)  
2% to 260%*1
Expansion of maximum displaying value for voltage & current (CF=6A) 2% to 260%*2  
Simultaneous measurement of RMS, Voltage MEAN & DC  
Frequency measurement  
2 channels (voltage & current)
2 channels (voltage & current)
Selected voltage or current (one)
Number of display item  
4 items
4 items
3 items
Sampling rate  
Approximately 100 kS/s
Approximately 100 kS/s
Approximately 50 kS/s
Data update rate  
100m/250m/500m/1/2/5/10/20 sec, Auto
100m/250m/500m/1/2/5 sec
100m/250m/500m/1/2/5 sec
Harmonic measurement  
Yes (OP/G5)
Yes (OP/G5)
Yes (OP/HRM)
THD calculation maximum order setting  
Yes (OP, 1 to 50th)
Yes (OP, 1 to 50th)
Auto ranging of integration  
Communication Interface USB  
GP-IB Yes GP-IB or RS-232 Yes GP-IB or RS-232 No
RS-232 Yes GP-IB or RS-232 Yes GP-IB or RS-232 Yes (OP) GP-IB or RS-232C
Ethernet Yes (OP) Yes (OP) Yes (OP) GP-IB or RS-232C
Modbus/TCP (Ethernet) Yes (OP,/C7) No No
IEEE standard for GP-IB IEEE488.2 IEEE488.2

IEEE488.1 or IEEE488.2

Comparator function Yes Yes Yes
Viewer software (setting & data capturing) Free (included) Free (included) Free (download)

*1: WT310EH input range is 2% to 260% (20 A range only up to 200%)
*2: WT310EH input range is 2% to 280% (20 A range only up to 220%)
*3: Simultaneous, mode independent measurement using the WTViewerFreePlus PC software
*: A command compatible mode for the previous WT200 series is available. (IEEE488.2 only) In that mode, the WT300E series and WT300 series works identically to a WT200 series except for the Store (and recall operation) and the Compare functions.
*: Modbus/TCP communication requires /C7 Ethernet option.


The WT300E series offers a wide range of communication interfaces such as USB, GP-IB or RS-232 (selectable) and Ethernet Modbus/TCP (Optional)

Wide current input range

  • Wide current input ranges: The WT300E series covers a broad range of current inputs, from few mA up to 40 A rms. Both AC and DC waveforms can be measured.
  • WT300E Lineup

  • Simultaneous measurement of all parameters: The WT300E can measure all DC and AC parameters. The WT300E series can also measure harmonics and perform integration simultaneously without changing the measurement mode.
  • Fast display and data update rate: The fast display and a maximum data update rate of 100ms on the WT300E series, offers a short tact time in testing procedures. 
  • MAX hold function: The maximum values of RMS/PEAK Voltage & Current, Active Power, Reactive Power and Apparent Power can be held.
  • Line filter and frequency filter capabilities: These filter functions will cut off unnecessary noise & harmonic components for fundamental waveform measurements.

Users therefore have the flexibility to choose a variety of settings according to their application needs e.g. from production lines to engineering test benches. Users can use WTViewerFreePlus software to set up all basic and advanced measurements. Additionally, the numeric values, waveform display* and trend graphs of the measurement data can be displayed and saved.

*Waveform display requires the /G5 Harmonic option

4 Waveform Display WT300E

Connectivity of Modbus/TCP*1 with YOKOGAWA’s recorders and Ethernet*1 with PLC

Digital data measured by the WT series can be acquired by YOKOGAWA’s recorder GP10*2, *3 and GM*2, *3 via Ethernet or Modbus/TCP directly. It is also possible to make use of the GA10*2 data logging software to monitor and record data.

The WT300E series can also be connected with YOKOGAWA’s PLC, FA-M3V*2 using Modbus TCP protocol for production fields.

*1 /C7 Ethernet option is required.
*2 GP10/GM/GA10/FA-M3V are manufactured by Yokogawa Electric Corporation.
*3 /E2 and /MC options are required.

5 Modbu WT300E 1

D/A output for measurement recording

The D/A option is used to output Voltage, Current, Power, and other measured data for recording to data loggers using the +/-5Vdc scaled outputs. 

6 D A Output Measurement Recording WT300E 1

Comparator Mode

This mode will compare measured, computed, and integrated values with previously set determined values by the communication command, and output (from -5V to +5V) determined results by D/A output. 

Automatic Zero Adjustment

The WT300E series compensates for any drift in the zero level by automatically performing a zero adjustment when the input ranges are changed. This is achieved in less than 100 ms and does not require disconnecting wires.


The WT300E series power meters are easy to use, cost effective, and accurate for a wide range of applications, such as production, testing, evaluation, and research and development.

For home appliances and office equipment

Production line or QA testing of electric devices

  • Compact half rack mount size helps engineers build smaller test systems with a better return on investment
  • D/A output and Modbus/TCP* functions 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.

8 Production Line WT300E 1

Development and evaluation tool for home appliances

  • 5mA range allows for small current measurements (WT310E)
  • Auto ranging function during integration mode
  • Range skip (range configuration) function provides the ability to select usable ranges in advance. Auto ranging enables the WT300E series to rapidly adapt to changing input conditions.

The range skip function reduces the transition period between range changes. The WT310E can measure both large and small currents accurately in a single test. This can reduce the total evaluation period or remove the need to use two, rather than one, power meters for the application, thereby saving on capital cost of testing.

3 Input Signal Change

Testing to international standards, such as IEC62301, Energy Star and SPECpower*1

  • The WT310E has a high measurement resolution of maximum 100 μW under the 5 mA range setting.
  • Simultaneous measurement of normal power parameters, harmonic components and THD.
  • Dynamic input capability of crest factor maximum 300 (Peak value/minimum effective RMS value)
  • Free PCM software for IEC62301*2 testing

The WT310E together with the Power Consumption Measurement (PCM) software enables users to perform standby power testing in accordance with international standards.
*1 Coming soon
*2 The IEC62301E2.0 is a reference standard in the EN50564: 2011 Directive. This software corresponds to a test method of those two standards.

9 International Standard WT300E 1

Evaluation of large current equipment

  • Direct high current measurements of up to 40Arms without using external sensors (WT310EH)
  • 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.

10 IH Cooking Heater WT300E 1

 For industrial equipment and transportation

Automotive- Battery or DC driven device evaluation

  • Accurate DC measurements: 0.3% total
  • Direct high current measurement of up to 40A without any external current sensor.
  • Charge/Discharge energy measurements for batteries

11 Automotive WT300E 1

Duration testing and efficiency measurement for industrial motors and rotating machinery

The WT300E series provides reliable current integration (Ah) and Energy (Wh) measurements for up to 10,000 hours. The D/A option can be used to transmit these measurements to an external data logger or recorder, such as a ScopeCorder, and monitor and log data along with other parameters, such as temperatures, torque, and rotation speed. The Modbus/TCP communication with /C7 option is used to save and monitor the measurement results of up 200 chs. YOKOGAWA GA10 data logging software can be used directly to save data along with other parameters such as temperatures, torque and rotation speed by this Modbus/TCP Protocol.

  • Integration measurements over long periods of time
  • Modbus/TCP Protocol for data recording
  • DC, 0.1 Hz to 100 kHz broad bandwidth capability 

13 Durantion Testing WT300E 1
Conformance and evaluation testing of uninterruptable power supplies (UPS)

  • Maximum harmonic order settings 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, efficiency, frequency and THD. The average active power data also provides accurate values of power consumption. This equipment along with the WTViewerFreePlus software helps to simultaneously measure all necessary parameters required to test a UPS, thereby reducing the evaluation time.
14 Confomrance WT300E 1

Life Cycle Assessment



B9284LK External Sensor Cable

B9284LK External Sensor Cable

For connection the external input of the WT3000 to the current sensor.
Length: 50cm
Connection Cable 705926

Connection Cable 705926

Applicable for DL850 and WT300 series.
Conversion Adapter 758924

Conversion Adapter 758924

For conversion between BNC and female banana plug
Applicable for DL750/DL750P, SL1000 & SL1400.
Fork terminal adapter 758921

Fork terminal adapter 758921

Adapters for fitting a 4mm banana plug to a fork terminal. Set contains one black and one red clip. 1000 Vrms-CAT II.
Large Alligator-clip Adapter 758929

Large Alligator-clip Adapter 758929

Rated at 1000V. Attaches to the 758917 test leads. Sold in pairs.
Applicable for DL750/DL750P, SL1000, SL1400.
Measurement lead set 758917

Measurement lead set 758917

A set of 0.8m long red and black test leads, used in combination with a pair of optional 758922 or 758929 alligator-clip adapters. Appliable for DL750/DL750P & SL1400.
Safety Terminal Adapter Set 758923

Safety Terminal Adapter Set 758923

Two adapters in a set (spring-hold type).
Safety Terminal Adapter Set 758931

Safety Terminal Adapter Set 758931

Screw-fastened adapters. Two adapters in a set. 1.5 mm Allen Wrench.
Safety mini clip (hook type) 701959

Safety mini clip (hook type) 701959

Set contains one black and one red clip. 1000 Vrms-CAT II.
Small Alligator-clip Adapter 758922

Small Alligator-clip Adapter 758922

Rated at 300 V. Attaches to the 758917 test leads. Sold in pairs.
Applicable for DL750/DL750P, SL1000, SL1400
BNC Aufsteckshunts