They have been the instrument of choice for a wide range of applications in production testing, quality assurance and Research & Development.

This new family consists of the Models WT310E single phase, WT310EH single phase high current, WT332E two-element and WT333E three-element versions. These new units offer enhanced measurement accuracy of 0.1% of reading +0.05% of range. The WT310E provides extremely low current measurement capability to 50 micro-Amps, and up to 26 Amps RMS. For the engineer doing Stand-by-Power measurements, Energy Star®, SPECpower and IEC62301 / EN50564 testing, Battery Charger and other low level power measurements, the WT310E is the ideal solution.

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.