WT332/WT333
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 WT333 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 WT332/WT333, 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.

The WT332/WT310 digital power meter is a high-performance power measuring instrument from Yokogawa, Japan, and belongs to the WT300/WT310 series. Here are some of its features:
High precision measurement: The basic accuracy can reach 0.1% of the reading, which can provide accurate and reliable data for various power measurements.
Wide frequency range: The frequency range of DC measurement is 0.5Hz to 100kHz, which can meet a variety of AC and DC measurement needs.
Multi-parameter measurement: Can measure all AC and DC parameters, including voltage, current, active power, reactive power, apparent power, etc., can also be conventional and harmonic measurement without changing the measurement mode.
Compact design: half frame size design, compact size, space saving, easy to install and use.
Rich interface: standard USB, GPIB (or RS232) interface, optional Ethernet interface, easy to connect with computers or other devices, to achieve data transmission and remote control.
Special measurement function: With 50μA low current measurement (WT310 only) and 40Arms high current measurement (WT310HC only), can adapt to different current range of measurement scenarios.
High-speed data update: Up to 10 readings per second can be updated quickly and accurately to reflect changes in measurement data and shorten the time of test procedures.
Included software: Included with WTViewerFreePlus software, can be used to monitor and save the measurement parameters, but also can display the value, waveform and trend chart of the measurement data, convenient for users to analyze and process the data.