1-4
IM WT310E-01EN
What Is a Measurement Function?
Measurement Function
The physical values—such as rms voltage, average current, power, and phase difference—that this
instrument measures and displays are called measurement functions. Each measurement function
is displayed using a symbol that corresponds to its physical value. For example, “U” corresponds to
the voltage. The unit is “V.” When the measurement mode is RMS (see section 1.2, “Measurement
Conditions”), the true rms voltage is displayed.
WT310E and WT310EH
Input Element
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 WT310E/WT310EH has one input element.
Input element
Voltage input
Current input
Wiring System
The WT310E/WT310EH uses a single-phase, two-wire system.
Wiring Units and
Σ Functions
The WT310E/WT310EH does not have multiple input elements that can be combined into wiring
units and Σ functions.
WT332E/WT333E
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 WT333E 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 WT332E/WT333E, 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.
Three-phase, four-wire
Σ
Input elements
Wiring system
Symbol indicating the wiring unit.
Voltage input
Current input
1
2
3
1.1 Items That This Instrument Can Measure
