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Power Group and Power Phase – What’s the Difference?

What is three-phase power?

Three-phase power systems are the common method for the generation, transmission and distribution of power. Although there is a clear trend for poly-phase (>3) engines, the three-phase engine is still the most used engine.
In this blog post we are first going to describe the basics of a three-phase engine. Then we will tell you what a DEWETRON Power Analyzer contributes to power measurement and power analysis.

For the generation of three-phase power, three chokes are located apart from each other in an angle of 120°. Depending on the position of the poles within the magnetic field, the electrons move in different directions in at least two chokes. Electrons are moving back and forth in all three lines. This not always happens in accordance with the direction and speed of the other two lines. For every cycle, there are three positive and three negative peaks.  This is because only one of the three lines can reach its peak current at one time.

Power groups and power phases

When DEWETRON talks about Power Analysis, we don’t only mean the analysis of voltage and current magnitude, active power and reactive power. We mean additionally the analysis of harmonic, flicker and voltage fluctuation as well as the mechanical power analysis. This is important to get a complete picture from your device under test.


For power analysis, it is essential to differentiate between power phases and power groups. What we call Power Group is a wiring type or connection schematic of one or several power phases (i.e. three-phase Line-Line connection) within the power analysis option in our measurement software OXYGEN. Power phases are voltage-current pairs building a power system like a generator or motor.
Analyzing a power group, each power phase is evaluated individually and synchronously and the power group is evaluated in total as well. Each power group shares a common fundamental frequency.


DEWETRON Power Analysis

The Power Analysis option in OXYGEN provides the analysis of 1-9 phase power systems. The user can select from different predefined wiring schematics, i.e. 1P2W, 2V2A, 3P3W, 3P4W or 2 x 3P3W. Different power phases can be logically summarized to so called power groups (= power systems).
Also, the Power Analysis option provides basic features like voltage, current RMS, AVG, fundamental and symmetrical components, active/reactive/apparent power (total and fundamental) and energy. The analysis of harmonics (IEC 61000-4-7), flicker (IEC 61000-4-15), flicker emission (IEC 6140-21) and mechanical power/efficiency can be proceeded within the advanced features. If the grid compatibility of renewable energy generators like wind turbines shall be evaluated, the expert option is the right add-on.

The Power Analysis option of our data acquisition software OXYGEN is the core feature of our PA-series devices. But it also turns any other DEWETRON measurement device into a fully featured Power Analyzer. Of course, our measurement software comes along with many more useful features and tools. Curious?
Get to know all our OXYGEN software features! Or get to know useful software usage tips in our DEWETRON Academy!
AND: We just released the latest version of our software – OXYGEN 5.2! Generating an efficiency map live during the measurement is just one of the new features!

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