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Entry type: FAQ Entry ID: 82454925, Entry date: 12/02/2013
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7KM42 - Setting Reactive Power Measuring Type by powerconfig

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QUESTION:

What is the difference between Qn, Q1 und Qtot which can be set as “Reactive Power Measuring Type” in a PAC4200 by Powerconfig?

ANSWER:

If all existing power values over the fundamental of voltage (= U1; Sinusoidal with mains frequency) are shown graphical, it results in a general tetrahedron:



See also the following FAQ:
http://support.automation.siemens.com/WW/view/en/51542936

The adjustable options on Powerconfig Q1 and Qtot meet the reactive power identifiers shown in the tetrahedron:

Q1        =          Displacement reactive power over the fundamental U1
Qtot       =          Total reactive power

It is not possible toshow Qn in the graphic above and is explained as follows:

Qn = Shift reactive power over fundamental U1 + harmonics U. Because of, in practice, most commonly high fundamental frequency content of the voltage results: Qn ≈ Q1

Q1 is usually to use as a preferred setting, particularly as their compensation systems to obtain cos φ, which is directly related to this.

Note for the devices PAC3100 and PAC3200:
Output for reactive power is always Qn.

Mathematical context:

 

FAQ_PAC4200_QX_EN.PDF (92 KB) ( 92 KB )  

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