Reactive Power [VAR] and Reactive Energy [VARh]

Reactive power [VAR] and energy [VARh] can be obtained by calculation.

But first, it is important to understand how parameters are calculated at different time intervals.
It is particularly important to understand the principle of calculation for parameter [Power] when it becomes from electrical power into electrical energy.

smart-MAC parameters, symbol
Real-Time and Minute interval
Hour, Daily, Weekly, Monthly intervals
Voltage, V
Voltage [V]
Arithmetic average of Voltage [V]
Current, ACurrent [A]
Arithmetic average of Current [A]
Power, WInstant Power [W]
Energy for the period [Wh]
Power Factor, PF
Power Factor (cosФ)
Arithmetic average of Power Factor
Energy, WhCumulative energy meter [Wh]
Cumulative energy meter [Wh]

Energy meter smart-MAC measures:

-Active Power [Power]

-Power Factor (cosF) [PF]

That's enough to get the calculated Apparent Power and Reactive Power. Remember physics course:)

Active Power = Apparent Power * cosФ

from here:

Apparent Power = Active Power / cosФ
*) it is important in our case to divide the Active Power on the Power Factor (cosФ).
Reactive Power = Apparent Power * sinФ
where angle Ф = arcos (cosФ)
To display the reactive power and energy in digital or charts Widget:

- open the Widgets settings;
- in section "Arithmetic operation" select the function f(x);
- click on the "Edit" to open the window for editing complex functions.
On the left side you can see a list of the data and their symbol for use in the formula. When you build formulas, you can use any arithmetic and mathematical functions of the JavaScript language. To test the function, use the button "Check" and test the values of variables.

The formula for the calculation of the Reactive Power for the first phase of three-phase energy meter will look like:

(d.W1 / d.PF1) * Math.sin(Math.acos( d.PF1 )) ||0
*) the operator "|| 0" returns Zero if Power Factor is zero, for example, if one line is disabled

The formula for the calculation of the Total Reactive Power in kVAR of three-phase energy meter will look like:

((d.W1/d.PF1)*Math.sin( Math.acos(d.PF1) )||0 + (d.W2/d.PF2)*Math.sin( Math.acos(d.PF2) )||0 + (d.W3/d.PF3)*Math.sin( Math.acos(d.PF3) )||0)/-1000   
*) to multiplication by a negative will build the chart in the down axles


Note:

- for a minute and Real-Time intervals,  it will be Reactive Power [VAR]

- for hour, day and above intervals, it will be Reactive Energy [VARh]

- computations are averaged for the period because the calculation used average Power Factor for the period (cosФ)

Enjoy your measurements!

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