Could we use CycleRmsAverage to calculate some scalar values

[Khammonh]

Hi there

Any one could confirm that , could we use CycleRmsAverage on measurements class (On Enterprise library) to calculate  

VoltageCycleAverage, VoltageCycleRms. As by definition we should need period and dt which is a timing related value. But this method take array of double as an input data instead of AnalogWaveForm instant's class which would includes both Vertical axis data (array of Double) and horizontal axis ( array of DateTime or PrecisionDataTime structure). Hence , how this method could get the timing information to determine Period and dt . The array of double wouldn't tell any thing about horizontal space . If the sampling rate is unknown how  could we know how far the 2 adjacent points are located a part thus dt is unknown . With the same logic Period is also unknown. Thus I have a big question , how robust this method is to calculate the above mentioned values.

Please tell me if any one know.

Regards

[Dustin_D]

Hi Khammonh,

You'll notice that one of the arguments of the CycleRMSAverage function is waveform size.  Since this function is for only one period time does not factor in as long as the size of the waveform is known.

I hope this helps out!

Regards,

[Khammonh]

Hi Dustin

Thank for reply but I didn't see the overload of CycleRmsAverage that take waveform as argument , there are only two overload versions and both take an array .

Anyway I create a function to find Period base on waveform data which could be shown bellow in VB.Net and it is easy to convert it into C# :

Private Function GetPeriod(ByVal Data As AnalogWaveform(Of Double), ByVal Mid As Double) As Double

Dim Ret As Double

 Dim DateData() As PrecisionDateTime = Data.GetPrecisionTimeStamps

Dim V() As Double = Data.GetRawData

If V.Count = 0 Then Return 0

Dim I As Integer

Dim IsRising As Boolean = False

Dim IsCross As Boolean = False

 Dim Cross As Short = 0

Dim T1, T3 As PrecisionDateTime

Dim Delta1, Delta2, Delta3 As Double

 For I = 0 To V.Count - 1

Delta1 = V(I + 1) - V(I) 'for Edge detection

Delta2 = Mid - V(I) 'for crossing detection

Delta3 = Mid - V(I + 1) ' for crossing detection

IsRising = IIf(Delta1 > 0, True, False) 'Positive Delta1 when is rising edge and negative when falling

If IsRising Then

IsCross = IIf(Delta2 > 0 And Delta3 < 0, True, False)

Cross += 1

Else

IsCross = IIf(Delta2 < 0 And Delta3 > 0, True, False)

Cross += 1

End If

If IsCross Then

If Cross = 1 Then ' find 1st cross time

T1 = DateData(I) + (DateData(I + 1) - DateData(I)) / 2

End If

If Cross = 3 Then 'find 3rd cross time

T3 = DateData(I) + (DateData(I + 1) - DateData(I)) / 2

End If

End If

Next

Ret = T3.Subtract(T1).TotalSeconds

Return Ret

End Function

So when we get period we can calculate VoltageCycleAverage and VoltageCycleRMS by the formula giving in the definition.

Regards

[Dustin_D]

Khammonh,

CycleRMSAverage does not take a waveform as an argument, it takes a double array, but it also takes the size of that double array.  That's all that is needed to calculate VoltageCycleRMS and VoltageCycleAverage for a single cycle of the periodic signal.

Regards,