Spectrum 3Ph

The Spectrum module calculates the magnitude spectra of the current and voltage values. These are suitable for analyzing the input signals in the frequency range. The size of the input buffer is half the window length.

In the Beckhoff Information System you will find the documentation of the TF3650 TwinCAT 3 Power Monitoring function with descriptions of the corresponding PLC library.

• FFT Length: Length of the FFT. It must be greater than one and an integral power of two.

• Window Length: Length of the analysis window in samples. The length must be greater than one and an even number. It must not be greater than FFT Length.

• Sample Rate [Hz]: Sample rate (samples per second) of the input signal.

• Scaling Type: Enables selection of the scaling used if absolute scaling is required. See: E_PMA_ScalingType

• Window Type: Defines the window function used. The window type HannWindow is a good default value. The windowing can be switched off by the use of the window type RectangularWindow. See: E_PMA_WindowType

• Transform To Decibel (optional): Boolean value indicating whether the result of the FFT should be transformed to the decibel scale, corresponding to the transformation x → 20 * log10(x).

• Decibel Threshold (optional): Very small floating-point value greater than zero. Values smaller than this number are replaced with this value before any transformation to the decibel scale, since the logarithm of zero is not defined mathematically. The smallest possible value is 3.75e-324.