Frequency Period 3Ph

The Frequency Period module calculates the base frequency of the input signal. To do this, the signal is first filtered with a Butterworth low-pass filter. The zero crossings of the input signal are then determined from the filtered values, and the frequency is calculated from their difference. The results refer to one or more periods, depending on the configuration. The statistical results refer to the entire runtime or the time at which the statistical results were last reset.

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.

• Buffer Length: Length of the input buffer.

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

• Min Frequency [Hz]: Minimum measurement frequency to be expected.
• Max Frequency [Hz]: Maximum measurement frequency to be expected.

• Periods: Number of periods that influence the calculation. (Period length = sample rate/frequency).

• Filter Order: Order of the low-pass filter. The stability of the filter must be considered for the setting. Only values up to the tenth order are allowed.
• Cut Off Frequency [Hz]: Cut-off frequency of the low-pass filter.
• Min Input: Minimum input value (RMS) over one period. This parameter prevents the calculation of input values that are too small.
• ROCOF Avg Window Order: Window size of the sliding average value for the calculation of the ROCOF.