With all condition monitoring sensors from Balluff, time domain evaluations such as RMS, peak, magnitude, kurtosis... can be evaluated.

The following illustration shows a vibration signal with 1Hz vibration frequency and an amplitude of 3.

If a spectrum (frequency signal evaluation) is formed from the time domain evaluation by the FFT, the signal looks like below.

And here lies the difference between the BCM variants. Only the BCM0003 can evaluate the spectrum.

Hir is a display error. The amplitude should also be 3.

Here again summarized in a representation:

In the last chapter, the relationship between a time signal and a subsequent frequency signal was illustrated using one signal.

However, in practice it is far more complex and the time signal already has a proportion of many signals (red signal in the illustration).

The frequencies contained in the red signal are shown with the different proportions in blue, purple and green.

There is a correlation if you look at the "frequency domain" on the right-hand side.

The amplitude of the frequencies and their individual frequencies are easy to recognize, which is somewhat difficult in the time domain. It is also easy to see how many different frequencies are contained in a signal.

An example with two frequency signals is considered. These two frequencies can also be clearly seen in the time signal (next image).
These frequencies were used for illustration and simplification.

1. Signal = 1Hz and an amplitude of 3
2. Signal = 16Hz and an amplitude of 1

The amplitudes and their heights are quite easy to recognize. The individual frequencies cannot be easily extracted from the time domain display.

If you now look at the frequency signal rather than the time signal, you can see the individual frequencies with the amplitudes of the signals very clearly.

Here again summarized in a representation:

In practice, there is usually also noise on a signal, which makes it more illegible when viewed over time.

The next image shows a signal with noise. Here you can already see the difference in the time view of a signal.

If the frequency signal is displayed and evaluated again, you can see that the noise is in the range <0.3.
The frequency to be viewed is displayed with a higher deflection (amplitude) and can therefore be evaluated more accurately.

Here again summarized in a representation:

A signal with several frequencies and additional noise can therefore not be evaluated well in a time signal.
To simplify matters, the following signals were used in this example

1. Signal = 1.5Hz and an amplitude of 3
2. Signal = 16Hz and an amplitude of 1

The next image shows how the sine wave is no longer displayed cleanly even with noise.

In the frequency domain, the proportional frequencies and amplitudes can be evaluated more easily.
The noise is almost zero. All relevant signals are displayed with the corresponding amplitude/frequency.

Here again summarized in a representation:

The following settings can be made for the spectrum analysis in the spectrum configurations.

The data points of a spectrum are constant at 1714 data points per spectrum.

When selecting the spectrum range, it depends on the spectrum resolution that you want to achieve. It also depends on the speed (see table above).

The averaging function can be used to average several spectra together in order to suppress spikes or one-off events. In the image shown below, 8 spectra are averaged.

By averaging 8 in this example, the acquisition time is increased accordingly. By averaging 8 spectra, the acquisition time of the table shown above of 286ms at 6000Hz spectrum range is multiplied by 8.

The spectrum resolution remains the same.

A distinction is made between two settings in the band mosu settings.

More on this in the next chapters.

Multipliers for the rotational speed are to be used if the rotational frequency of the axis (bearing) to be monitored changes.
The band limits are always adapted to the current rotational speed by the factor.

The calculation for this is Factor x rotational frequency = damage frequency range.

The factors can be specifications from drive manufacturers. These can be used in this parameter data.

The speed must be provided to the sensor via one of the three paths.

• Pin 2 Input via a clock signal from an external sensor
• Process data output
• Static input of the parameter data

The absolute band limits can be used if the rotation frequency is static. The upper and lower band limits can be defined in each case.