I have a dataset of vibration amplitude (g), I already developed the code to convert it to a Fast Fourier transform. The results are just like I expected (mostly the highest peak shows at 50 Hz). Note that the fs for this dataset is 1000 Hz. Link to the dataset: Article Wind turbine blades fault diagnosis based on vibration datas...

Now, I am trying to apply the same code to another datasets. But, in this case they show the highest peaks at highest frequencies (and many of them when it is supposed to show the highest peaks around 30 Hz for an engine of 1700 rpm). Note that the fs for this dataset is 12000 Hz. Link to the dataset:

https://info.endaq.com/hubfs/Plots/bearing_data.csv

Why is this happening?