The power spectral density of audible noise and electric disturbances in ship’s electrical drive systems with frequency converters

The presented dataset is part of research focusing on the impact of the ship's electrical drive systems with frequency converters on vibrations and the level of audible noise on ships. The correlation between the power spectral density of the audible noise level and electric disturbances in the supply line of the motor was examined. The measurements using a model of the marine drive system with a frequency converter were performed at laboratories of the Department of Ship Automatic Control at Gdynia Maritime University. The 5.5 kW squirrel cage asynchronous motor was connected directly to the output of the frequency converter or through an additional passive LC filter and coupled with the DC generator, which was loaded by an adjustable resistor. The tests took place with the motor voltage frequency set up at 46 Hz and different switching frequencies of an inverter (12 kHz and 6 kHz), for the nominally loaded motor. The sound level meter was pointed directly to the source, positioned at a distance of 1m from the motor lifting eye, in the motor axis of symmetry, from the drive end, 1m above the floor. The data acquisition of audible noise level (A-weighted), AC motor voltage and current waveforms were carried out with the digital measurement system (shown in Figure). The sampling frequency was equal to 20 kHz. A power spectral density analysis of all recorded waveforms was carried out in off-line mode, in the LabVIEW environment. The power spectral density was calculated with the use of a Fourier transformation, where the procedure of the spectrum estimator averaging was made at time intervals (section averaging). The resolution of spectral analysis was equal to 5 Hz. The digital system for measurement and analysis of audible noise and disturbances in the motor supply line, the hardware part (on the left), the software part (on the right).