Spectrum Analysis for Condition Monitoring and Fault Diagnosis of Ventilation Motor: A Case Study

Abstract

In modern power systems, since most loads are inductive by nature, there is an ongoing power quality issue and researchers’ interest in improving the power factor is widespread, as inductive loads have a low power factor that depletes the system’s capacity and has an adverse effect on the voltage level. The measurement and acute analysis of voltage- and current-level waveforms is essential to tackle power quality issues. This article presents a detailed case study and analysis of real-time data measured from a frequency converter, which is used to operate the motor of a ventilation system. The output of the frequency converter is a highly distorted current wave. A hybrid Fourier transform (FT)- and wavelet transform-based solution has been proposed here to diagnose and identify the causes of motor failure in the ventilation system. The traditional FT did not give a detailed analysis of this type of signal, which is highly contaminated by noise. Therefore, first, the signal is preprocessed for data denoising using the wavelet transform. Second, the Fourier analysis is performed on the filtered signal for frequency analysis and segregation of fundamental frequency components, higher-order harmonics, and suppressed noise. The spectrum analysis reveals that the noise is generated due to the rapidly switching circuits in the frequency converter and this unfiltered signal at the output of the frequency converter causes motor failure.

Novel Approaches to Electrical Machine Fault Diagnosis

“…Power quality issues related to electrical machine diagnostics are analyzed in [8]. In modern power systems, the low power factor of inductive loads poses a significant power quality issue, impacting the system's capacity and voltage level.…”

Evaluation of three consumers' contribution to the current and voltage distortions at the point of common coupling

“…The negative consequences of the power supply system (PSS) voltage and current distortions are known and widely reported [20]- [22]. Non-sinusoidal current consumed by semiconductor elements [23] leads to a decrease in  ISSN: 2302-9285 the quality of electrical energy [24], [25]. At the same time, quality indicators are regulated by international standards (IEEE 1159-2019, IEEE 519-2014), which establish the permissible level of both voltage (THDu) and current distortions (THDi).…”