This trivialization can, in some conditions, cause certain problems in the equipment. Today, with the "pressure" to reduce energy costs, is quite often we find driven motors with frequency inverters. We are quite often we are asked about the causes that are behind some atypical behavior of rotating machines. But not only: other abnormalities / damage not only the imbalance, can give increased amplitude 1xRPM, as surely we will be able to address in future issues of this Newsletter.Ĭase study 3 – Analysis resonance vibrations in an electric motor The inspection carried out concluded that the cause of the high levels in the presence vibrométricos the machine was associated with a resonance condition, caused by the proximity of the natural frequency of the system and the motor operating frequency (1xRPM).Īs found in this case, MRI is one of the causes that may lead to high amplitudes 1xRPM. This condition is illustrated in the frequency spectrum shown in Figure 5.įigure 9 – Analysis resonance vibrations – Bode diagram taken in the horizontal directionĬase study 2 – -Conclusão resonance vibrations Analysis The spectral analysis performed showed that vibration levels are present in the engine, about everything, influenced by the operating frequency range (1xRPM motor=16,65 Hz). In support of the engine, side pulley, The data presented above show a significant difference between the amplitudes vibrométricas recorded in two radial measuring directions (Vertical and horizontal). data collected and presented in Table I., It reveals that the recorded levels are vibrométricos, mostly, considered "Severe" according to the evaluation criteria adopted. Only the engine support, side pulley, according to the measurement and directions Vertical Axial, vibrométricos the levels are considered good / acceptable. The vibration analysis results in electric motors, shown in Table I, It reveals that the recorded levels are vibrométricos, mostly, considered "Severe" according to the evaluation criteria adopted. this feature, illustrated in Figure 1, It is caused by an eccentricity static condition in the air gap.įigure 4 – Scheme equipment with the location of the measuring points The filtered amplitude had a value 6,7 mm/s RMS. The results of vibration analysis in electric motors observed that predominated in the spectrum the second harmonic frequency of the electrical network (100 Hz). Case 1 Example test performed on an engineĪn engine running at 2964 presented rpm vibrations above the established limits for this type of equipment. That way, intended to eliminate excess vibration that this problem may generate, increasing life two components, preventing unscheduled stops due to premature deterioration or even breakage of some of the engine components or coupling union. This essay, accomplished, common vibration analyzer and the engine is running under normal operating conditions, It aims to identify the existence of leg-thigh conditions that often are the source of the static eccentricity between iron AC induction motors. Case 1 – Paw Assay for thigh-identification conditions as a cause of eccentricity situations in Static Induction Motors AC This latter approach, due to economic and inserted also needs in modern maintenance philosophies, also results from the fact that maintenance managers of facilities where this approach is practiced, feel comfortable with the most common condition monitoring techniques. But also are already common facilities where preventive maintenance is performed only based on knowledge of the machine's working condition. As the MTBF of this type of machine eight years in the petrochemical industry ( for a working 8760 hours / per year) it is common to use very-intervals shorter. This means that today is often the use of preventive maintenance based on time approach as the maintenance of these machines. The three-phase induction electric motor is the most common drive and an unexpected malfunction in such machines can be very onerous economic implications. Several case studies here are presented in Vibration Analysis in electric motors.