The common access to imaging methods based on ionizing radiation requires also radiation protection. The knowledge of ionizing radiation exposure risks among the medical staff is essential for planning diagnostic procedures and therapy. Evaluation of the knowledge of radiation safety during diagnostic procedures among the medical staff. The study consisted of a questionnaire survey. The questionnaire consisted of seven closed-ended questions concerning the knowledge of the effects of exposure to ionizing radiation as well as questions related to responder's profession and work experience. The study group included a total of 150 individuals from four professional groups: nurses, doctors, medical technicians, support staff. The study was carried out in the three largest hospitals in Gdańsk between July and October 2013. The highest rates of correct answers to questions related to the issue of radiation protection were provided by the staff of radiology facilities and emergency departments with 1-5 years of professional experience. The most vulnerable group in terms of the knowledge of these issues consisted of individuals working at surgical wards with 11-15 years of professional experience. Education in the field of radiological protection should be a subject of periodic training of medical personnel regardless of position and length of service.

In a power system, the voltage waveform usually contains harmonics and sometimes interharmonics, often defined as components of frequency greater than the fundamental voltage component but not of its integer multiple. Previous studies have reported a minor effect of voltage interharmonics on a cage induction machine. This paper reveals their extraordinary harmfulness for induction motors. Namely, voltage interharmonics may cause high vibration, which can result in machine damage. In addition, interharmonics can lead to torque pulsations corresponding to the natural frequency of the first elastic mode. Consequently, possible torsional resonance may cause destruction of a power train. In this study, the results of investigations on undesirable phenomena due to interharmonics are presented for seven motors with a rated power 3 kW–5.6 MW.

Sinusoidal voltage fluctuations can be considered a specific result of the occurrence of voltage subharmonics and interharmonics, which are components of low frequency or not being an integer multiple of the frequency of the fundamental voltage harmonic. These components—symmetrical subharmonics and interharmonics—are of the same magnitude, while their frequencies are symmetrical with respect to the fundamental frequency. Depending on their phase angles, various kinds of voltage fluctuations can be distinguished: amplitude modulation, phase modulation and intermediate modulation. In this study, the effect of phase angles on noxious phenomena in induction motors was analyzed. Additionally, torque pulsations and vibrations of an induction motor under sinusoidal voltage fluctuation and a single voltage subharmonic or interharmonic were compared. The investigations were performed with the finite element method and an experimental method. Among other findings, it was found that for some phase angles torque pulsations could be about ten times higher than for other angles, roughly corresponding to the amplitude modulation.

A particularly promising industrial prime mover is a line start permanent magnet synchronous motor (LSPMSM). LSPMSMs, just as other energy receivers, are exposed to the noxious impact of various power quality disturbances. Previous works on this issue have been limited to the effect of voltage harmonics, voltage unbalance and voltage deviation on the motor. This study initiates novel research on the LSPMSM supplied with the voltage containing subharmonics, which involve components with frequencies less than that of the fundamental component. The results of experimental investigations are presented for a factory-made 3-kW LSPMSM. Voltage subharmonics were found to exert an extraordinarily harmful influence on motor under consideration. Subharmonics of values similar to those reported in real power systems were determined to cause unacceptable vibration.

Periodic voltage fluctuations are considered superposition of the fundamental harmonic and additional components, namely subharmonics and interharmonics (SaIs) —components of frequencies that are less than or not integer multiples of the fundamental frequency. Therefore, voltage fluctuations (VFs) occurring in real power systems are practical examples of various voltage SaIs. VFs and SaIs interconnected with them exert a harmful effect on rotating machinery, transformers, control systems, and electronic appliances. This study analyzes induction motors under VFs using experimental and finite element methods. The vibration and torque pulsations are compared for a single voltage subharmonic/interharmonic injection and VFs with various shapes of the modulating function. The results show that requirements concerning flicker severity, as well as the proposals to limit SaIs included in the standard IEEE-519:2022, do not protect induction motors against excessive vibration. Recommendations concerning the limitations of SaIs are formulated.

In power systems, various power quality disturbances are present, including voltage deviation, voltage unbalance, and voltage waveform distortions. Voltage waveform distortions are usually identified with harmonics, but in some systems, subharmonics (subsynchronous interharmonics) and interharmonics may also occur—that is, components of frequency less than the fundamental frequency, or not an integer multiple of it. This study examines torque pulsations of an induction motor under voltage subharmonics combined with voltage unbalance. The motor and the driven DC generator vibrations were analysed under the power quality disturbances. Investigations were carried out using finite element and empirical methods. Experimental tests were performed for the maximal levels of the power quality disturbances specified or proposed in the relevant standards. For the investigated motor, under voltage subharmonics or voltage unbalance occurring as a single power quality disturbance, the vibration level was within the prescribed limit. However, under unbalance combined with subharmonics, the level could be accepted for only a limited time. Consequently, the permissible level of voltage subharmonics in non-generation installations should be interconnected with the voltage unbalance in the power system.