This paper presents the obtained results of experimental tests and modelling of lightning disturbances that were propagated in a model of aircraft cable bundle and caused by multiple lightning return-strokes interactions. The work is a continuation of previous research, which was concerned mainly with the interaction of lightning discharge with a single return-stroke. The section of the cable harness arranged above the metal plate was investigated. In one of its wires, a multiple-stroke current representing indirect lightning effects was injected from an impulse current generator dedicated to avionics immunity tests. Overvoltages induced at the ends of other wires surrounded by a braided shield, as well as the influence of line parameters and shield grounding condition on the shape and level of observed transients, were examined. The computer simulation results match the measurement data with satisfactory accuracy, and therefore, the presented model can be used to estimate indirect lightning effects in the wiring harness of avionics.

Experimental and computer investigations were conducted into long-duration impulse current distribution in the lightning protection system, supplying network, and electrical installation of a test house that was equipped with household appliances. Long-duration impulse currents simulating lightning continuing currents were injected from the unique current generator into the test object. The current distributions in the elements of the test object were measured using current shunts, coaxial cables, and digital oscilloscopes, then they were modeled using the ATP-EMTP software package. The obtained results show a quite good agreement between the measured and computed current waveforms. The relationships between the values of currents at different points of the conductive installation are similar, as reported in previous studies on the fast-changing lightning return stroke component distribution, although the efficiency of the lightning protection system (LPS) is a few percent better for the long continuing current component in the case of a strongly conductive ground at the test site in Huta Poręby, part of the Rzeszów University of Technology. Due to the relatively low content of high-frequency components in the long continuing current spectrum, the waveshape of this lightning component is practically the same throughout the entire tested installation.

Piezoelectric actuator, as one of the components of active vibration control system, influences the effectiveness of vibration reduction. To make the reduction process most effective, the efficiency of all its components must be maximized. Hence, optimizing shape of PZT in terms of efficiency...

This paper presents the characteristics of overvoltages and surge testing of equipment, as well as discusses the means of surge protection. The analysis of surges occurring in the high-voltage laboratory of Rzeszow University of Technology causing frequent damage to the measuring equipment during operation of the Marx generator was carried out. The nature of the overvoltages was identified and methods of their reduction using varistor overvoltage limiters and transil diodes were proposed. A high-resolution digital oscilloscope and high-voltage differential probes were used for the measurements. W artykule przedstawiono charakterystykę przepięć i badań wytrzymałości udarowej urządzeń, jak również omówiono środki ochrony przeciwprzepięciowej. Przeprowadzono analizę wykonanych pomiarów przepięć występujących w laboratorium wysokich napięć Politechniki Rzeszowskiej powodujących częste uszkodzenia sprzętu pomiarowego podczas pracy generatora Marxa. Dokonano identyfikacji charakteru przepięć oraz zaproponowano metody ich ograniczenia z wykorzystaniem warystorowych ograniczników przepięć oraz diod lawinowych typu transil. Do pomiarów wykorzystano oscyloskop cyfrowy o dużej rozdzielczości oraz wysokonapięciowe sondy różnicowe.

A study of the relative permittivity and electric strength of dielectrics printed by focus deposition modeling was presented. These electrical parameters determined the life-time reliability of devices made of dielectrics. Samples of PLA, ABS, PETG and ASA were tested according to IEC specifications. The dependence of the electrical properties of the samples on the type of material and printing precision was observed. Relative permittivity tests were carried out in the acoustic frequency band from 20 Hz to 20 kHz. It allowed analysis in a higher band than has been done in other publications to date. The electric strength of materials at 1.2/50 μs surge voltage was examined, which has not been widely analyzed before. Weibull plots, as a basis for determining the risk of failure, were prepared. The PETG FR (flame retardant) had the highest electric strength value, while PLA had the lowest. The differences with respect to tests at AC voltage were demonstrated. The printing technique affects the electrical strength value and location of potential electrical break-down.

In the active vibration reduction of two-dimensional structures, piezoelectric actuators of regular shapes, e.g. rectangular, circular, are commonly used. However, the shape of the transducers can be irregular, asymmetric (a-PZT), and its geometry can be an object for optimization. The paper presents an experimental validation of the application of optimal shaped a- PZT in the active reduction of triangular plate vibrations. Optimization was based on the criterion of the maximum bending moment. This means that the center of a-PZT is located at the point where the bending moment of the plate has reached its absolute maximum. The isosceles right triangular plate with simply supported edges was chosen as the research object. The research confirms the validity of the criterion used for optimization and may be an introduction to considering the use of optimal a-PZT in the active reduction of vibrations for more complex structures.