Effect Of Electrical Aging Research Articles

Electrical aging of a piezoelectric MEMS fast steering mirror and its impact on reliability

Reliability is a critical characteristic of aerospace-grade components, particularly fast steering mirror (FSM), which is one of the key devices in Free-Space laser communication terminals. The previous long-term work of FSM exposes noteworthy reliability issues about degradation of this device. This paper first demonstrates the electrical aging effect that occurs in piezoelectric-driven micro electro mechanical system (MEMS) FSM during prolonged operation. This is a significant reliability issue as it causes the decay of mechanical angle of MEMS FSM, ultimately resulting in functional failure. In order to study the electrical aging effect, firstly, a mechanical angle monitoring system is developed for the rapid and accurate identification of electrical aging failure. Secondly, we performed failure analysis by using scanning electron microscope - focused ion beam (FIB - SEM) and conducted thermal analysis experiments to confirm heat accumulation within the MEMS FSM actuator, where the electrical aging effect takes place. Thirdly, by setting up a finite element simulations (FEM) model of the step region in the actuator, the electrical aging effect resulting from heat accumulation caused by high current density under a significant electric field at the lower step is confirmed. Finally, the critical reliability issue of electrical aging, which affects the lifetime of piezoelectric-driven MEMS FSM, is improved by adjusting the layout to eliminate large electric field intensity in local region.

Impact of electrical aging on x-ray image quality and dose rate with vertically aligned carbon nanotube based cold cathode electron beam (C-beam)

The adoption of vertically aligned carbon nanotubes (VACNTs) as electron emitters in x-ray generation has opened a new path for medical imaging technology advancement. With their outstanding electron emission capabilities, VACNTs provide a distinct advantage in miniaturizing and improving the performance of x-ray devices. This research focuses on the effect of electrical aging on x-ray imaging quality and the dose rate while using VACNTs as the electron source. The study includes a thorough examination of the electrical aging effects on VACNT-based x-ray systems, with an emphasis on changes in emission characteristics, beam stability, and the resulting variations in x-ray output. Experiment results show that electrical aging has a considerable impact on the performance of VACNT-based x-ray sources, with visible changes in electron emission parameters and subsequent consequences on x-ray imaging quality. Furthermore, the study investigates the relationship between electrical aging and the x-ray dose rate, providing vital insights into radiation exposure optimization in medical diagnostics.

Analysis of Electrical Aging Effects on AC High Frequency Motor Based on Exchange Market Algorithm Model Parameter Identification

Analysis of Electrical Aging Effects on AC High Frequency Motor Based on Exchange Market Algorithm Model Parameter Identification

Electrical Aging Effect on PD Characteristics of Cellulose Pressboard Modified by Nano-TiO2

Cellulose pressboard has been widely used as internal insulation in oil-immersed transformers. Partial discharge (PD) is the main cause of the degradation of the insulation properties for electrical equipment. Nano-modification is one of the methods to improve the electrical properties of the oil–paper insulation. In this article, the effects of the oil-immersed pressboards modified by nano-TiO2 particles on PD characteristics were studied. The pressboards modified by different mass fractions of nano-TiO2 (10-nm particle size) were prepared. The electrical aging experiment was carried out on the oil-immersed pressboard. Experimental platforms for partial discharge inception voltage (PDIV) and relative permittivity were established to measure the dielectric performance of the pressboard. Phase-resolved partial discharge (PRPD) spectrograms and PD current pulses of the samples under different electrical aging states were obtained for different PD time. The surface morphology of the pressboards was observed by scanning electron microscope (SEM) to verify the effects of nano-TiO2 particles. The results showed that the values of electric field strength for the samples were 4.58 and 3.6 kV/mm, respectively, when the PD occurred in the samples modified by nano-TiO2 with 3 wt% and the unmodified ones. Compared with the unmodified pressboard, the modified one had a lower value of relative permittivity. The pulse current of the pressboard modified by 3 wt% nano-TiO2 particles under different electrical aging states was smaller than that of the other samples. The addition of 3 wt% nanoparticles was the optimum ratio to suppress the PD of the samples in the ac electrical field.

Effects of electrical aging on the structural and physicochemical properties of crosslinked polyethylene (XLPE) cable insulation material

The aim of this work is to highlight the evolution of physico-chemical properties of peroxide crosslinked polyethylene (XLPE) insulation material exposed to electrical aging. Specific analysis and characterization studies were carried out to determine the effect of electrical aging on different samples at micro and macro levels. Based on the analytical investigations, it was shown that electrical aging yielded significant changes in the chemical and thermal characteristics of XLPE. It was also showed that property loss increased with the aging time.

Effect of Electrical Aging On PPLP Insulation Characteristics in LN2

The high-temperature superconductivity (HTS) DC cable has brought huge economic benefits and has been widely used in the system with its low line loss. The Polypropylene laminated paper (PPLP) tape is wrapped around the core due to its excellent insulation properties, which produces butt gaps. Since cables in HTS DC transmission system often withstand DC and AC composite voltage, these gaps make partial discharge (PD) easier to occur. Meanwhile, degradation occurs in PPLP under long-term electrical stress, which could threaten the safe operation of the power system. Therefore, this article conducted an electrical aging test in liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) to simulate the actual operating environment of PPLP, and also measured the conductivity, relative permittivity, PD, and breakdown strength of PPLP with different aging times in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The results show that the conductivity basically increases with the increase of aging time and relative permittivity has a significant increase at the end of the aging stage. As the aging time increases, the PD activity of PPLP becomes more intense and the DC breakdown strength shows a downward trend. The reason for the deterioration of PPLP insulation performance after aging was analyzed. Besides, the effect of different alternating components on PD was studied in the case of constant effective voltage. When the alternating component decreases, the number of PD is significantly reduced.

Electrical Aging Effect on Breakdown and Charge Trap Characteristics of Polyimide Films With Different Thickness in LN2

The Polyimide (PI) film, as an excellent insulating material, is broadly utilized in superconductivity power equipment, especially under low temperature. There is an enormous influence on the breakdown performance of polymers because of the presence of surface and space charge. In order to investigate the electrical aging impact on breakdown and trap characteristics of PI films with 0.1 mm and 0.125 mm thickness, the samples suffer from diverse degrees of electrical aging in liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). The insulation strength test has been carried out on the PI film samples under different electrical aging stages in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The isothermal surface potential decay (ISPD) method is performed on the PI films to explore the behaviors of trapped charges, and the trap characteristics of the PI films are obtained. Those results indicate that the breakdown strength of the thinner PI film (0.1 mm) in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is higher than that of the thicker one (0.125 mm), and the breakdown field strength reduces with the electrical aging time increasing. The ISPD measurement results indicate that the average decay rate of surface potential in the 0.125 mm PI is faster than the other thickness during the whole decay process.

Analysis and Detection of Electrical Aging Effects on High-Speed Motor Insulation

The use of fast wide-bandgap devices in high-speed electrical drives with steep pulsewidth modulation voltage waveforms is the main cause of increased stress on the electric machine insulation system and consequently, of reduced reliability of the whole system. This represents a major concern in safety-critical applications, such as in the aerospace and electric transportation fields. The novel contribution of this work is to assess the effects of electrical aging on complex insulation systems (i.e., a whole stator winding) by analyzing easily measurable macroscopic quantities. To this purpose, an electrical aging procedure is defined, and the effects produced on three tested motors are presented. Three different analysis methods are adopted with the aim of assessing the damage caused to an ac motor winding by such steep voltage waveforms and hence to evaluate the state of aging of the insulation system.

Understanding the Impact of Corona Aging of Ester Oil Adopting Fluorescent Technique

Performance and life of any transformer depend entirely on the dielectric property of the insulation used. In recent times, ester oil is replacing the mineral oil. In this paper, effects of electrical aging on ester oil in the presence of pressboard as a barrier between high voltage and ground electrode is studied. Corona inception voltage has been used to understand the variation in the electrical characteristics of the oil with time. Corona aging induces degradation of ester oil resulting in the formation of carbonaceous particles. This leads an increase in oil concentration occurring due to particles suspension of different size. To analyze this variation, dynamic light scattering analysis is carried out with the oil samples. It was observed that ester oil is fluorescent in nature and formation of carbonaceous particles on aging leads to change in its fluorescence characteristics. To monitor and characterize the degradation, a fluorescence-based analysis is used to obtain the fluorescence data as 3D excitation emission matrix.

Effects of Continuous Operating Voltage Stress and AC Energy Injection on Current Sharing Among Parallel-Connected Metal–Oxide Resistor Columns in Arrester Banks

The capacitors of series compensation (SC) installations have to be protected against overvoltages by surge arresters. Since very high amounts of energy must be handled under fault conditions, many parallel metal-oxide (MO) resistor columns are typically arranged in arrester banks, which are also designated as metal-oxide varistors (MOVs). It is known that in rare cases, single MO resistor columns fail in consequence of excessive energy injection. It is so far an unsolved question as to whether it is allowed to replace such arresters by new ones because of possible electrical aging effects of the remaining, healthy arresters. The presented investigations indicate that the aging affects do have an impact on the residual voltage of the investigated MO resistors, but with only negligible impact on current sharing among individual columns (e.g., of a bank). Therefore, the replacement of single arresters seems to be possible at least for the investigated type of MO resistors.

Effect of Electrical Aging on the Trap Parameter of HVAC XLPE Cable Insulation

The effect of electrical aging on the trap parameter of HVAC XLPE cable insulation was investigated in this work. Thermally Stimulated Current (TSC) was used to measure depolarization current. The variation of trap parameter was calculated by means of start-up method based on the Gaussian fitting curve of TSC data. It was found that, the activation energy and the amount of trap charge obtained from TSC peak at 243K and 348K were increased after electrical aging, which may be benefit to characterize the degree of aging. The amount of trap charge in the two peaks increases as the increase of oxide dipole after electrical aging. And charge trapped described by the TSC peak at melting temperature increased after aging. It is considered that the increase of charge in the TSC peak can be attributed to the release of trap charge in the melt crystallization process, which corresponds to the α relaxation process in XLPE insulation.

The Research on the Effects of Electrical Aging on Trap Distribution in Polyethylene Doped with Nanoparticies

The photo-stimulated discharge (PSD) technology was used to characterize the trap distribution of polyethylene (PE) and the PE that doped with 5% MgO before and after electrical aging. For the PE with the aging time increasing, the internal shallow trap of the material gradually reduced and deep trap gradually increased. But for the PE that doped with 5% MgO with the aging time increasing, shallow trap gradually increased and the deep trap gradually reduced. Results show that: during the electrical aging process the PE produces a large amount of free radicals which can introduce deep traps. Adding impurity of MgO can effectively restrain charge moving that injected from electrode, thus to improve the internal electric field distortion of PE.

Electrical aging effect of ZnS based quantum dots for white light-emitting diodes

The present work reports cadmium-free colloidal ZnS:Al quantum dot (QD) based white quantum dot light-emitting diodes (QD-LEDs). The device was fabricated with a structure of ITO/PEDOT:PSS/PVK/QDs/TPBi/LiF/Al using synthesized ZnS:Al QDs which has 393 nm of peak wavelength and sub peaks in visible wavelength. White emission with high color rending index (CRI) was achieved by the combination of blue emission from PVK and ZnS:Al QDs, electroplex emission at the interface between PVK and ZnS:Al QDs, and Al traps/defects emission, which are controlled by electrical aging effect. The characteristic of our device shows the potential for spectrum tunable and Cd-free white QD-LEDs in the near future.

Electrical ageing effects on dielectric properties of polymethyl methacrylate

By combining the techniques of dielectric relaxation spectroscopy (DRS), measurement of both ac and dc conductivities, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), we have explored the effect of electrical ageing on poly (methyl methacrylate) (PMMA) films at temperature between 0 °C and 80 °C in the frequency range of 1 Hz–107 Hz. These results are discussed and correlated to FTIR and SEM observations.

The Photo‐Stability of Polymer Solar Cells: Contact Photo‐Degradation and the Benefits of Interfacial Layers

AbstractThe organic/electrode interfaces in organic solar cells are systematically studied for their light, heat, and electrical stability in an inert atmosphere. Various extraction layers are examined for their effect on device stability, including poly(3,4‐ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and MoO3 for hole extraction layers, as well as LiF, Cs2CO3, and lithium acetylacetonate (Liacac) for electron extraction layers. The organic/metal interface is shown to be inherently photo‐unstable, resulting in significant losses in device efficiency with irradiation. X‐ray photoelectron spectroscopy measurements of the organic/aluminum interface suggest that the photo‐induced changes are chemical in nature. In general, interfacial layers are shown to substantially reduce photo‐degradation of the active layer/electrode interface. In spite of their photo‐stability, several interfacial layers present at the active layer/cathode interface suffer from thermal degradation effects due to temperature increases under exposure to light. Electrical aging effects are proven to be negligible in comparison to other major modes of degradation.

P‐124: Effect of Electrical Aging on Reliability of Solution In Organic Light Emitting Diode

AbstractWe applied voltage on fabricated OLED with electrical aging in order to investigate the reliability of OLEDs. According to aging times, the decrease of initial capacitance by electrical stress because of the increasing the series resistance and decreasing the carrier doping density of emission states caused by moving fixed charge.

Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

In situ polymerized polyimide/TiO2 (PI/TiO2) nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz–106 Hz by an impedance analyzer (Agilent 4294A) at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.

Physical Properties and Electrical Aging Effects in Fe3+/Nb5+ Hybrid-Doped Barium Titanate Ceramics

It is well known that acceptor and donor doping results in opposite ferroelectric aging effects; however, the aging effects in hybrid-doped (acceptor+donor) materials has remained mysterious. Thus, the aging behavior of dielectric and ferroelectric properties in Fe 3+ /Nb 5+ hybrid-doped BaTiO 3 ceramics was investigated in this study. The concentration of acceptor dopant (Fe 3 + ) was fixed at 1 mol%, while that of donor dopant (Nb 5+ ) was varied from 0.5–2.0 mol%. The SEM and XRD techniques were used to study the microstructure and phase formation, respectively. The results showed that the dielectric properties of all de-aged samples decreased exponentially with time. The aged samples with 0.5 and 1.0 mol% Nb 5+ obviously showed constricted hysteresis loops, while those with higher concentration of Nb 5+ (1.5–2.0 mol%) showed normal hysteresis loops. The explanations based on the effects of defect dipole were discussed.

Field emission properties of silicon field emitter arrays with volcano-shaped gate structure

Field emission properties of silicon field emitter arrays (Si-FEAs) with sputtered gate structures were described and analyzed about two different tip structures surrounded by volcano-shaped gates. The resulted field emission characteristics showed that some of the emitted electrons are diverted to the gate structure because of the asymmetrical geometry of fabricated Si-FEAs with volcano-shaped gate structures. However, although the gate structures of fabricated FEAs had fragile and non-uniform edged shapes as a result of the shadow effect during sputtering and lift-off process in ultrasonic bath, it was possible to obtain stable field emission properties as a result of electrical aging effects on the edge of the non-uniform gate electrode as well as the surface of silicon tip after repeated measurements. From the Fowler–Nordheim (F–N) plots and F–N equations, it was confirmed that the field enhancement factor was abruptly changed through the electrical aging and was more influenced in case of the volcano-shaped lateral tip structure.

Electrical ageing of carbon nanotube composite cathode layers

Effect of electrical ageing (EA) on the field emission parameters of thin multiwall carbon nanotube composite (t-MWCNTs-composite) was studied. Initially, t-MWCNTs were mixed with α-terpineol and ethyl cellulose and subjected to three roll milling process to obtain t-MWCNTs-composite. Following this, the composite was screen printed on a conducting substrate, annealed for 10 min and employed to the electrical ageing process for a period of 6 h. The ageing, on each cathode layer, was repeated for five times and J– E characteristics have been collected before and after each ageing attempt. The analysis revealed that, the magnitude of threshold turn-on-field gradually increased from its virgin value of 1.223 to 1.968 V µm − 1 and corresponding mean field enhancement factor, γ m, gradually decreased from 2700 ± 210 to 1940 ± 30 with a sequential increase in the ageing attempts. The degradation rate, δ J/δ t, estimated for untreated and EA samples, indicated that the magnitude of δ J/δ t reached to an equilibrium value of ~ 0.785 μA cm − 2 min − 1 , which shows a stable emission state of the emitters. To investigate the effect of EA on the physical state of the emitters, a few virgin and all EA samples were subjected to scanning electron microscopy, micro Raman spectroscopy and X-ray photoelectron spectroscopy. The details of the analysis are presented.