Dielectric Withstand Voltage Research Articles

Satisfaction-Based Multiobjective Optimization of the Design of a 65 GHz Millimeter-Wave Connector

It is difficult to simultaneously ensure the radio frequency (RF) performance and mechanical strength of 65 GHz millimeter-wave connectors. To address this, satisfaction-based multiobjective method for connector design optimization is proposed. An optimization model is developed for the structural dimensions of 65 GHz millimeter-wave connectors to minimize the voltage standing wave ratio, insertion loss, and deflection and maximum stress of the center conductor. The proposed optimization model concurrently satisfies the design requirements in terms of characteristic impedance, transmission frequency, and dielectric withstanding voltage. The model is optimized by innovatively using the multiobjective chaotic optimization algorithm in microwave finite-element simulations. The resulting optimal structure satisfies all performance requirements, thereby proving the rationality and feasibility of the proposed method. Moreover, this study establishes a novel design for other microwave devices to solve the problem of multiple performance index restrictions.

Ultrahigh energy density of poly(vinylidene fluoride) from synergistically improved dielectric constant and withstand voltage by tuning the crystallization behavior

The stretched PVDF films exhibit a substantial and concurrent increase in both permittivity and breakdown strength. The microstructure–property relationship is investigated to provide guidance in PVDF polymers for high-energy storage applications.

Statistical Investigation of Lightning Impulse Breakdown Voltage of Natural and Synthetic Ester Oils-Based Fe3O4, Al2O3and SiO2Nanofluids

The characteristics of lighting impulse breakdown voltage (LI-BDV) constitute key performance indicators of insulating materials, especially in insulations based on liquids and liquid-paper for high voltage applications. Encouraged by environmental policies worldwide, new insulating liquids have been developed in recent years. Among these are natural and synthetic esters that are currently considered as potential substitutes for traditional mineral oils due to their environmentally friendly properties. Recent technological advances have shown that the addition of specific nanoparticles (NPs) to insulating liquids can improve both the dielectric withstand voltage and the thermal behavior of liquid insulations. This paper examines the effects of some NPs on the negative LI-BDV of natural and synthetic ester liquids, namely MIDEL 1204 and MIDEL 7131, respectively. The used NPs are Fe3O4, Al2O3 and SiO2. The LI-BDV measurements are executed in accordance with IEC 60060 standard, and the breakdown voltage with 1% probability risk (i.e., the lowest possible breakdown voltage) was also estimated. The experimental results showed that these NPs improved the LI-BDV of both synthetic and natural ester liquids and an optimal concentration of NPs can be determined. Statistical analysis was also performed to check the compliance of the experimental results with the most common probability distributions, normal and Weibull distributions.

Research on Ceramic Capacitor Automatic Test Application Technology

In order to improve the detection efficiency and quality of reliability screening for electronic component in military industry such as aerospace and aeronautics, and eliminate the hidden safety hazards caused by manual inspection operation, the ceramic capacitor automatic test technology was applied to the electrical performance testing of reliability screening process. An new original automatic detection system by using auto test technology of automatic loading and unloading, instrument automation control and parallel testing was designed and developed to realized one-key automatic measurement of capacitor four parameters such as capacity accuracy, loss, insulation resistance and dielectric withstand voltage. It solved the test quality problem that test data could not be automatically recorded and avoided the harm caused by high voltage and short circuit in the detection process. Finally, with the practical application and test, the efficiency and quality of detection process was improved.

Re-Makeable Joint With Insulation for REBCO Superconductor Cables

Composite Technology Development, Inc., in partnership with the Plasma Science and Fusion Center (PSFC) at MIT, recently developed and demonstrated a re-makeable, insulated high temperature superconductor (HTS) cable joint for a Twisted Stacked-Tape Cable. The prototype joint exhibited low tape-to-tape resistances (∼400 nΩ) with critical current through the joint for most tape pairs matching that of the as-supplied conductor tape ( I c = 142 A). The best performing insulation scheme showed dielectric withstand voltage in excess of 10 kV. Disassembly and reassembly of the joint showed no degradation in performance.

Fabrication, characterization, properties and theoretical analysis of ceramic/PVDF composite flexible films with high dielectric constant and low dielectric loss

Calcium barium zirconate titanate (Ba0.95Ca0.05Zr0.15Ti0.85O3, BCZT) ceramic particles were prepared by a conventional solid-state method. BCZT powders were modified by dopamine through a chemical coating method. The composite flexible films based on dopamine@BCZT and polyvinylidene fluoride were fabricated via a solution casting method. The microstructure and morphology were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. A precision impedance analyzer and a dielectric withstand voltage test were used to test the dielectric constant, loss tangent, and breakdown strength. TEM results showed that dopamine was uniformly coated on the surface of BCZT particles with an average thickness of 20 nm. SEM results showed that the ceramic particles were dispersed homogeneously in the matrix. The dielectric constant increased with the increase of BCZT contents, while the loss tangent remained constant in the frequency range of 103 to 105 Hz. Different theoretical models were employed to predict the effective dielectric constants of the composite films, and the estimated results were compared with the experimental data. Weibull distribution was used to analyze the dielectric breakdown strength, and the results showed that the breakdown strength decreased then stayed over 60 kV mm−1.

Characterization of Inkjet-Printed Silver Patterns for Application to Printed Circuit Board (PCB)

In this paper, we describe the analysis of inkjet-printed silver (Ag) patterns on epoxycoated substrates according to several reliability evaluation test method guidelines for conventional printed circuit boards (PCB). To prepare patterns for the reliability analysis, various regular test patterns were created by Ag inkjet printing on flame retardant 4 (FR4) and polyimide (PI) substrates coated with epoxy for each test method. We coated the substrates with an epoxy primer layer to control the surface energy during printing of the patterns. The contact angle of the ink to the coated epoxy primer was 69˚, and its surface energy was 18.6 mJ/m². Also, the substrate temperature was set at 70℃. We were able to obtain continuous line patterns by inkjet printing with a droplet spacing of 60 ㎛. The reliability evaluation tests included the dielectric withstanding voltage, adhesive strength, thermal shock, pressure cooker, bending, uniformity of line-width and spacing, and high-frequency transmission loss tests.

The Effectiveness of Screening Techniques for Revealing Cracks in High Volumetric Efficiency MLCCs

Multilayer ceramic capacitors (MLCCs) constitute the majority of components used in electronic assemblies and most of their failures are related to cracks. It is often assumed that dissipation factor (DF), insulation resistance (IR), and breakdown voltage (VBR) are characteristics that are sensitive to the presence of mechanical defects, and screening of capacitors by measurements of these characteristics, and by dielectric withstanding voltage (DWV) testing assures high quality products. This work analyzes the effectiveness of these screening techniques for revealing cracks in high-volumetric efficiency, low-voltage ceramic capacitors. Various types of class II dielectric capacitors with rated voltages from 6.3 V to 100 V, and capacitances from 0.1 μF to 100 μF from different manufactures were used in this study. Fractures in the parts were introduced mechanically and by thermal shock stress. It has been shown that cracking results in relatively minor variations of capacitance and DF. Absorption currents prevail over leakage currents during standard IR measurements at room temperatures, and at high temperatures the intrinsic leakage currents exceed substantially leakage currents caused by cracking thus masking the presence of defects. Analysis of distributions of breakdown voltages in normal capacitors and capacitors with cracks showed that the majority of defective capacitors can pass the DWV testing. New, more effective methods of electrical testing and possible improvement of the existing techniques are discussed.

The Study of Motor Winding Testing System for Inter-Turn with 30kV

This paper designed a motor winding testing system, it can do the dielectric withstand voltage test of inter-turn under 30kV.The system can communicate effectively between PC and machine, by using the PC's powerful capacity of process data and PLC's better stability and the Labview's convenient UI. So the system has real-time data collection, preservation, analysis and other characteristics. This system is able to achieve factory testing and type testing of the motor windings facilitating. Various performance indicators were stable and reliable by field test during a long time.

The Method of 1394b Bus Transmission Cable Electrical Characteristics Testing

This paper presents a method of 1394b bus transmission cable electric parameters testing and provides a reliable way in selecting transmission cable. This paper introduces the IEEE-1394b protocol for transmission cable of electric parameters and requirements. We set up platform for 1394 cable testing, taking four kinds of 1394 bare wire cable and cable with Quadrax connector for dielectric withstanding voltage, differential impedance and so on. Using this test method can accurately reflect the 1394 cable’s electrical characteristics.

Breakdown voltages in ceramic capacitors with cracks

Breakdown voltages in 27 types of virgin and fractured X7R multilayer ceramic capacitors (MLCC) rated to voltages from 6.3 to 100 V have been measured and analyzed to evaluate the effectiveness of the dielectric withstanding voltage (DWV) testing to screen-out defective parts and get more insight into breakdown specifics of MLCCs with cracks. Fractures in the parts were introduced mechanically and by thermal shock stress. To simulate exposure of internal electrodes to environments in fractured parts, breakdown testing was carried out also on cross-sectioned and polished capacitors.

Development of a 13.2 kV/630 A (8.3 MVA) High Temperature Superconducting Fault Current Limiter

This paper deals with fabrication and development of a high temperature superconducting (HTS) fault current limiter (FCL) based on YBCO coated conductor (CC) wire for distribution systems. The capacity of the developed HTS FCL is 8.3 MVA and its rated voltage is 13.2 kV which corresponds to a three-phase power equipment voltage class of 22.9 kV. Tests of the developed prototype HTS FCL were conducted at Korea Electrotechnology Research Institute (KERI) accredited as a testing laboratory by the Korea Laboratory Accreditation Scheme (KOLAS). A short-circuit test and an AC dielectric withstand voltage test for the HTS FCL were conducted under sub-cooled liquid nitrogen (LN2 ) conditions of 3 bar and 65 K. The magnitude of an asymmetric short- circuit current without FCL reached 30 kApeak in a short-circuit test. The superconducting coil quenched instantaneously after the fault, and the magnitude of the fault current was limited to 3.6 kApeak within quarter cycle by the developed resistance of the superconducting coil. An AC dielectric withstand voltage test was performed, and the HTS FCL successfully withstood 143 kV for 1 minute. Also, it was found that there was no electrical or mechanical damage on the superconducting coil after the tests.

Dielectric Withstand Voltage Tests and Test Conversion Factors for Oil-Filled Transformers

Dielectric withstand voltage tests to verify oil-filled transformer insulation performance are in most cases carried out using two to three types of tests from lightning impulse (LI), switching impulse (SI) and power frequency (PF) withstand voltage tests based on economical factors and past achievements. Test conversion factors (TCF) are used to evaluate whether the tests cover overvoltages not directly dealt with in tests and the omitted tests. In this paper, insulation characteristics for LI, SI, and PF (AC) are first organized including the recent ones. Several sets of TCF are next calculated based on these characteristics, compared with TCF in present standards, and representative values are then derived. Finally, the dielectric withstand voltage tests specified in present standards are compared using the representative TCF, and the AC withstand voltage test was found to be the severest test overall.

Effect of Puffer Volume and Operating Force on Dielectric Recovery Performance in Thermal Puffer-Type Gas Circuit Breaker

In order to investigate the influence of puffer volume V/sub P/ and operating force to dielectric performance of GCB at current interruption, we calculated the prospective dielectric withstand voltage V/sub W/ between arcing contacts. The withstand voltage was calculated by the electric field strength appeared on arcing contacts and the allowable electric field strength E/sub W//sup */ of hot gas due to thermal puffer action. We could clarify that large initial puffer volume V/sub P/ can increase withstand voltage V/sub W/ at current breaking point and also that an optimum point exists in operating force F. For example, it was found that in case of the operating force of 1000 kgf, the puffer volume V/sub P/ of 1.2 liter would be best choice in the interrupting condition of i=50 kA and arcing time of 1.35 cycle.

Significant increase of the dielectric performance of plastic sealed telecom relays

Initialized by Bellcore, the dielectric requirements on telecom relays have been significantly increased in recent years. In parallel the dimensions of the relays had to become smaller and smaller in order to save space on printed circuit boards in electronic equipment. By filling plastic sealed relays with the electro-negative gas sulfur-hexafluoride (SF/sub 6/), the dielectric withstand voltage of the relays was increased by a factor of 2 compared to that with a normal gasfilling with nitrogen. This method allows one to guarantee a lightning impulse withstand voltage of more than 3500 V between coil and contacts and more than 2500 V between open contacts without increasing distances in the design of the relay. The consequences of a SF/sub 6/-filling on the life endurance of a relay were investigated extensively. The results show that the switching range of SF/sub 6/ filled relays could even be extended compared to relays with a N/sub 2/-filling. The gas tightness of the relay housing is sufficient to guarantee an SF/sub 6/ loss of less than 10% during a lifetime of more than 25 years even under severe climatic conditions. The effects on the environment of using SF/sub 6/ in telecom relays turn out to be not significant at all.

High-voltage and partial discharge testing techniques for space power systems

Partial discharge (PD) detection techniques are reviewed, focusing on application in the aerospace industry. The discussion covers dielectric withstand voltage test, causes of high-voltage failures in flight hardware systems and how PD testing can detect incipient problems, and high-frequency PD test methods and applications.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dielectric Performance of Improved Gas Insulated Bushing for UHV Gis

This paper describes a improved gas insulated bushing for ultra high voltage (UHV) SF6 gas insulated switchgear (GIS) which contains a simple capacitor core inside a porcelain housing. The effects of arrangement and capacitance of the capacitor core on the voltage distribution along the external porcelain surface were analyzed, and a 2/3 scale model of a prototype UHV gas insulated bushing (6.7m porcelain housing) was developed. Characteristics tests of the voltage distribution and dielectric withstand voltage indicated that the voltage distribution was greatly improved and the dielectric withstand voltage of the switching impulse under wet conditions was enhanced about 30% compared with a conventional gas insulated bushing.

Silicon Oxide Micromodule Capacitors

Silicon oxide capacitors have been developed on micromodule wafers (O. 3lO-in. sq. with three termination notches per side). Each microelement contains 1, 2, 3, or 4 capacitors with values of 1120 and 560, 180, 100 and 68 pf per capacitor, respectively. The 1120 pf capacitor is double layered. In addition to the general requirements of microelements and micromodules, some of the more important specifications these capacitors must meet are: dissipation factor (DF) not exceeding 0.015, insulation resistance (IR) at 50 volts exceeding 10,000 megohms (25°C) and 750 megohms (125°c), 50 WVDC and 150 volts dielectric withstanding voltage (DWV), \Delta not exceeding + 15% (-55° to 125°C), no breakdown during or after a short term life test of 72 hours at 125°C while stressed at 150 volts, and a long term life test of 2000 hours at 125°C and 100 volts after which DF should not exceed 0.03 and IR should exceed 3000 megohms (room temperature) and be not less than 500 megohms (125°C). The capacitors are non-polar with vacuum deposited A1 electrodes and silicon oxide (largely monoxide) dielectric. They are fabricated in a microcircuit jig that processes 32 microelements simultaneously and 192 microelements during one vacuum cycle. Both the A1 and SiO are deposited at the monitored and controlled rate of 50 A/sec. The thicknesses of electrodes and dielectric are 5000 and 12,500, respectively. Wafer temperature during deposition is about 170°C and chamber pressure is 1-4x10-5torr during A1 evaporation, and 0.6-1x10-5 torr during SiO evaporation. The SiO evaporator design is important; a baffled Ta box has proven satisfactory. Deposition masks were made from 0. 005-in. spring steel by photoresist techniques. Capacitors deposited on unglazed alumina wafers had DF readings of approximately 0.3; undercoating with SiO or polishing the wafers did not prove effective in reducing the DF appreciably. Glazing' the alumina prior to capacitor deposition lowered the DF to about 0.04. Two approaches to glazed elements were equally successful: (1) a glass frit fired onto an unglazed, metallized wafer; (2.) metallizing applied to a glazed wafer. The second approach has been adopted. Capacitance is uniform to within ±5% and DF to within ± 10%. It was found that heat treatment in air at 250°C for at least 48 hours lowered the DE to less than 0.008, lowered the capacitance by about 10%, and increased IR to over 10,000 megohms without causing detrimental electrode-land reactions. Presumably, oxygen diffuses into the dielectric converting it to SiOx(1< x <2) and lowering its dielectric constant. The units are very stable, maintaining their capacitance, DF, and DWV values for months while stored at 25°C in ambient atmosphere. **