Wire Insulation Research Articles

전기배선에서 과전류와 포화시간을 입력변수로 갖는 퍼지기반 전기화재가능성 분석

The study is aimed to develop fuzzy logic system that has overcurrent and saturation time as input variable and possibility of electrical fire as output variable by making bad conductor area with physical damage to indoor wiring. Most previous studies focused on thermal characteristics depending on the current size and no study considered the current size and saturation time at the same time. Therefore, the paper made into account current value and saturation time together. To this end, it created bad conductor area half the size of IV conductor (1.6 mm) on purpose and transmit electrical current from 10A to 60A by unit of 2A to find out the thermal characteristics and saturation time for current. Based on the data that came out, the study applied fuzzy logic and established the current and saturation time as input variable and chance of fire as output variable. As a result, the center of area of the system that depended only on the existing current value was 75 while the system that applied both current and saturation time presented the chance of fire at 92. It is found that the chance of bad conductor area and deteriorated insulation of electrical wire had current and saturation time as important variables. The data can be used as basic data like deteriorated wire insulation or operation features of circuit breaker in investigating the cause of electrical fire.

Transport in selectively magnetically doped topological insulator wires

We study the electronic and transport properties of a topological insulator nanowire including selective magnetic doping of its surfaces. We use a model which is appropriate to describe materials like Bi$_2$Se$_3$ within a k.p approximation and consider nanowires with a rectangular geometry. Within this model the magnetic doping at the (111) surfaces induces a Zeeman field which opens a gap at the Dirac cones corresponding to the surface states. For obtaining the transport properties in a two terminal configuration we use a recursive Green function method based on a tight-binding model which is obtained by discretizing the original continuous model. For the case of uniform magnetization of two opposite nanowire (111) surfaces we show that the conductance can switch from a quantized value of $e^2/h$ (when the magnetizations are equal) to a very small value (when they are opposite). We also analyze the case of non-uniform magnetizations in which the Zeeman field on the two opposite surfaces change sign at the middle of the wire. For this case we find that conduction by resonant tunneling through a chiral state bound at the middle of the wire is possible. The resonant level position can be tuned by imposing an Aharonov-Bohm flux through the nanowire cross section.

In-surface confinement of topological insulator nanowire surface states

The bandstructures of [110] and [001] Bi2Te3 nanowires are solved with the atomistic 20 band tight binding functionality of NEMO5. The theoretical results reveal: The popular assumption that all topological insulator (TI) wire surfaces are equivalent is inappropriate. The Fermi velocity of chemically distinct wire surfaces differs significantly which creates an effective in-surface confinement potential. As a result, topological insulator surface states prefer specific surfaces. Therefore, experiments have to be designed carefully not to probe surfaces unfavorable to the surface states (low density of states) and thereby be insensitive to the TI-effects.

A spin filter transistor made of topological Weyl semimetal

Topological boundary states (TBSs) in Weyl semimetal (WSM) thin film can induce tunneling. Such TBSs are spin polarized inducing spin-polarized current, which can be used to build a spin-filter transistor (SFT) in spintronics. The WSM thin film can be viewed as a series of decoupled quantum anomalous Hall insulator (QAHI) wires connected in parallel, so compared with the proposed SFT made of QAHI nanowire, this SFT has a broader working energy region and easier to be manipulated. And within a narrow region outside this energy domain, the 2D WSM is with very low conductance, so it makes a good on/off switch device with controllable chemical potential induced by liquid ion gate. We also construct a loop device made of 2D WSM with inserted controllable flux to control the polarized current.

Peculiarity of Determination of Economic Current Density Values for 6 – 35 kV Power Lines under Modern Conditions

The paper studies the issues concerning the updating of standardized values of economic current density due to the change of price indices in the modern Russian economy. Results of economic current density determination for 6 – 35 kV power lines based on minimal discounted costs in terms of modern cost data are presented. Assessment of responsitivity of economic current density values to the variation of technical and economic factors influencing them has been performed. Moreover, economic current density values for cables insulated with cross-linked polyethylene and self-supporting insulated wires which are not presented in the Electrical Installation Code have been obtained. Changes in electric power cost and time-dependant changes of electric load are taken into consideration in the specified values.

Permittivity and electrical breakdown response of nylon 6 to chemical exposure

Environmental stress such as unintended exposure of aircraft wire insulation to aviation-related fluids is one cause of wire aging that increases the risk of electrical failure. In this paper, the dielectric properties of nylon 6, a common wire insulation material, were investigated under chemical exposure for up to 8 days in six fluids: distilled water, cleaning fluid, isopropyl alcohol, deicing fluid, jet fuel and hydraulic fluid. Real permittivity e') and dissipation factor (D) of aged samples were measured using an LCR meter over frequency range from 100 Hz to 1 MHz in an ambient environment (23 °C). It was found that e′ and D of aged nylon 6 exhibit distinct shifting behavior according to the polarity of the fluids in which it is immersed. Immersion in polar fluids gives rise to a strong effect of fluid absorption on the increase of polarizability of nylon 6, showing significant increase in e′ and D, along with moving of relaxations to higher frequencies. Electrical breakdown strength of nylon 6 was also observed to reduce dramatically following exposure to polar fluids. A two-parameter Weibull distribution was applied to analyze the distribution of electrical weak sites in chemically-aged nylon 6 and it is concluded that a different electrical breakdown mechanism could be responsible for the narrower distribution observed after polar chemical exposure than for the pristine material. Nylon 6 displayed resistance to aging in non-polar fluids, showing no significant change in complex permittivity and electrical breakdown strength.

Automatic Color Inspection for Colored Wires in Electric Cables

In this paper, an automatic optical inspection system for checking the sequence of colored wires in electric cable is presented. The system is able to inspect cables with flat connectors differing in the type and number of wires. This variability is managed in an automatic way by means of a self-learning subsystem and does not require manual input from the operator or loading new data to the machine. The system is coupled to a connector crimping machine and once the model of a correct cable is learned, it can automatically inspect each cable assembled by the machine. The main contributions of this paper are: (i) the self-learning system; (ii) a robust segmentation algorithm for extracting wires from images even if they are strongly bent and partially overlapped; and (iii) a color recognition algorithm able to cope with highlights and different finishing of the wire insulation. We report the system evaluation over a period of several months during the actual production of large batches of different cables; tests demonstrated a high level of accuracy and the absence of false negatives, which is a key point in order to guarantee defect-free productions.

The Effects of Partial Replacement of Virgin Polyethylene (vPE) with Recycled Polyethylene (rPE) in vPE/rPE/Ethylene Propylene Diene Terpolymer (EPDM) Blends: Thermal Properties and Swelling Behaviour

Studies on the thermoplastic elastomers (TPEs) had been extensively done. The incorporation of recycled materials into the TPEs formulation had been analysed, particularly involving recycled plastic due to its properties. The effects of partial replacement of virgin polyethylene (vPE) with recycled polyethylene (rPE) on the thermal properties and swelling behaviour of vPE/rPE/EPDM blends were studied. The discarded polyethylene used in the study was obtained from local wire insulation industry. The thermal properties and swelling behaviour of the blends were analyzed. Results show that increasing of sulfur loading had improved the thermal stability of the blends. The swelling percentage and swelling index of vPE/rPE/EPDM blends also decreased, inversely proportional to the increasing of sulfur loading. Thus, the increased incorporation of sulfur loading had improved the chemical and oil resistance of the blends.

INVESTIGATION ON THE EFFECT OF COMPOSITION OF CALCIUM CARBONATE, CPW AND DOP ON TENSILE STRENGTH OF PVC WIRE JACKET HAVING 45 % PVC RESIN

One of the biggest challenges in wire insulation industries is the proper governance of its raw materials to form the standardized product. The use of plasticizers has been well investigated and their utilization is very abundant. The ratio of CaCO3, CPW and DOP plays a very important role in determination of the tensile strength of PVC insulation. This paper focuses on the effect of CaCO3, CPW and DOP on the tensile strength of the PVC compounding having PVC resin at hold value of 45%. Unlike other papers this paper enumerates the effect of several components of the mixture simultaneously. The CaCO3 content ranges from 23.50-29.82 %, CPW ranges 8.7-13.04 % and DOP 10.0-15.04 % by weight. The optimum results for Ultimate Tensile Strength came out with 23.52% CaCO3, 13.0% CPW and 14.75% DOP.

Curie temperature controlled self-healing magnet–polymer composites

Abstract

Thermal Characterization of Electrical Wires and Insulation Operated in Variable Frequency Mode

NFPA 70 provides guidelines on conducting wire size rating for different service current ratings. Additionally, an engineering calculation method is provided for unusual cases. While not apparent, these guidelines are valid only for 60 Hz type frequencies. Electrical conductors have increased Joule heating with higher frequency operation because of electromagnetic effects like skin and proximity effects and the increase of total reactance of conductors and appliances. Until now, those effects have not been a fire safety concern, but the large increase in high power applications using frequencies higher than 60 Hz in variable frequency drives, also called adjustable frequency drives or simply “AC drives”, to control the operation of large motors, changes this. While research has improved the performance of motors and AC drives, there has been relatively little research on the thermal effects and fire safety implications of these systems. In this paper we show that conductors used with common variable frequency power electronics have heat dissipation rates that can be up to 50% larger than what is calculated according to the standard formulas used for 60 Hz systems. Using accelerated aging models for the wire insulation it is shown that these increases in heat dissipation rate can reduce useful cable life by a factor of two or more.

The chronic challenge-new vistas on long-term multisite contacts to the central nervous system.

The chronic challenge-new vistas on long-term multisite contacts to the central nervous system.

PCDD/Fs in air and soil around an e-waste dismantling area with open burning of insulated wires in south China.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air and farmland soil sampled in 2006 around an e-waste dismantling area with open burning of insulated wires in Longtang in south China were investigated. The total toxic equivalent concentrations of PCDD/Fs were 3.2-31.7 pg/m(3) in air and 5.8 12.4 ng/kg in farmland soil at an e-waste site and 0.063-0.091 pg/m(3) in air at a background site. PCDD/Fs in the air at the e-waste site were characterized with dominant 1,2,3,4,6,7,8-HpCDF and OCDF and higher concentrations of furans than dioxins, suggesting open burning of insulated wires was likely to be the main source of PCDD/Fs. Compared with the results in this study, the level of PCDD/F tended to lessen with the average TEQ concentration decreasing by 41 % and the pattern changed to be dominated by OCDD in the air of Longtang in 2010 when insulated wires were openly burned in only a small scale. Our results indicate that the lower chlorinated congeners with higher vapor pressures have enhanced atmospheric transport tendencies.

Modelling of fault detection in electrical wiring

Electrical wiring and cables, in many cases buried deep, in many systems and environments suffer damage. In some cases the damage only affects wire insulation and is not usually detected under normal operating conditions. This study discusses computer modelling of electrical wires, based on time-domain reflectometry using trains of successive pulses which were used in order to develop techniques and test procedures that would lead to identification of these types of faults. This study shows detailed simulations of defects in insulation of electrical wires and in cable shields, using dedicated electromagnetic modelling computation software. The results of simulations were compared with those obtained in experimental measurement for wires and cables of several metres in length. Comparison of the analysed measurement results for this novel technique shows clear indication of its relevance to flaw detection in electrical wires, guided through simulation.

Stiffness-matched segmented metallic guidewire for interventional cardiovascular MRI

Background Conductive guidewires and intravascular catheters are at risk of RF-induced heating under MRI [1]. Heating is found predominantly at the tip of conductive wires [2], and is modulated by wire diameter, length and insulation thickness [3]. Non-conductive materials, such as polymer, impart unsatisfactory mechanical properties on guidewires in terms of flexibility, stiffness, and torquability, for navigating tortuous cardiovascular structures and for safely delivering catheter devices.

Analysis of thermal characteristics of electrical wiring for load groups in cattle barns.

The purpose of the current study is to analyze the thermal characteristics of electrical wirings depending on the number of operating load by connecting four types of electrical wirings that are selected by surveying the conditions for the electric fans, automatic waterers and halogen warm lamps that were installed in cattle barns in different years. The conditions of 64 cattle barns were surveyed and an experimental test was conducted at a cattle barn. The condition-survey covered inappropriate design, construction and misuse of electrical facility, including electrical wiring mostly used, and the mode of load current was evaluated. The survey showed that the mode of load current increased as the installation year of the fans, waterers and halogen lamps became older. Accordingly, the cattle barn manager needed to increase the capacity of the circuit breaker, which promoted the degradation of insulation of the electrical wires’ sheath and increased possibility for electrical fires in the long-run. The test showed that the saturation temperature of the wire insulated sheath increased depending on the installation year of the load groups, in case of VCTFK and VFF electric wires, therefore, requiring their careful usage in the cattle barns.

PolyOne unveils foaming additive for fluoropolymer wire insulation; opens Indian masterbatch plant

Connecticut-based PolyOne Colorant Chromatics has launched a new chemical foaming solution for fluoropolymer wire insulation that reportedly can reduce part density while enhancing the stability and efficiency of the manufacturing process, the company claims. This advanced additive also enables wire manufacturers to preserve electrical properties while reducing insulation thickness and raw material consumption through a consistent closed cell structure, according to PolyOne.

부가적으로 설치된 장치 결함으로 인한 차량화재 사고사례 분석

This paper deal with due to the additional equipment established on the vehicle fire accident cases. Recently, vehicle was recognized as other living spaces and it was increasing installation of additional devices such as a black box, multivision, additional battery and so on. However, these additional devices were established on the vehicle by non-specialists such as the general public user or manufacturing and distributors of additional devices since the vehicle factory. Resulting from the additional equipments due to installation errors in these additional equipments connected to the electrical wiring insulation damage or electrical breakdown occurs, and finally leading to a fire caused by the additional equipments. Therefore, additional equipment established on the vehicle due to a fire in order to prevent accidents during the manufacturing process of these devices are installed. If not installed unless the manufacturing process, the installation of additional equipments established by professional who knows the vehicle structure that will be able to prevent the fire.

Estimation of winding insulation resistance to the corona discharges

This article presents test results of enameled winding wires, characterizing an insulation electrical and mechanical strength. Standard and original test methods were used. Note that existing standard test methods do not estimate enamel insulation resistance to the electrical loads under winding operation of variable-speed drive. We show that estimation of wire corona resistance can be done by high frequency electrical impulse testing. Wire insulation plays the main role of reliability of insulation system.

Aging Tests on Nanostructured Enamels for Winding Wire Insulation

Early failures due to stator insulation breakdown are still frequently experienced in industrial applications where low-voltage induction motors are fed by adjustable speed drives. Such events are caused by the quick erosion of organic insulating materials used in Type I random wire wound windings when the inception of partial discharges (PDs) is triggered by the severe electrical stress produced by fast switching electronic converters. The present experimental work provides some interesting results about the medium-long-term behavior of nanostructured organic-inorganic enamel-based compounds in the presence of PDs. The outcome evidences that polymeric-nanocomposite enamels may provide a strong enhancement of the duration; thus, they could be proficiently adopted as the stator winding primary insulation.