Cable Characteristics Research Articles

Effect of SrFe12O19 Orientation in the Inner Semi-conductive Layer on Charge Accumulation Characteristics of HVDC Cable

A method of space charge suppression for high-voltage direct current (HVDC) cable is proposed by the modification of the semiconductive layer. In this work, the magnetic particle of SrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> is used to modify the semiconductive shielding layer, and the effect of SrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> orientation on the charge accumulation of the insulation layer has been studied. First, the semiconductive composite with different SrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> contents is prepared and their physicochemical properties are characterized. Second, the effect of the SrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> orientation in the semiconductive layer and the doping contents on the charge accumulation in the insulation layer is analyzed by measuring the resistivity and space charge. The experimental results show that a certain amount of SrFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sub> (≤10 wt%) can effectively reduce the positive temperature coefficient (PTC) effect, and the orientation can more effectively reduce the space charge injection from the metal wire core to the insulation layer, thus inhibiting the charge accumulation in the insulation layer. While when the content of magnetic particles is high, it will promote the second injection of the charges, leading to an increase of the charge accumulation. The work provides a new idea for space charge suppression of HVDC cable insulation layer.

Investigation of friction characteristics of control cables

Investigation of friction characteristics of control cables

Model of deformation growth dynamics during filled polymer materials mechanical tests under cable production conditions

With the introduction into highly filled halogen-free plastics production, the mechanical strength of which in operation directly depends on the flame retardant content and application technology, it becomes important to control the cable sheath mechanical characteristics in a fireproof design. Polymeric materials and their compositions are viscoelastic materials for which the mechanical properties depend on the stress time. The results of estimating the deformation samples rate elongation from the uniaxial stretching time at different dilution rates of the clamps in the mechanical characteristics determining process for halogen-free cable plastics in regulatory tests under production conditions are presented. It is shown that the inner and outer layers of the halogen-free plastic cable sheath have significantly different values of the plasticity normative parameter: differences evidence in the polymer structure in the inner and outer layers of the sheath due to the forced deformation process during extrusion, which is forced polymer structure orientation. Elongation relative deformation experimental dependences δL(t) of the samples on the uniaxial stretching time at different clamps dilution speeds are given, which illustrate confirmed by a large data array the dependencies shape reproducibility δL(t) for different in structure similar filled halogen-free polymers. The strain rate dependence model on tensile time as the sum of instantaneous-elastic, viscoelastic and instantaneous-plastic (irreversible) is proposed: dε/dt = λпр exp ( – t/λпр) + {∫ λ1 exp(–τ/λ1).exp[–(t–τ)/λ2]dτ]}/Δt. The appropriate parameter estimates of the named samples deformation components obtained by approximating the experimental data by the proposed model are given. The proposed model, firstly, explains the presence characteristic relative deformation maximum (t = tm) as a two interdependent deformation processes superposition with different aftermath λ. Secondly, it allows to specify the requirements for testing: with increasing the clamps dilution speed, the maximum time tm decreases significantly, respectively, the higher the clamps dilution speed, the smaller interval time Δt between a successive sample control section length measurements. This conclusion was experimentally confirmed for a specific material at a speed of 250 mm/min

Analysis of Transient Operating Characteristics of the 10 Kv Tri-Axial HTS Cable Under Fault Current

The Tri-axial high temperature superconducting (HTS) cable usually subjects to the impact of the fault currents in the power system. During the fault, a large amount of the Joule heat is generated, which may be damage cable. In this paper, an analysis model of electromagnetic thermal transient characteristics of the 10 kV/1 kA cable is built. The transient characteristics of the HTS cable are analyzed under a fault current of 15 kA rms lasting 0.14 s, and the current, resistance and temperature of the HTS cable are obtained. The maximum temperature of the HTS cable is 153.1 K under fault current. Meanwhile, the safe operating range of the HTS cable under the fault current of 15 kA to 25 kA is obtained. the analysis results will provide the theoretical basis for the quench protection and relay protection strategy of the tri-axial HTS cable in the Grid.

Transient overvoltage characteristics in submarine cables of multi-terminal flexible HVDC transmission system

The overvoltage transient characteristics of submarine cables are one of the key technologies for submarine power transmission. This article takes the submarine cable of Zhoushan Multi-terminal Flexible HVDC Transmission Project as the research object. The MMC-HVDC simulation models at both ends of converter stations are built in PSCAD. The parameters and equivalent models of the flexible HVDC cables are determined, and the submarine DC cable operating overvoltage is calculated by using statistical methods. The simulation results show that the maximum overvoltage of the submarine cable, that is, the maximum overvoltage of the conductor to sheath, the sheath to the armour, and the armour to the ground are 400 kV, 7.27 kV and 0.45kV respectively. The maximum overvoltage when it occurs faults on grid-side or valve-side appears in the middle of the submarine cable. Maximum overvoltage of HVDC single pole grounding fault appears at the connection point of land cable and submarine cable. The simulation results and the discovery of features in this article provide reference in the design, selection, and testing of submarine power transmission equipment.

Analysis and Methods for HTS DC Cables

High-temperature superconducting (HTS) DC cables with the merits of light weight, large capacity and low loss provide a novel power transmission method for future utility grid. In this paper, the electromagnetic characteristics of unipolar and bipolar coaxial HTS DC cables are compared by finite element simulation. Besides, the 3D magnetic flux density distribution characteristics of HTS DC cable are obtained. The method to investigate the influence of winding angle on HTS DC cable magnetic flux density is also applied to 3D HTS DC analysis.

Distributed fiber optic strain sensing of bending deformation of a well mockup in the laboratory

Well integrity is critical to the safety and success of subsurface energy exploration and management, as leakage of fluids from subsurface reservoirs is often induced by compromised wells. This study investigates bending deformation of a mockup of an oil/gas well that is subjected to loads expected in deviated wells under reservoir compaction and assesses the feasibility of utilizing distributed fiber optic strain sensing to monitor the deformation. A well mockup, which consists of outer and inner steel pipes with a cemented annulus, is tested under three-point bending loading and its strain and curvature development is monitored by Brillouin optical time domain reflectometry/analysis (BOTDR/A) as well as optical frequency domain reflectometry (OFDR). The primary objective of this research is to assess the strain sensing performance of newly fabricated fiber optic cables and to identify key cable characteristics which could improve the quality of distributed strain measurements with BOTDR/A. Results show that the tight-buffered cable is best suited for strain sensing as its maximum errors in the strain measurement were −36% and −24% against conventional sensors at the maximum elastic and plastic bending loads, respectively, whereas those of the non-tight-buffered cable were −45% and −71%, respectively. Similar trends were obtained in the bending curvature measurement. The detailed design of the tight-buffered cable is presented to elucidate key characteristics of such a cable, which will facilitate accurate distributed strain sensing in oil and gas wells.

A numerical investigation on quasi-static configuration and nonlinear dynamic response characteristics of marine towing cable

The towed seismic cable system is the main equipment of marine seismic exploration, which is a widely-used technique in oil and gas exploration. The towing cable connects the ship and the towed body, transmitting electricity and signals. The vibration of cable induced by the vortex shedding can affect the signal transmission and thus the exploration efficiency. This paper proposes a time-domain nonlinear numerical model to investigate the cable's dynamic response for deeper understanding the mechanism. A large amount of towing cases for a real-scale towing cable are designed. With the fundamental study on the quasi-static configuration, natural frequency and encountered speed of the cable, its nonlinear dynamic response characteristics are analyzed systematically. The overall dynamic response presents a mixture pattern of traveling wave and standing wave, and multi-modal participation can be readily captured. Besides, the variable cable weights, cable lengths, towing speeds and towed body weights all exert a significant impact on the Root Mean Square (RMS) displacement and excited frequency of the cable's vibration. Associated with VIV mechanism analysis, the response characteristics with different structural physical parameters and working condition parameters are explained reasonably.

Bench-scale experimental study on the fire behavior of electric cable arrays by considering different layouts

The effect of different cable layouts on the fire behavior of electric cable arrays was experimentally studied. The influence of external heat flux on cable fire characteristics was investigated. Several parameters for electrical cables such as the post-burning morphology, ignition time, heat release rate, peak heat release rate and total heat release were obtained. The results show that cable layouts could affect cable charring degrees according to the post-burning morphology. A linear relationship was found in the transformed form of time to ignition and radiant heat flux, and the critical radiant heat flux value for the single cable array appeared smaller than that for the other two layouts. The peak heat release rate for Cables A–D with the single array presents the increasing trend with an increase in radiant heat flux, while the two parallel and intersectional cable arrays present the different trends. Moreover, the total heat release values of Cables A–D in the different cable layouts were analyzed. This work provides the basic data and preliminary investigation to fire engineering of cable arrays with the different layouts.

Dynamic characteristics of deep-sea ROV umbilical cables under complex sea conditions

Ensuring the safety of umbilical cables is a core challenge in deep-sea robotics. The umbilical cable usually amplifies the motion amplitude of the mother ship owing to its elastic material. Under the joint action of the mother ship motion and ocean current, the strong internal force waves generated in the umbilical cable tend to cause serious accidents such as umbilical cable breakage. Based on the Kirchhoff rod theory, a dynamic model of an umbilical cable under complex sea conditions is established. The differential quadrature method and Newmark method are used to discretize the equation in the space and time domains. The characteristics of the umbilical cable under different conditions are analyzed. The results show that the amplitude amplification rate of the umbilical cable is directly proportional to the velocity of the ocean current and amplitude of the mother ship motion, and inversely proportional to the period of the mother ship motion. When the length of the umbilical cable changes, the amplitude amplification rate reaches a maximum at 3000 m.

Selection of process for aluminium separation from waste cables by TOPSIS and WASPAS methods

The separation process, particularly gravity and electrostatic separation, is very important in the recycling processing industry. Some characteristics of waste cable, as well as separation have a significant impact on the results and effects of aluminium recycling. At the same time, this process requires a significant amount of energy which significantly affects the overall recycling costs. This paper focuses on the recycling of waste aluminum cable by gravity and electrostatic separation. Experimental tests were performed on three different separators. Therefore, this paper presents the application of multiple criteria decision making (MCDM) methods, combining TOPSIS and AHP methods, as well as WASPAS and AHP methods, which should enable an efficient selection of the separation process. Also, the impact of the criteria weights to the ranking order of alternatives was performed in order to verify the obtained results. Results of all the studies presented in this paper show that a corona-electrostatic separation process is the most acceptable process for waste aluminium cable recycling.

Fast elimination of cable fire smoke in underground tunnels using acoustic agglomeration technology

Reduction in light transmittance and visibility due to the obscuration of fine smoke particles has been regarded as the most critical threat to fire life safety. Therefore, it is essential for smoke control in underground spaces where electric cables are installed, especially for cable tunnels, underground utility tunnels, subway tunnels, etc. This paper presents a new method of fast elimination of cable fire smoke in underground tunnels using acoustic agglomeration technology. First, the smoke production characteristics of typical electric cables are studied. It is found that the light transmittance drops to 20% after burning for about 60 s. Comparing to vertical burning, more smoke is produced when the cables are burned horizontally. Then, the elimination effect of cable fire smoke is investigated experimentally. Typically, the light transmittance is rapidly increased from 10% to 60% in 11 s, and then reaching the threshold of safe escape in fire situation in only 60 s, at an optimal frequency of 1.5 kHz and an acoustic power of 12 W. In the acoustic agglomeration process, acoustic frequency significantly influences the time required for a light transmittance to reach a given value. The elimination effect is promoted with the acoustic power until the corresponding secondary acoustic effects become significant.

High‐voltage frequency domain spectroscopy analysis of a thermally aged XLPE submarine cable under continuous and cyclic voltage based on carrier transport and polarisation characteristics

In order to ensure the safe operation of submarine cables, it is of great significance to analyse the insulation state of submarine cables from the perspectives of microstructure, carrier transport characteristics and macroscopic dielectric properties. In this study, based on the high-voltage frequency domain spectroscopy (HV-FDS) measurement system, HV-FDS experiments of fresh and thermally aged submarine cables were carried out under continuous (0.5, 2, 4 and 10 kV) and cyclic (2-10-2 kV) applied alternating voltages. Then, combining the changes of the microstructure structure of cross-linked polyethylene (XLPE) insulation, the aggregate structure deterioration model of XLPE was proposed to discuss the physical mechanism of HV-FDS characteristics of submarine cables under different voltages and insulation states. Results show that the HV-FDS characteristics of submarine cables have significant voltage dependence under continuous voltage excitation. The HV-FDS of submarine cables show memory characteristics under cyclic voltage excitation. Compared with the fresh submarine cable, the thermally aged submarine cable shows more significant voltage dependence and memory characteristics of HV-FDS. The memory characteristics of HV-FDS are mainly determined by the carriers transport and the interfacial polarisation caused by the accumulation of polar particles at the electrode/dielectric interface. This study covers the correlation mechanism among the microstructure, carrier transport and macroscopic HV-FDS properties of submarine cable insulation, which lays a foundation for further research and condition evaluation of submarine cables.

Lumped Mass Model for Flexible Cable: A Review

Model of a flexible cable plays a great role in the applications of underwater towing system, mooring line system, etc. A complete mathematical model is a basis to accurately describe the dynamic characteristics of flexible cable. This article presents a state of art comprehensive review of lumped mass model. First, the mathematical principle of the lumped mass model, including geometric simplification, force analysis, and solution, are systematically summarized.Second, the dynamic response of cable under different boundary conditions is introduced, and boundary conditions are categoried. Third, the numerical solution of the lumped mass model are assessed. Finally, based on the application of guide dog robot, the authors discussed the research future and trends. The authors aim to ealize human-robot interaction through a flexible cable.

POTDR based Power Communication Optical Cable Anti External Force Damage Monitoring System

The traditional system has low recognition accuracy for the vibration signal of optical cable damaged by external force. Therefore, a power communication optical cable anti external force monitoring system based on potdr is designed. In terms of hardware, the modular structure of the system is constructed, the potdr distributed optical fiber sensor and power supply circuit are designed, and the vibration signal of the optical cable is collected. In the aspect of software, optical fiber communication transmits vibration signal, denoises and filters the signal, extracts the state characteristics of optical cable, and monitors whether external force damage occurs. The experimental results show that, compared with the conventional system, the designed system improves the identification accuracy of the vibration signal of the optical cable damaged by external force, and ensures the operation and maintenance management level of the optical cabl.

Dynamic characteristics analysis of XLPE cable charge under different aging degree

To study the dynamic charge characteristics of XLPE cables. In this paper, a Qt test system is built in the laboratory to test the Qt dynamic charge characteristics of different thermal aging samples, and the current characteristics of different aging degrees are obtained according to the charge test differentiation. The experimental results show that the charge value of unaged sample is about 1100 nC, and the charge value of aged sample is about 2000 nC. At the moment of pressurization, the XLPE cable sheet sample flows through a large instantaneous charging current, and the initial current is more than 10−9 orders of magnitude. For the unaged sample, the charge accumulation value and conduction current value of H1 and H2 are better than those of F sample. The analysis shows that due to the insufficient aging degree of the sample, the initial aging stage is in the recrystallizaon stage.

Study on Surrounding Rock Structure Evolution Characteristics and Roof Control Techniques of the Retained Roadway Formed by Roof Cutting in Inclined Coal Seams

To control the roof during gob-side entry retaining by roof cutting in inclined coal seams, the retained gob-side roadway is zoned based on the mechanical principle and technological process of no-pillar mining with gob-entry retention. A simplified mechanical model for surrounding rocks in different subzones was established by using theoretical analysis and numerical simulation to attain the demand for the support resistance and deformation of the roof in different subzones. According to load and deformation characteristics of the roof and mechanical characteristics of NPR cables, single props, and a sliding-type gangue-retaining structure formed by U-shaped steel inserts, the supporting systems for roadways in different subzones and the constitutive model thereof were established. On this basis, the action of the supporting system was analysed and a field test was performed. The results show that the supporting system undergoes three stages of behaviour, i.e., pressure growth, yielding under constant pressure, and stabilisation during whole entry retention. It can guarantee the collaborative deformation of the supporting systems with the roof on the premise of constant support resistance, thus satisfying the requirement for roadway protection. The roadway 150 m back from the working face is stable, and the final convergence between the roof and floor of the retained entry is 257 mm, showing a favourable entry-retention effect.

Examination of design parameters affecting Nb3Sn CICC current sharing temperature using necessary condition analysis

The performance of Nb3Sn cable-in-conduit conductor (CICC) especially its current sharing temperature (T cs) is known to depend on the various parameters of the CICC such as the Nb3Sn strand characteristics, its cabling, the final geometry of the CICC cross section, the void fraction, the current distribution and other parameters. However, the performance has not been very predictable. The change in CICC T cs performance with repeated operation or electromagnetic loading is of particular concern. Furthermore, evaluation of T cs performance with respect to parametric variation of some CICC parameters has resulted in conflicting conclusions for different CICC designs. Thus, a more comprehensive review of published CICC T cs performance with respect to the corresponding CICC cable characteristics has been performed and is reported here for CICC samples whose designs and test results have been published during the past decade and more. Necessary condition analysis as well as linear regression is applied in the interpretation of the results which has found that the first stage cable twist pitch which has been the focus of much research is not that significant in determining the T cs performance but does affect T cs degradation. The direct effect of strand critical current on T cs performance was also found to be weak. On the other hand, void fraction was found to be significant in both determining T cs performance and limiting T cs degradation. Other correlations between parameters have also been studied. Overall, it seems that there has been appropriate targeting as well as overemphasis on some CICC parameters for improving Nb3Sn CICC T cs performance. No single parameter studied has been found to be a determining factor for high stable CICC T cs performance. Research on additional parameters is warranted.

Evaluation Model of Cable Insulation Life Based on Improved Fuzzy Analytic Hierarchy Process

Since the human society entered the electrification era, people’s work, life, and even the production and development of various industries in society are inseparable from the supply of electricity. The purpose of this paper is to establish a cable insulation life evaluation model based on the improved fuzzy analytic hierarchy process to test the current insulation characteristics and life of various types of cables, so as to ensure the quality of power supply and safe production of power. This paper first understands the cable insulation characteristics test process and electrical power-related knowledge through a large number of literature studies and consultation with power grid professionals. Then this paper combines the theoretical research and improvement of the fuzzy analytic hierarchy process based on the actual situation of the cable insulation characteristics, thereby constructing the cable insulation life evaluation model. In this evaluation model, this paper combines the fuzzy comprehensive evaluation method and the analytic hierarchy process as well as the actual situation of the cable characteristic test to analyze and predict the insulation life of the cable. Finally, the linear test and reliability estimation of the experimental results are carried out, and the application of this evaluation model is extended to the evaluation of insulation life of other types of cables. Based on this, this paper proposes a cable insulation life evaluation model based on the improved fuzzy analytic hierarchy process. This model combines the Weibull model and the Arrhenius model commonly used in the assessment of cable insulation aging life and the improved fuzzy analytic hierarchy process. Experiments have proved that, within a certain range, temperature factors have a significant impact on the cable insulation life. For example, when the temperature is below 55°C, the insulation life of the cable is usually 30 to 50 years. However, the evaluation model of the improved fuzzy analytic hierarchy process in this paper has much higher accuracy in evaluating cable insulation life than other life evaluation methods.

Influence of Thermal Aging on the Combustion Characteristics of Cables in Nuclear Power Plants

In this study, the combustion characteristics and emission of toxic gases of a non-class 1E cable in a nuclear power plant were investigated with respect to the aging period. A thermal accelerated aging method was applied using the Arrhenius equation with the activation energy of the cables and the aging periods of the cables set to zero, 10, 20, 30 and 40 years old by considering the lifetime of a nuclear power plant. According to ISO 5660-1 and ISO 19702, the cone calorimeter Fourier transform infrared spectroscopy test was performed to analyze the combustion characteristics and emission toxicity. In addition, scanning electron microscopy and an energy dispersive X-ray spectrometer were used to examine the change in the surface of the sheath and insulation of the cables according to the aging periods. To compare quantitative fire risks at an early period, the fire performance index (FPI) and fire growth index (FGI) are derived from the test results of the ignition time, peak heat release rate (PHRR) and time to PHRR (tPHRR). When comparing FPI and FGI, the fire risks decreased as the aging period increased, which means that early fire risks may be alleviated through the devolatilization of both the sheath and insulation of the cables. However, when comparing heat release and mass loss, which represent the fire risk at the mid and late period, fire intensity and severity increased with the aging period. The emission of toxic gases coincided with the results obtained from the heat release rate, which confirms that the toxicity of non-aged cables is higher than that of aged cables. From the results, it can be concluded that the aging period significantly affects both the combustion characteristics and toxicity of the emission gas. Therefore, cable degradation with aging should be considered when setting up reinforced safety codes and standards for cables and planning proper operation procedures for nuclear power plants.