Method for assessing the state and residual life of the insulation based on analysis of the time of discharge of the capacity of electric cables

As of today, the problem of the lack of non-destructive methods for assessing the state and determining the residual life of the insulation of electrical cables is relevant for cable lines in operation, and especially for lines that have exhausted their service life. The research presented in the framework of this article is aimed at creating a non-destructive technique for assessing the state and residual life of electrical cables insulation. The study was carried out using computer simulation methods and using the basic theoretical laws of physics and electrical engineering. A method for assessing the condition and residual life of electrical cable insulation has been developed, which is based on the analysis of the discharge time of the cable capacity. The applicability of the method is determined, instructions are given on its applicability and the analysis of the output data. The obtained results can be used by power grid companies and industrial enterprises to analyze the state of the insulation of electrical cables.

The use of optical fiber for the creation of security systems for electrical cables of distribution networks of 0.4 kV

The article presents the results of research aimed at solving important production issues related to the theft of power cables and reducing the reliability of electrical networks with a voltage of 0.4 kV. To implement the security system, a single-mode optical fiber and a hardware and software complex for data processing were used. The results of the work can be used in security systems for various purposes, including telecommunications and construction systems. During the experiments, it was found that the photoelasticity effect occurs during mechanical action on the optical fiber, which causes changes in the refractive indices of the shell and core, while the properties of light change. In contrast to the known security systems and methods of fixing violations, a high-resolution television matrix is used, and not a photodetector device that records only changes in intensity. The television matrix is installed at the output of the optical fiber and records all changes in the light spot, and the hardware and software complex converts these changes into numerical values.

IMPACT OF THE ELECTRIC CABLES INSTALLATION ON THE IGNITION PARAMETERS OF THE SPRUCE WOOD SURFACE

This study is aimed to investigate of an impact of electrical cables installed on Norway spruce (Picea abies(L.) Karst.) wood board surface on main ignition parameters (mainly critical heat flux, ignition temperature, thermal response parameter and thermal inertia). Ignition parameters have been determined by dependence of ignition times (raised to the power of -1, -1/2 and -0.547) on heat flux. Initiation times have been measured for three configurations of spruce wood boards with surface dimensions of 100 x 100 mm ± 1 mm (the first configuration: board without cables on surface, the second configuration: board with three electrical cables on surface -spacing between cables was equal to their diameter and the third configuration: board with five electrical cables -spacing between cables was equal to their diameter) at five heat fluxes (30, 35, 40, 45 and 50 kW·m-2). Obtained results proved that installation of the electrical cables on the spruce wood board surface has a significant impact on the ignition parameters. The critical heat flux (8.5 kW·m-2), apparent thermal inertia0.20 ± 0.02 kJ2·m-4·K-2·s-1and ignition temperature 324 ± 105°C of spruce wood board increased up to 18 ± 3 kW·m-2(critical heat flux), 0.68 ± 0.03 kJ2·m-4·K-2·s-1(apparent thermal inertia) and 475 ± 27°C (ignition temperature) by theinstallation of electrical cableson the surface of spruce wood board.

Electro mechanical properties changes of LDPE doped with industrial type MgO for cable insulation purposes

<p>This manuscript introduces the changes of a comprehensive electromechanical properties bundle for low density polyethylene compounded to microscale magnesia (LDPE/MgO) to obtain electrical cables insulating material. Composites of various filler loading weight ratios were prepared by melt intercalation technique; multiple samples were produced in sets as they were cut with definite dimensions as per recommendations of the related testing standard then electrically and mechanically examined following the instruction dictated by the code while preserving typical test condition for all sets. Dielectric strength, volume resistivity, capacitance, and loss angle were the tests of the electrical test pack, while elongation, tensile strength, and melt flow rate were the mechanical and rheological tests applied. Test’s findings were compared to each other’s and to the base material to identify the differentiation. Electrical test results show improvements in the composite features at low loading percentages, whereas the mechanical tests revealed a deterioration in the mechanical properties along with all ratios under investigation. The research aims to determine the compositing benefit extents and drawbacks when a conventional compounding method and inexpensive filler are used, incurring marginal cost impact.</p>

Fire Risk Situation Analysis in the Nimtoli Area of Old Dhaka

Assessment of the fire risk situation of Nimtali area by using eight indicators related to the fire source, fire spreading and evacuation during fire incidents was conducted. The results revealed that none of the buildings has emergency exits, fire protection measures, fire hydrant and provision of a fire drill. The area is densely populated. Most of the buildings are mixed-used and have no space in between. Electrical cables are haphazardly hanging from poles. Access roads are incredibly narrow. By analyzing eight indicators, it is found that the entire Nimtoli area is still at risk of fire hazard. Within Nimtoli, 32% area is at high risk, and 45% is at moderate risk of fire hazard. Proper fire safety measures and safety inspection, regular maintenance of utility lines, awareness about fire hazards among the dwellers, proper implementation of Bangladesh national building code (BNBC) and regulation of mixed-use of buildings can drastically reduce the fire risk in the urban area of Bangladesh. J. Asiat. Soc. Bangladesh, Sci. 46(1): 91-102, June 2020

Fibre Spring Mooring Solution for Mooring Floating Offshore Wind Turbines in Shallow Water

Mooring of Floating Offshore Wind Turbines (FOWT) in shallow water sites (30–80m) is challenging. These sites account for a significant proportion of the nearer to shore potential wind farm locations, and are desirable as they are closer to existing infrastructure and easier to access. Mooring large floating structures in very shallow waters however results in very long heavy mooring lines designed to minimize platform surge and protect the electrical cables. This paper presents an innovative Fibre Spring Mooring (FSM) solution which combines a high modulus, non-stretch, lightweight rope with a compliant nonlinear polymer spring offering a complete semi-taut mooring system which can be connected directly between the platform and the seabed. The paper will present Orcaflex simulation results of a 12MW barge type FOWT platform, moored using a semi-taut FSM mooring at three chosen North Sea locations close to existing wind farms, of 30m, 40m and 50m water depths. Different FSM configurations, with different line lengths, footprint, and ratio of fibre to spring are considered.

Fire Growth Rate Index as a Key Fire Characteristic of Electrical Cables

This study deals with the Fire Growth Rate Index (FIGRA) as a key fire characteristic of electrical cables (determined by a cone calorimeter) that allows to estimate their reaction to fire class. Three power (supply) electrical cables (reaction to fire class B2ca) were tested by a cone calorimeter using different heat fluxes of 20, 30, 40 a 50 kW·m−2. The cables were three-wire (cross-section of each wire was 1.5 mm2) with a nominal voltage of 0.6 kV (alternating current), resp. 1 kV (direct current). The cable sheaths were made of an ethylene copolymer filled with aluminum hydroxide. The beddings were made of an ethylene copolymer filled with a mixture of aluminum hydroxide and calcium carbonate. The conductor insulations of one electrical cable were made of crosslinked polyethylene and the conductor insulations of the other two electrical cables were made of an ethylene copolymer filled with aluminum hydroxide. FIGRA was determined per unit length and unit area of electrical cables. FIGRA increased with increasing heat flux. At a heat flux of 50 kW·m−2, all the electric cables examined showed a very similar FIGRA (from 0.19 to 0.21 kW·m−1·s−1 and 18.4 to 21.2 kW·m−1·s−1, respectively). Conversely, at a heat flux of 20 kW·m−2, the investigated cables showed greater FIGRA variance (in the range of 0.11 to 0.16 kW·m−1·s−1 or 10.8 to 16.2 kW·m−1·s−1).

A Survey of Electrical Materials Counterfeiting in Bayelsa State: A Case Study of Yenagoa Local Government Area

Electrical cables are the bedrock of every electrical wiring and installation. In this study, some essential cable properties (size, electrical resistivity and flame retardant) of electrical cables sold in Bayelsa state were determined according to NIS-approved methods. Four commonly used electrical cables (1 mm2, 1.5 mm2, 2.5 mm2, and 4 mm2) in Bayelsa State were sampled. Results obtained showed that most of the electrical cables sold within the Yenagoa metropolis fell below International Standards. Only 58% of the 1 mm2, 43% of the 1.5 mm2, 62% of the 2.5 mm2 and 46% of the 4 mm2 cables met the NIS recommended sizes. For electrical resistivity, most of the cables failed to meet the NIS recommendations. The resistivity of 45% of the 1 mm2 sampled cable, 39% of 1.5 mm2, 52% of the 2.5 mm2 and 33% of the 4 mm2 sampled cable were above the maximum limits approved by the Nigeria Industrial Standard. High resistivity observed in these cables can lead to electrical fire due to temperature buildup within the cable. Most of the cable insulators were made from good fire retarding materials. 92% of the 1 mm2, 93% of the 1.5 mm2, 89% of the 2.5 mm2 and 87% of the 4 mm2 cable insulators had flame retarding characteristics. Results from this study can be used as a guide by standard regulatory agencies to monitor the sales of electrical cables in the state since most of the cables sampled in this study fell below National and International standards. Keywords: Electrical cables, electrical fire, electrical resistivity, fire retardant, standards

Methods of Temperature Monitoring in Low Voltage Electrical Cables using Composite Materials

The article presents the most important methods and technologies used to monitor the temperature of low voltage power supply cables, which supply 400V in three-phase mode, trying to highlight the method of using composite materials, materials that are included in the material constructive of the cables, these having the role of temperature sensor. Temperature monitoring is performed along the electrical cables, to transmit in real time information on the evolution of temperatures along the entire length of the cable, at any point, during their entire life. The article will focus on the method of inserting optical fibres inside the power supply cables, which will be used as a temperature measuring instrument. Using the Reman effect, a method of reflecting the injected light at one end of the optical fibre, by processing the received signals, the evolution of the temperature inside the electric cable can be detected with great precision, over long distances and with great accuracy. the evolution of the temperature inside the electric.