Cable Tray Research Articles

Experimental Study on Friction Seismic Sway Bracings for Seismic Protection of Building Nonstructural Components

ABSTRACT This study investigates seismic performance of a dry friction damper called Seismic Sway Bracing (SSB) used for seismic protection of nonstructural components (NSCs) such as mechanical and electrical lifeline systems in a building. Low- and high-performance type (L- and H-type) SSBs were experimentally tested from material-to-member-to-structure (or system) level. Firstly, six standard coupon tests of Q235 and SGC340 steel specimens were conducted. Then, tensile tests of 24 friction components of the damper (L- and H-components) were conducted. Finally, quasi-static tests of 20 specimens were conducted by installing single and double assemblies of friction dampers on the prefabricated rigid moment-resisting frame structure. Double assemblies of dampers were bridged by a pipe or a cable tray to accommodate additional weight. The damper’s key influencing factors such as preloaded bolt’s torque, ultimate bearing capacity, material validity, and fragility functions are investigated. Afterward, the best parameters for their optimum seismic performance are recommended. The result shows that these dry friction dampers are practical and reliable equipment to protect an NSC of a building from a horizontal swaying of an earthquake.

Electromagnetic interference caused by an electric-line current in a cable tray in nuclear power plants

This paper presents a mode-matching analysis of the electromagnetic coupling between open cable trays in an indoor structure when an electric-line current is generated as an electromagnetic source. We validated the mode-matching method by comparing the mode-matching results with those computed from a commercial electromagnetic simulator and then investigated the strength of the electric-field coupled in a victim cable tray while varying the distances between cable trays and architectural surfaces. The results of this study provide geometrical information on the placement of open cable trays to avoid electromagnetic interference problems.

On the Relation between Strength and Stiffness of Cable Tray

In order to realize the optimal design of the cable supporting system for the purpose of material saving and energy saving and green manufacturing, the strength-stiffness ratio is proposed in the paper in nondimensional form, which defines quantitatively the relation between the static load strength and stiffness of the cable tray. On the premise of ensuring service safety, the correlation between the strength and stiffness of the cable tray under static load is discussed extensively through the theoretical analysis of the mechanical model. The weakest link in the carrying capacity of the cable tray as well as the issue that needs to pay attention is proposed in the process of design and the test of the cable tray. A reasonable strength-stiffness ratio will help to make full use of the potential of material strengths. The value of the strength-stiffness ratio is obtainable by means of the finite element method or by the loading test of the cable tray. It is shown through the analysis that the value of the strength-stiffness ratio being setting in the range close to but less than 1 will make comparatively reasonable material utilization and will help the deflection test going smoothly to obtain a relatively safer allowable working load for the cable tray.

Improved model for estimating sidewall effect on the fire heat release rate of horizontal cable tray

The occurrence rate of fire events involved with cables is high and a fire hazard analysis is needed. A cable tray may be commonly placed on a wall. The fire hazards of multiple cable trays are affected by the supporting wall to give a higher maximum heat release rate. Taking the wall constraint effect on cable burning into account, a new model for the fire heat release rate of a cable tray fire against a sidewall is developed based on small scale (cone calorimeter) measurements. The newly developed model introduces a constant m to reflect the acceleration in cable burning due to the sidewall. With a properly chosen value of m, the results obtained using the newly developed model agree well with the experimental data. The error in the peak fire heat release rate value is considerably smaller than those of other models. This work improves the understanding of the fire risk of a cable tray with a sidewall.

Experimental Study on Delaying the Failure Time of In-Service Cables in Trays by Using Fire-Retardant Coatings

Improving the fire resistance of the key cables connected to firefighting and safety equipment is of great importance. Based on the engineering practice of an oil storage company, this study proposes a modification scheme that entails spraying fire-retardant coatings on the outer surface of a cable tray to delay the failure times of the cables in the tray. To verify the effect, 12 specimens were processed using five kinds of fire-retardant coatings and two kinds of fire-resistant cotton to coat the cable tray. The specimens were installed in the vertical fire resistance test furnace. For the ISO 834 standard fire condition, a fire resistance test was carried out on the specimens. The data for the surface temperature and the insulation resistance of the cables in trays were collected, and the fireproof effect was analyzed. The results showed that compared with the control group, the failure time of the cable could be delayed by 1.57–14.86 times, and the thicker the fire-retardant coatings were, the better the fireproof effect was. In general, the fire protection effect of the fire-retardant coating was better than that of the fire-resistant cotton.

Computer-aided 3D routing of Instrumentation Cables

This paper presents the process of 3D routing of Instrumentation cables for a thermal power plant using the integration capabilities of Instrumentation, Electrical and 3D modules of SmartPlant[1]. Efficient use of integration linkages amongst various modules of SmartPlant is explained. Workflow of preparing cable schedule for Instrumentation cables in an integrated environment is discussed. The processes of routing the Instrumentation cables in an existing 2D CAD software and in 3D software are compared and rules and constraints applied on cable tray network in 3D module for routing the Instrumentation cables are presented. The output of 3D software based routing of Instrumentation cables is compared with the output of 2D software based routing of Instrumentation cables and presented. Finally, the issues faced during the complete process and their resolutions with learning are discussed.

Experimental study at reduced-scale of fire spread between electrical cabinets located opposite each other

The ability of an electrical cabinet fire to spread to neighbouring cabinets is a major concern for fire safety in nuclear power plants. Twelve intermediate-scale fire tests were performed to determine the fire spread conditions (FSCs) from a burning enclosure (BE) to an opposite enclosure (OE) equipped with either a non-combustible (glazed or metallic) or a combustible (poly(methyl methacrylate), PMMA) front panel. The effects on the FSCs of the separation distance (SD) between the enclosures, the target type (electrical component) contained in the OE and overhead electric cable trays were also investigated. Fire spread to the OE equipped with a glazed panel when the total transmitted heat flux led to the spontaneous ignition of the target. This outcome was not obtained for the metallic panel. For the PMMA panel, fire spread when flames coming from the BE reached the flammable gas mixture produced by the panel. For both glazed and PMMA panels, the FSCs were obtained for higher SDs when overhead electric cable trays were used. The tests also revealed that the faster and more powerful PMMA panel fire was not obtained for the minimum SD studied. Finally, total transmittances of the glazed and PMMA panels were assessed.

A New Industrial Cable System Parameter Calculation Methodology Based on 3-D Finite Element Analysis

High-frequency phenomena require appropriate models to be accurately reproduced and analyzed by means of computational simulations. Within industrial facilities, insulated cables are widespread and their modeling in a broad range of frequencies is complex due to the proximity between these and particular issues concerning the installation methods. In this context, in this article, the authors improve a methodology presented previously to make it suitable for the most used installation methods in industry, namely the perforated and the ladder-type cable trays, not addressed so far. The required modifications regarding the methodology reformulation are explained and the obtained results are presented and compared to those derived from the previously available technique, followed by discussions and physical insights.

Study of Hillock and Zinc Whisker Evolution in Five Different Cable Tray Coatings

The main objective of this work is the study of the hillock and zinc whisker evolution of five different commercial zinc coatings applied on the same base steel wires of the patented EASYCONNECT system cable trays manufactured by VALDINOX Ltd.: white zinc alkaline electrolyte, yellow zinc trivalent electrolyte, acid zinc electrolyte, hot dip galvanized, and zinc nickel coating. The limited literature on the subject is summarized, and then the coating thickness, chemical composition, hardness and surface rugosity are characterized. The hillock and whisker density evolution are evaluated over a period of 12 months, considering the presence of compression bending stresses. It is concluded that the white alkaline and yellow trivalent coatings are the most affected, while the zinc-nickel shows the best behavior with no presence of whiskers; the acid zinc electrolyte also shows good results despite the delayed appearance of whiskers from the ninth month; the hot-dip galvanized coating does not show any presence of zinc whiskers or hillocks.

An In-depth Analysis for Optimal Cable Tray Support Span

Nowadays, it is crucial to reduce the cost of the overall project so that the competitiveness of offshore oil and gas without compromising on quality or safety can be achieved. This study investigates how to define the longest cable tray support span considering constructability in order to reduce the number of supports which is a chief cost of a cable tray system. This study presents not only material and geometry frequently used for cable tray but also the formula to estimate the maximum cable load which can be installed within cable tray. To verify the longest span without increasing the crosssection of cable tray, finite element modelling approach was employed based on ANSYS and comparisons were made between numerical analysis and simplified hand calculation. The constructability for the longer span obtained from finite element analysis has been validated in view of manual handling of the cable tray. It is shown that the optimal span suggested in this paper can lead to a better economic benefit without degrading the constructability. For instance, as the span is longer, the cost of material as well as construction manpower can be saved. It is also expected that this approach will contribute to enhance the competitiveness of offshore oil and gas.

Performance-based earthquake engineering methodology for seismic analysis of nuclear cable tray system

The Pacific Earthquake Engineering Research (PEER) Center has been developing a performance-based earthquake engineering (PBEE) methodology, which is based on explicit determination of performance, e.g., monetary losses, in a probabilistic manner where uncertainties in earthquake ground motion, structural response, damage estimation, and losses are explicitly considered. To carry out the PEER PBEE procedure for a component of the nuclear power plant (NPP) such as the cable tray system, hazard curve and spectra were defined for two hazard levels of the ground motions, namely, operation basis earthquake, and safe shutdown earthquake. Accordingly, two sets of spectral compatible ground motions were selected for dynamic analysis of the cable tray system. In general, the PBEE analysis of the cable tray in NPP was introduced where the resulting floor motions from the time history analysis (THA) of the NPP structure should be used as the input motion to the cable tray. However, for simplicity, a finite element model of the cable tray was developed for THA under the effect of the selected ground motions. Based on the structural analysis results, fragility curves were generated in terms of specific engineering demand parameters. Loss analysis was performed considering monetary losses corresponding to the predefined damage states. Then, overall losses were evaluated for different damage groups using the PEER PBEE methodology.

Numerical Fire Spread Simulation Based on Material Pyrolysis—An Application to the CHRISTIFIRE Phase 1 Horizontal Cable Tray Tests

A general procedure is described to generate material parameter sets to simulate fire propagation in horizontal cable tray installations. Cone Calorimeter test data are processed in an inverse modelling approach. Here, parameter sets are generated procedurally and serve as input for simulations conducted with the Fire Dynamics Simulator (FDS). The simulation responses are compared with the experimental data and ranked based on their fitness. The best fitness was found for a test condition of 50 kW/m2. Low flux conditions 25 kW/m2 and less exhibited difficulties to be accurately simulated. As a validation step, the best parameter sets are then utilised to simulate fire propagation within a horizontal cable tray installation and are compared with experimental data. It is important to note, the inverse modelling process is focused on the Cone Calorimeter and not aware of the actual validation step. Despite this handicap, the general features in the fire development can be reproduced, however not exact. The fire in the tray simulation extinguishes earlier and the total energy release is slightly higher when compared to the experiment. The responses of the material parameter sets are briefly compared with a selection of state of the art procedures.

IDENTIFICATION OF WORK ACCIDENT RISK OF TRAY CABLE INSTALLATION IN X APARTMENT PROJECT

Work accidents that occured in Indonesia, 32% are accidents from the construction sector. The construction sector is a sector with a work environment where there were so many hazard risks. Cable tray installation is one of the jobs in a construction project. The purpose of this research is to get an overview of the steps in the installation of cable tray and the its risk. The process of identifying work accident risk in this study uses Job Safety Analysis (JSA). Falling from height is one of the workplace accidents in the cable tray installation process. Risk control is needed to prevent work accidents that can occur due to cable tray installation.

Experimental investigation on maximum ceiling jet temperature generated by a vertically spreading cable fire

Maximum ceiling jet temperature (MCJT) is an important parameter for evaluating fire risk. An important characteristic of vertical cable tray fire is the upward spreading of the cable flame along the cable tray, which leads to a decrease in the distance between the fire source and compartment ceiling during such a fire. Thus, full-scale fire experiments using vertical cable trays were conducted in a confined compartment to investigate the MCJT. The upward spreading of the cable flame leads to transition of the MCJT dominated by the plume region to intermittent region of the flame. In particular, it is observed that the MCJT suddenly increases from ~200 °C to more than 600 °C at this transition point. Taking the upward spreading cable flame along the vertical cable tray as a point fire source moving with constant velocity, a modified model is proposed to estimate the MCJT. Prediction using the proposed modified model yields promising results. The local prediction error for the modified model is less than 12%, and the global prediction error is between 23.6% and 38.6%. These errors are significantly lower than those for other models that assume a fixed fire source.

Study and Characterization of the Dielectric Behavior of Low Linear Density Polyethylene Composites Mixed with Ground Tire Rubber Particles.

The waste rubber vulcanizate, on account of its stable, cross-linked and three-dimensional structural arrangement, is difficult to biodegrade. Thus, the ever-increasing bulk of worn-out tires is a serious environmental issue and its safe disposal is still a challenging task reported widely by the scientific community. The rubber materials, once they end their useful life, may present difficulties to be reused or recycled. At present, only one tire recycling method is used, which involves grinding and separating steel and fibers from vulcanized rubber, and then using rubber for industrial applications, such as flooring, insulation, footwear. In this paper, a new compound material is presented from a base of reused tire powder (Ground Tire Rubber: GTR) as a mixer and linear low-density polyethylene (LLDPE) as a matrix. The reused tire powder, resulting from grinding industrial processes, is separated by sieving into just one category of particle size (<200 μm) and mixed with the LLDPE in different amounts (0%, 5%, 10%, 20%, 40%, 50% and 70% GTR). Due to the good electrical properties of the LLDPE, this study’s focus is settled on the electrical behavior of the obtained composites. The test of the dielectric behavior is carried out by means of DEA test (Dynamic Electric Analysis), undertaken at a range of temperatures varying from 30 to 120 °C, and with a range of frequencies from 1 to 102, to 3·106 Hz, from which permittivity, conductivity, dielectric constant and electric modulus have been obtained. From these experimental results and their analysis, it can be drawn that the additions of different quantities of GTR to LLDPE could be used as industrial applications, such as universal electrical cable joint, filler for electrical applications or cable tray systems and cable ladder system.

Analysis of Electromagnetic Interference Between Open Cable Trays

This paper presents an analytical interpretation of electromagnetic interference between solid-bottom type open cable trays in a nuclear power plant under the assumption that an electric-line current is undesirably generated from a damaged cable in an open cable tray. Based on the superposition principle and Helmholtz's equation in conjunction with the separation of variables, we employ a mode-matching method to obtain analytical solutions to the postulated electromagnetic interference problem. Before conducting a mode-matching analysis, we investigate the radiating principle of the electric field interfering with a victim cable tray by deriving the array factor in consideration of an imaginary electric-line current. In addition, we characterize the electric fields with a propagating mode at an observation point in the victim cable tray using the derived expression of the electric field. Based on this, we validate the formulation and computation of our mode-matching method and then computationally investigate the strength and distribution of interfering electric fields in terms of the separation distances provided in regulatory guidance on the electrical independence of a nuclear power plant. Finally, we compute the strength and distribution of the interfering electric field at the observation point when the location of an electric-line current is modified. The results of the study provide us with the useful information to alleviate the electromagnetic interference between open cable trays in a nuclear power plant.

3D Scanning as a part of “Virtual Plant Asset Management” – a short trip to industry 4.0

Today 3D Scanning of existing assets is a well-known tool to generate a reliable foundation for an engineering project. With 3D scans exact dimensions and positions of existing equipment, piping, cable trays and others can be measured and the data can be read as interfering edges when modelling new equipment with a 3D tool. However, the data generated during scanning can provide a much more extensive benefit for the operation of a plant, if prepared in an appropriate way. With an intelligent link of the scanned data with the information of Virtual Plant Asset Management, an all-embracing virtual plant can be generated. Within such a virtual plant, the for various purposes required information can be consolidated from different tools for engineering, operation, maintenance, etc. and be displayed instantly and vividly for the operator. As a result this ensures the on-time availability of any information to take decisions everywhere in an existing plant and thus shortens the time for decisions etc. Integrating 3D scan data into a Virtual Plant Asset Management requires only two main steps and the required infrastructure is well known and easily available on the market without high effort.

Analysis of Problems of and Measures Against Fires Originating from Ceilings

Five or six catastrophic fires occur in Korea each year. When catastrophic fires originate from a ceiling, they commonly result in many casualties. This study focused on six catastrophic fire cases that originated from the ceiling, which resulted in many casualties, and analyzed their characteristics and problems. According to this analysis, five measures were proposed. 1) When fires originate from a ceiling, an indoor hydrant should be used instead of an extinguisher. 2) The spread of fire and smoke to the upper floors should be blocked against vertical penetration using fireproof charging. 3) The use of combustible materials above the ceiling must be avoided. 4) Synthetic resin conduits, connections, and cable trays must be replaced with metal conduits, connections, and cable ducts to prevent fires caused by electrical factors. 5) Fire detectors must be installed if combustible materials are present in the space above the ceiling. Keywords: Ceiling Fire, Catastrophic Fire, Fire Case Analysis, Fire Investigation

케이블의 배열형태에 따른 화재 위험성에 관한 연구

In this study, the thermal and flame propagation characteristics of cable in perforated cable tray used in a low voltage indoor distribution line were analyzed according to the arrangement of the cable using Light PVC sheathed circular cord(VCTF) cable. A thermocouple was attached to the inside and outside of the cable to measure the temperature. The cables were arranged in vertical and horizontal directions and, layered in triangular and rectangular shapes. As compared to the temperature inside a single cable, the temperatures increased when numerous cable were arranged in a horizontal direction and layered in triangular and rectangular shapes. The temperature inside the cables reached a peak of 305 ℃ when the current was twice the allowable current. At allowable current, the temperature increased to 62℃ when the cables were layered in a rectangular shape. This was close to the maximum permissible temperature for VCTF cable(i.e., 70 ℃). The insulation resistance of the VCTF cable declined dramatically in accordance with increases in temperature, which not only raised the risk of short circuit and ground faults but also accelerated the cable deterioration. The flame propagated at a velocity of 2.7 ㎝/sec in the vertical direction and 0.95 ㎝/sec in the horizontal direction at twice the allowable current. The faster propagation velocity in the vertical direction was due to the characteristics of flame and plume, which moved in an upward direction due to a buoyancy effect.

Fire development in multi‐compartment facilities: PRISME 2 project

Fire development in multi‐compartment facilities: PRISME 2 project