Electrical Safety Performance Research Articles

Experimental investigation of aluminum nitride/carbon fiber‐modified composite phase change materials for battery thermal management

The phase change material is currently being regarded as an effective cooling media to be applied in the thermal management of lithium batteries-powered vehicles, in which the inorganic hydrate phase change material is desirable and widely investigated due to the high thermal conductivity, latent heat value, and low cost. However, when applied to thermal energy storage applications, supercooling and phase separation are problematic. To effectively circumvent this issue, this work considers utilizing the disodium hydrogen phosphate dodecahydrate as the matrix of the composite phase change material, as the phase transition temperature is suitable for the battery's operating temperature range. Meanwhile, the nucleating agent sodium metasilicate nonahydrate with similar lattice parameters and the thickener carboxymethyl cellulose are used to suppress the supercooling and eliminate the phase separation, respectively. Effects of nucleating agent, surface modified aluminum nitride, and short-cut carbon fiber on the supercooling degree, and thermal conductivity and curing performance in the phase change material are evaluated and discussed in detail to determine the optimal preparation scheme for Na2HPO4·12H2O/modified AlN/CF inorganic composite phase change materials. Experimental results show that the addition of 4 wt% Na2SiO3·9H2O, 4 wt% CMC, 12 wt% modified AlN, and 6 wt% CF reduces the supercooling degree of the composite phase change material to 1.9°C and increases the thermal conductivity to 1.86 W/(m·K). The composite phase change material is found to have a suitable phase change temperature (35°C), high latent heat (249 J/g), excellent shaping effect, and electrical safety performance. In addition, the composite phase change material battery module can effectively control the battery's temperature, with the maximum temperature reduced by 40.9°C at 3C discharge rate and 30°C ambient temperature compared with the natural cooling battery module. The maximum temperature difference of the composite phase change material battery module is shown to be reduced to the minimum value of 0.9°C. Highlights A novel disodium hydrogen phosphate dodecahydrate—modified aluminum nitride—carbon fiber composite phase change material is designed and prepared for battery thermal management systems. The antiwater modification scheme of AlN is proposed and assessed. The effects of AlN before and after modification on the thermal properties of CPCM are compared. The joint use of nucleating agent sodium metasilicate nonahydrate and thermal conductive filler AlN contributes to significantly inhibiting the supercooling of hydrate salt. The addition of CF can effectively increase the thermal conductivity of CPCM and prevent its leakage. CPCM has suitable phase change temperature, high thermal conductivity and latent heat value, excellent electrical safety, and stable curing performance. The battery test bench is constructed and the discharge test of the CPCM battery module is carried out. The results show that the CPCM battery module has excellent cooling performance and temperature uniformity.

Analysis of the Parameters that Affect Electrocution Accidents in Small-scale Industrial Workshops Based on their Electrical Safety Performance

Analysis of the Parameters that Affect Electrocution Accidents in Small-scale Industrial Workshops Based on their Electrical Safety Performance

The MCCB Electrical Clearance and Creepage Distance Measurement Uncertainty Evaluation

The electrical clearance and creepage distance are two key parameters for the design of MCCB (molded case circuit breaker, MCCB), which directly influences the electrical safety performance of MCCB. In this paper, the electrical clearance and creepage distance measurement uncertainty were evaluated through the uncertainty sources analysis, the mathematical model establishment and the components uncertainty calculation, to ensure the accuracy of the measurement results.

Common Problem Analysis in Electromechanical Equipments of Highway External Field

Electromechanical system is the main auxiliary system for expressway traffic facilities and the main tool to implement modern management. In this paper electrical safety performance and environmental adaptation performance were introduced first. Then highway external field electromechanical equipments were recommended. This may give some references to electrical and mechanical equipment design, production and construction.

Model of current threshold for perception in testing electrical safety performance

A generalized mathematical model of human body current threshold for perception was established and the current flowing through human body could be arbitrary cyclical waveforms. The relationship between human body current threshold for perception and current frequency, true root mean square (RMS) value and influence factor was described. A test system was established based on electroencephalogram (EEG) to study the relationship between human body current threshold for perception and current waveform, frequency and duty cycle so that the data could be obtained objectively and reliably. At least 850 groups of current threshold for perception and 16-lead EEGs were acquired. The theoretical analysis are verified by experimental data, and an amendment proposal on leakage current evaluation limits specified in International Electro-Technical Commission (IEC) standards is suggested.

Training and qualifying your employees

Procedures alone cannot provide an improvement in electrical safety performance. Personnel who are exposed to electrical hazards must understand the basics of electrical hazards and safe work practices in order to implement the procedures. Training and qualifying your employees on these issues can be difficult and confusing. This article outlines a process for training employees on electrical safety issues. It will define qualified in terms that will satisfy the requirements of the Occupational Safety and Health Administration (OSHA) and NFPA 70E of the National Fire Protection Agency (NFPA) and also define the steps to meet the requirements of being qualified. The information contained in this article is the result of training the author has performed with electricians and nonelectrical personnel. The information is based upon the interpretation of the author. Employers should review the information and compare it to their interpretation of the regulations.

Refocusing Electrical Safety

Electrical safety needs to be refocused. Over the last few years, there has been tremendous attention given to the arc flash hazard phenomenon. Even though this hazard needs attention to reduce the number of injuries occurring because of it, in some ways, it has become the predominate focus of electrical safety. Electrical safety is more than just the arc flash hazard. Electrical safety needs to be a holistic approach that includes all aspects of electrical safety. The Electrical Safety Program, which proved to be a good tool, is defined in NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces. However, even this falls short of what is needed to make a step change in electrical safety performance. This paper will attempt to identify the voids in electrical safety and focus attention on the items that need to be addressed to take a more holistic approach to electrical safety

Maintaining safe electrical work practices in a competitive environment

Worldwide competitive pressures have forced engineering and construction organizations to face increased workloads using fewer experienced personnel. Significant organizational and individual effort is required to maintain high standards of electrical safety in this climate. In addition, there is recent increased recognition of hazards from electrical high-energy sources. The efforts of one corporation to maintain electrical safety performance are described. Basic electrical hazards are reviewed, and a flowchart method of categorizing hazardous electrical tasks is presented. A matrix is provided to select appropriate personal protective equipment and identify procedural requirements.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>