As the application of terminal products in wiring becomes more frequent, an increasing number of users are placing higher demands on them. Consequently, significant changes have been made to the structure and wiring methods of terminals. The initial single structure has evolved into a variety of wiring structures, categorized for different wiring environments, making our use more convenient. Additionally, the structure of wiring terminals has become more user-friendly, significantly improving wiring speed and reducing the labor intensity for workers.
Insulating connections for low-voltage equipment have stringent requirements from design to material selection. This article aims to briefly analyze the use and planning requirements of terminal connectors in low-voltage electrical equipment, focusing on the principles of insulation cooperation and the specific requirements of low-voltage equipment for insulation.
Insulation collaboration refers to selecting electrical insulation properties based on product application requirements and surrounding environments. The ultimate goal of product insulation collaboration can only be achieved by assessing the intensity of various effects (such as voltage and other factors) it withstands throughout its lifespan.
Considerations for the working environment of low-voltage equipment, factors influencing insulation cooperation generally include:
Additional voltage related to equipment; extra insulation voltage; extra impulse voltage determined by overvoltage during the operation of the equipment. Additionally, environmental conditions such as: temperature, humidity, solar radiation, heating, ventilation, dust, moisture, etc.; other factors like: pollution, dielectric function (creepage current trace index CTI), voltage effect duration, frequency, altitude (atmospheric pressure), electric field conditions, uniform electric field; non-uniform electric field.
Analysis of Insulation Damage and Its Influencing Factors
One is dielectric breakdown (thermal breakdown), where under the effect of a strong electric field, the dielectric material heats up due to dielectric loss. If the heat cannot dissipate in time, the temperature continues to rise, causing low molecular volatile substances to escape and damage the molecular structure of the material, ultimately leading to dielectric breakdown.
The second is insulation aging, which refers to the irreversible physical and chemical changes of insulation materials under various elements during equipment operation, leading to a sharp decline in the electrical and mechanical properties of the materials, causing damage known as insulation aging.
Therefore, when the insulation planning of terminal connections with electrical air gaps does not meet the requirements, the method of creepage distance should be employed, which involves adding solid insulation between the conductive bodies for isolation.
Due to defects in solid insulation materials (such as impurities and air gaps), even though the voltage is far below the breakdown level, it can still be damaged by local discharges, thereby reducing its lifespan. The damage to solid insulation materials accumulates over time, as the process is not fully recoverable and can eventually lead to breakdown or aging, resulting in loss of efficiency. Under high-frequency voltage effects, the increased material loss and local discharges can further decrease the service life.
