How to accurately evaluate the relationship between the thickness of the insulation layer and the electrical performance of mineral insulated cables?

1. Understand the factors affecting the thickness of the insulation layer
Working voltage: The thickness of the insulation layer of mineral insulated cables is determined according to their working voltage. Higher working voltages require thicker insulation layers to ensure electrical safety.
Electric field strength tolerance: The main function of the insulation layer is to withstand the electric field strength inside the cable. Therefore, the thickness of the insulation layer needs to be sufficient to resist the maximum electric field strength that may be generated to prevent the occurrence of breakdown.
Insulation material properties: The electrical properties, mechanical properties, and heat resistance of the insulation material will affect the selection of the thickness of the insulation layer. For example, some high-performance insulation materials may allow the use of thinner insulation layers while maintaining the same electrical performance.
2. Key indicators for evaluating electrical performance
Insulation resistance: Insulation resistance is an important indicator for measuring the ability of the cable insulation layer to isolate current. Thicker insulation layers usually have higher insulation resistance values, which helps reduce the risk of current leakage and short circuits.
Withstand voltage: Withstand voltage refers to the ability of the cable to maintain stable electrical performance under a certain voltage. Thicker insulation layers can provide higher withstand voltage levels to ensure that the cable can still work normally under high voltage environments.
Thermal stability: Mineral insulated cables generate heat during operation, and the insulation layer needs to have good thermal stability to prevent performance degradation or damage caused by overheating.
3. Evaluation method
Theoretical calculation: According to the working voltage of the cable, the electric field strength bearing capacity, and the performance parameters of the insulation material, the reasonable range of the insulation layer thickness is obtained through theoretical calculation.
Experimental verification: The relationship between the insulation layer thickness and the electrical performance is verified through laboratory tests or field tests. This includes conducting withstand voltage tests, insulation resistance tests, and thermal stability tests to evaluate the actual performance of the cable.
Comparative analysis: Compare and analyze cables with different insulation layer thicknesses to observe the differences in their electrical properties. This helps to more intuitively understand the impact of insulation layer thickness on electrical performance.
4. Precautions
Compliance with standards: During the evaluation process, it should be ensured that the insulation layer thickness of the cable meets the relevant national and industry standards. Cables that do not meet the standards may pose safety hazards and should not be used.
Comprehensive consideration: The selection of insulation layer thickness should take into account multiple factors, including working voltage, electric field strength, insulation material performance, and cable laying conditions. Too thick or too thin insulation layers may have an adverse effect on electrical performance.
Practical application: During the evaluation process, the actual application scenarios and requirements of the cable should also be considered. For example, cables used in harsh environments such as moisture and corrosion may require thicker insulation to improve electrical performance and durability.