A method and device for calculating the ampacity of a cable when there is water in a power pipe

Abstract

The present invention provides a method and device for calculating the current carrying capacity of a cable when there is water in the power pipe, comprising the following steps: obtaining various parameters according to the model of the cable and the model of the cable pipe; obtaining the height h of the water in the cable pipe, based on The height h, the outer diameter D in the parameters e , inner diameter D d and the air layer thermal resistance T 41 Calculate the thermal resistance T of the accumulated water in the drain pipe 41water The thermal resistance T of the air layer in the pipe 41air ;Judge whether the height h is greater than the outer diameter D e ;According to the judgment results, use different calculation methods to calculate the ratio μ of the heat dissipation from the outer skin to the water relative to the total loss of the cable 1 , The ratio of the heat dissipation in the air to the total loss of the cable μ 2 and the contact area S between accumulated water and air in the pipe per unit length w ; Based on S w Calculate the heat W that the accumulated water in the drain pipe dissipates to the air layer in the pipe wa ; Use the heat W wa With the above parameters, the current carrying capacity I of the cable when there is water in the drain pipe is calculated.

Description

technical field [0001] The invention belongs to the technical field of electric digital data processing, and in particular relates to a method and device for calculating the ampacity of a cable when there is water accumulation in an electric power pipe. Background technique [0002] In most of the southern regions of our country, due to the rainy weather and the shallow groundwater level, it is inevitable that the power pipes will seep into the groundwater, and even the cables in some urban pipe projects have been soaked in stagnant water for a long time, even after the implementation of mechanical drainage. There is still a small amount of accumulated water in the pipe. Through the investigation of power pipes in a certain area of ​​Jiangsu, it is found that most of the power pipes in the city have accumulated water, and most of the running 10kV cables are soaked in accumulated water, and the existence of accumulated water has an impact on the carrying capacity of power cab...

AI Technical Summary

Problems solved by technology

Through the investigation of power pipes in a certain area of ​​Jiangsu, it is found that most of the power pipes in the city have accumulated water, and most of the running 10kV cables are soaked in accumulated water, and the existence of accumulated water has an impact on the carrying capacity of power cables It is very large. When there is water accumulation in the power pipe in the actual project, the existing calculation scheme of cable ampacity has defects, and it is impossible to obtain more accurate calculation results.

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