Innovative air duct-enhanced thermal management and natural convection heat transfer intensification in the busbar compartment of an air-insulated medium-voltage switchgear

Abstract

In the current development of medium-voltage switchgear systems, there is a strong demand for increasing electrical efficiency, performance, and reliability, necessitating effective thermal management. However, there is only limited knowledge about the thermal behaviour and possibilities for cooling intensification of air-insulated medium-voltage switchgears, frequently used in practice. The study presents an innovative way to enhance the cooling of a busbar compartment of an air-insulated medium voltage switchgear. This comprised a thermally efficient design of air ducts for enhanced convection. Several designs were proposed and investigated. The investigations involved multi-physical computer simulations, experimental investigations, and testing, including standardised temperature rise tests. Good agreement between simulations and experiments was achieved with an average root mean squared error of about 2.8 degrees C. Shape-optimisation of the proposed design with a two-channel ventilation duct system led to a 57 % decrease in the pressure drop of the ducts, reducing the relative temperature rise in the busbar compartment by about 10 %- 25 % compared to other investigated designs. Such a superiority was also confirmed in experimental investigations in a certified laboratory. This makes the proposed design very promising for enhanced cooling and easy adaptation of the switchgear for various applications, including the increase in its current rating.