The ability to control temperature rise in low-voltage switchgear directly impacts its operational stability and service life. Structural design optimization requires comprehensive considerations of heat conduction paths, heat dissipation efficiency, and material selection. When planning the heat conduction paths, the layout of key contacts and conductor bars should adhere to the "short, straight, and thick" principle. This shortens the current path, minimizes bend angles, and increases the conductor cross-sectional area to reduce resistance and minimize Joule heating. For example, the main circuit conductor bars should be designed as straight or L-shaped to avoid localized current density increases caused by complex bends. Furthermore, silver-based alloy plating should be applied to the contact surfaces, leveraging its high conductivity and oxidation resistance to ensure a stable low contact resistance and reduce heat accumulation at the source.
Optimizing heat dissipation channels requires a combination of natural convection and forced cooling. For natural convection cooling, the heat sink design of the device casing must balance surface area and air flow. Typically, straight fins are arranged in parallel in a longitudinal direction, with a spacing between fins within 8-15 mm. This ensures smooth air flow between the fins and improves heat exchange efficiency by increasing the heat dissipation area. In forced cooling scenarios, such as high loads or enclosed environments, axial fans can be integrated into the top or side of the device. Intelligent temperature control modules control the fan's on/off function. When the internal temperature exceeds a set threshold, the fan automatically activates, creating a directional airflow that accelerates heat dissipation while avoiding the energy consumption and noise issues associated with continuous fan operation.
Material selection plays a crucial role in controlling temperature rise. Conductive components should preferably be made of high-conductivity materials, such as copper alloys or pure copper, which can achieve conductivity levels exceeding 98% IACS and effectively reduce conductor losses. For components requiring both mechanical strength and conductivity, a copper-aluminum composite structure can be employed. For example, copper is used in the core layer of the conductive busbar to ensure conductivity, while aluminum is used as an outer layer to reduce weight and cost. Insulation materials should be highly heat-resistant, such as Nomex paper or silicone rubber, with a long-term operating temperature exceeding 180°C to prevent localized overheating caused by insulation aging. Inorganic fillers such as magnesium oxide can also be added to enhance the material's thermal conductivity, aiding heat transfer.
Internal airflow design is a key factor in improving heat dissipation efficiency. Clearly planned air inlets and outlets are required within the equipment. Inlets are typically located at the bottom or low side of the equipment, while outlets are located at the top or high side. This utilizes the principle of rising hot air to foster natural convection circulation. For multi-module equipment, a ventilation gap of at least 20 mm should be maintained between modules to prevent heat accumulation. Additionally, deflectors should be installed around key heat-generating components (such as circuit breaker operating mechanisms and capacitor banks) to prioritize airflow through high-temperature areas and improve local heat dissipation efficiency.
The introduction of thermal simulation technology provides a scientific basis for structural design optimization. By creating a 3D model of the equipment and importing it into thermodynamic simulation software, temperature distribution under different operating conditions can be simulated, identifying high-temperature risk points and implementing targeted improvements. For example, simulation results showed that the contact area temperature of a certain low-voltage switchgear model reached 95°C under rated load. By increasing the contact area by 30% and optimizing the heat sink layout, the temperature was reduced to 75°C under the same operating conditions, significantly improving equipment reliability.
The balance between structural sealing and heat dissipation requirements must be flexibly addressed based on the application scenario. For outdoor or humid environments, the device must utilize a sealed structure with an IP54 or higher protection rating. Thermal grease or phase change material can be filled into the sealing groove to ensure waterproof and dustproof performance while utilizing the material's thermal conductivity to transfer internal heat to the heat sink on the outer casing. For dry indoor environments, the sealing rating can be appropriately reduced, and a ventilated structure can be used to enhance air convection and further improve heat dissipation efficiency.
Controlling the temperature rise of low-voltage switchgear is a systematic project, requiring coordinated improvements across multiple dimensions, including heat conduction path optimization, heat dissipation channel design, material selection and upgrades, airflow planning, thermal simulation verification, and sealing structure balancing. In practice, a comprehensive balance must be made based on factors such as the device's load characteristics, installation environment, and cost constraints to optimally balance temperature rise control with device performance and reliability.
