Box-type substations are compact power facilities that integrate high-voltage switchgear, transformers, and low-voltage distribution equipment. Overheating caused by internal short circuits can directly lead to insulation degradation, component damage, and even fire risks. A systematic solution to this problem requires seven key aspects: short circuit diagnosis, emergency response measures, cooling system optimization, equipment maintenance and management, safety upgrades, operating environment improvements, and intelligent monitoring.
Internal short circuits are a direct cause of overheating in box-type substations. The root causes may include degraded insulation, loose connections, component aging, or external factors (such as lightning strikes or intrusion by small animals) that cause phase-to-phase or ground shorts. When a short circuit occurs, the current increases abnormally, generating significant Joule heating that rapidly increases conductor temperatures and triggers localized arcing, further exacerbating the temperature rise. Immediately disconnect power to the faulty area to prevent the short circuit from spreading. Use infrared thermometers and partial discharge detectors to locate the short circuit point. Inspect key areas such as cable connectors, circuit breaker contacts, and transformer windings for signs of burns or insulation breakdown.
During the emergency response phase, the box-type substation's emergency plan must be activated first. Shut off the incoming and outgoing line switches in the faulty compartment to isolate the short-circuit area and prevent damage to adjacent equipment caused by high temperatures. Simultaneously, activate the forced exhaust system to expel hot air from the box and reduce the overall temperature. If the temperature continues to rise to a dangerous threshold, activate backup cooling devices, such as temporary air cooling equipment or mobile air conditioners, to prevent transformer oil deterioration or insulation carbonization. Additionally, check the box's seal to prevent the ingress of humid air and the recurrence of short circuits.
Optimizing the cooling system is key to long-term solutions to overheating. The box-type substation's cooling design must balance natural and mechanical ventilation: natural ventilation relies on louvers on the top and vents on the sides to create convection, while mechanical ventilation uses axial fans to force air flow. If the original design's cooling capacity is insufficient, add ducts or adjust the fan's position to direct cooling air directly to heat-generating areas such as the transformer windings and high-voltage switchgear. For high-power box-type substations, liquid cooling technology, such as a coolant circulation system or transformer oil circulation device, can also be introduced. This transfers heat to the external environment through a heat exchanger, achieving more efficient temperature control.
Equipment maintenance and management require a regular inspection and preventive testing system. Monthly checks should be conducted on the tightness of cable connectors, busbars, and circuit breaker contacts, clearing away dust and debris to prevent local overheating caused by poor contact. Quarterly insulation resistance tests, DC resistance tests, and partial discharge tests should be conducted to promptly detect insulation defects. Annual transformer oil sampling should be performed to monitor moisture and gas content to determine if there are any internal overheating or arc faults. Furthermore, equipment health records should be established, recording temperature profiles, load changes, and fault history to provide a basis for condition-based maintenance.
Safety upgrades should focus on moisture, dust, and small animal protection. Use sealing strips or foam material to fill the box joints. Install waterproof connectors and dust covers at the cable entry and exit holes to prevent the intrusion of humid air and dust. Install metal filters at the vents to prevent the entry of small animals such as birds and rodents. Provide drainage gutters at the bottom of the box to prevent rainwater accumulation. Additionally, install temperature and humidity sensors inside the box to automatically activate the dehumidifier when the ambient humidity exceeds a threshold, reducing the risk of short circuits.
To improve the operating environment, pay attention to the site selection and layout of the box-type substation. Avoid installing the box-type substation in low-lying areas or poorly ventilated areas to prevent rainwater backflow and heat accumulation. If there are high-temperature heat sources nearby (such as boiler rooms or surfaces exposed to direct sunlight), add awnings or reflective coatings to reduce solar radiation absorption. In dusty environments, install green belts or dust screens around the box to reduce dust accumulation.
Intelligent monitoring is a key measure to enhance the safety of box-type substations. By installing multiple temperature sensors, current transformers, and smoke detectors, real-time equipment operating data is collected and uploaded to a centralized monitoring platform. When the temperature exceeds a preset threshold, the system automatically triggers an alarm and notifies maintenance personnel. Simultaneously, using big data analytics, it predicts equipment overheating trends and enables proactive maintenance planning. Furthermore, the intelligent temperature control system automatically adjusts fan speed and cooling pump flow based on load changes, achieving a balance between dynamic energy conservation and safe operation.
