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Analysis of the Main Causes of Excessive Temperature Rise in Box-Type Substations
Time:
2026-02-12
The primary causes of excessive temperature rise in packaged substations include internal faults, inadequate heat dissipation, and external environmental factors; systematic troubleshooting and targeted measures are therefore required.
Internal fault
1. Winding or core short circuit: Interturn short circuits in the windings or multiple-point grounding of the core can induce additional eddy currents, leading to localized overheating.
2. Poor contact in the tap changer: Increased contact resistance leads to overheating, which can be identified through DC resistance testing and oil sample analysis.
3. Temperature sensor failure: The display shows an abnormal temperature reading, but the actual temperature is normal; on-site verification with an infrared thermometer is required.
Cooling system issue
1. Obstructed ventilation: Accumulation of dust or blockage at the air inlets and outlets can significantly reduce cooling efficiency; therefore, regular cleaning and inspection of fan operation are essential.
2. Cooling system failure: If the fan stops, the oil pump malfunctions, or the radiator becomes clogged with dirt, the system must be promptly inspected and repaired, or the standby cooling system must be activated.
3. Design defects in the enclosure: Some European-style pad-mounted transformers have enclosures rated for 20 kV or 30 kV, which leads to artificially elevated operating temperatures, thereby exacerbating losses and accelerating aging.
External Operating Conditions
1. Overload operation: When the load current exceeds the rated value, copper losses increase, leading to a rise in temperature. The load should be adjusted or the operating mode optimized.
2. Excessive ambient temperature: During summer heat or when operating in enclosed spaces, heat dissipation can be challenging. It is recommended to reduce the load rate by approximately 10% during peak temperature periods.
3. Low oil level or degraded oil quality: This impairs insulation and cooling performance; therefore, the oil level should be checked regularly, and oil analysis should be conducted.
Recommended processing procedure:
First, use infrared thermography to locate hot spots and verify the accuracy of the temperature-measuring equipment; then inspect the cooling system and ventilation conditions. If the issue persists, the equipment should be shut down for electrical testing—such as winding resistance and no-load loss measurements—to diagnose internal faults.
Contact
Address: No. 113, Huancheng Road, Huangchuan County, Henan Province
Tel: +86-376-3985688
Email: zhjvip001@163.com
Address: No. 113, Huancheng Road, Huangchuan County, Henan Province
Tel：+86-376-3985688
Email：zhjvip001@163.com
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