Rules and Causes of Overheating of Electrical Equipment

Rules and Causes of Overheating of Electrical Equipment

1. External thermal fault

External thermal failure of electrical equipment mainly refers to the exposed joint due to poor crimping and other reasons, under the action of high current, the joint temperature increases, the contact resistance increases, and the vicious cycle causes hidden dangers. Such failures account for more than 90% of external thermal failures. Statistics of thousands of external thermal failures detected in recent years.The thermal failure of wire clamp and brake contact accounts for 77% of the entire external thermal failure. Their average temperature rise is about 30 ° C. The average temperature rise of other external joints is between 20-25 ° C. Combined with the detection experience , according to the number of temperature rises. External failures can be divided into three types: minor, general and serious.

2. Internal thermal failure

The internal thermal failure of high voltage electrical equipment is characterized by the fault point is sealed in the insulating material or metal shell, such as cable, the internal thermal failure is generally heating for a long time and relatively stable, and the heat transfer occurs with the conductor or insulation material around the fault point, so that the local temperature can be detected by the temperature rise of the surrounding material to diagnose the internal fault of high voltage electrical equipment (such as cable).

3. the part of the cable overheating fault

According to power accident analysis, cable overheating fault can cause fire leading to large area cable burn damage, resulting in forced shutdown, unable to resume production in a short time, resulting in significant economic losses. Through the analysis of the accident, the overheating of the cable joint is the direct cause of the cable fire, the overheating of the cable joint is because the joint pressure joint is not tight, the joint oxidation leads to the contact resistance is too large, the long-term high temperature operation makes the insulation drop and breakdown, and finally leads to the occurrence of the cable fire.

4. cable overheating fault prediction method

According to the analysis of cable overheating fault characteristics, the effective way to prevent cable overheating and fire is to timely monitor the temperature of the cable joint, analyze the aging degree of the cable joint according to the change trend of the joint temperature, and issue an alarm before the real failure of the cable joint.
The cables with joint overheating are mostly high-voltage cables above 6KV. Due to the high voltage level, conventional temperature sensors cannot meet the safety needs, and the traditional optical fiber temperature measurement system has the disadvantage of long scanning time. PIONEER-P fiber grating temperature measurement system is the best choice to monitor the overheating fault of high-voltage live equipment.


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