According to statistical data, the percentage of external faults in various types of power equipment exceeds 90% of the total number of faults, while the proportion of internal faults is less than 5%
. In terms of numbers, external faults far outnumber internal faults. However, in terms of the risks and losses that may arise from the malfunction. For example, when the transformer bushing is short of oil or internally damp, it may cause discharge and result in bushing explosion, and even cause serious damage to the transformer body. Its destructive power is hundreds or even thousands of times greater. External faults such as cable clamps overheating and burning out.
The main drawbacks of internal overheating in power equipment include
(1) Overheating of the enclosed busbar of the generator;
(2) Transformer winding;
(3) Overheating of iron core and sleeve;
(4) Overheating caused by poor contact of low oil circuit breaker contacts;
(5) Overheating caused by poor iron core in voltage transformers;
(6) Internal discharge and explosion hazards caused by poor performance or lack of oil;
(7) Overheating of current transformers caused by poor contact;
(8) Various types of high-voltage equipment are equipped with insulation layers that may experience increased dielectric loss, moisture, aging, and other factors, leading to temperature rise and potential risks of thermal breakdown and explosion;
(9) Overheating caused by moisture and aging due to poor sealing or lack of oil at the three-phase bifurcation of high-voltage cable heads;
(10) Fever or partial discharge caused by poor sealing of the false oil level in the high-voltage bushing;
(11) The temperature rise caused by various faults inside the lightning arrester;
(12) Various overheating defects and faults caused by reactors and wave blockers.
Characteristics of Internal Overheating Disadvantages in High Voltage Electrical Equipment
The fault point is sealed in the edge material or metal shell, because the penetration of infrared radiation is weak, and infrared radiation cannot penetrate the edge material at all
Equipped with a casing, it is not possible to directly install and detect internal thermal defects using infrared thermal imaging. But the disadvantage of internal overheating is that it usually lasts for a long time and is more
Stable power.
The heat at the fault point can be transferred through process heat conduction and convection displacement methods to the conductors or edge materials around the fault point, leading to heat transfer
The temperature rise in these areas not only affects the conductors that are electrically adjacent to them, but also makes them good conductors for heat transfer, resulting in a significant temperature rise.
