10kV high-voltage switchgear has a large number and a wide range of applications, and its insulation level is very important to the safe operation of the power grid.
If an insulation accident occurs in the 10kV high-voltage switchgear, the harm will cause damage to the equipment in the slightest, and cause large-scale power outages in severe cases, causing irreparable losses to the country. Therefore, this problem must be seriously studied and effectively solved.
TWO SUGGESTIONS
1 The design and manufacturing department of 10kV high-voltage switchgear should strictly implement the relevant insulation standards, and control the insulation gap and the quality of accessories.
2 The users of 10kV high-voltage switchgear must do the AC withstand voltage test before the equipment is put into operation. If the test results do not meet the relevant provisions of the "Preventive Test Regulations", they should resolutely return the goods to the 10kV high-voltage switchgear in operation. The switchgear should be fully maintained and overhauled, and the operating environment should be improved as much as possible. Common Defects and Causes
The supporting accessories have poor insulation performance
There are many manufacturers of 10kV high-voltage switchgear in my country. In order to reduce costs, some manufacturers use matching accessories with low insulation levels, which reduces the pollution flashover voltage of the entire switchgear and fails to meet the rated standard requirements.
In accordance with the "6 ~ 10kV High Voltage Switchgear Selection Principles" and combined with actual operating experience, the author believes that the surface insulation creepage ratio distance of accessories for 10kV high voltage switchgear should not be lower than the following requirements: porcelain insulators 18mm/kV, Organic insulation 20mm/kV.
Air insulation gap is small
For a long time, some high-voltage switchgear manufacturers have not strictly implemented the relevant technical standards, so that the phase-to-phase and phase-to-ground air insulation gaps between the charged bodies in some 10kV high-voltage switchgear cabinets currently in operation are mostly 100-125mm between.
As pure air-insulated electrical equipment, the "Technical Regulations for Design of High-Voltage Power Distribution Devices" clearly stipulates that the minimum clearance of pure air insulation for 10kV systems is 125mm. From the results of the AC withstand voltage test, combined with the accident analysis, it can be seen that if the minimum air insulation gap between phases and phases and between phases and ground of the charged body in the 10kV high-voltage switchgear cabinet is less than 125mm, the capacity will cause an accident.
Air gaps should not be overlooked when using composite insulation
In some 10kV high-voltage switchgear, partitions made of insulating materials are installed to form a composite insulation model such as charged body-air gap-insulation partition-grounding body. From the actual situation, when using this kind of composite insulation, the air gap cannot be ignored, and the minimum air gap is not less than 30mm, otherwise it is easy to cause insulation accidents.
Poor operating environment and low maintenance quality
Generally speaking, the operating environment of 10kV high-voltage switchgear is poor, and it is often attacked by dust, smoke, steam, etc., which causes the surface of the insulating layer to be corroded, and conductive substances are formed to form insulation defects.
There are also individual switchgear users who do not pay attention to the inspection and maintenance of equipment, and cannot find and eliminate various insulation defects in time, which eventually leads to insulation accidents.
