The 10kV high voltage switchgear has a large number and a wide range of applications, and its insulation level is of great importance to the safe operation of the power grid. If an insulation accident occurs in a 10kV high-voltage switchgear, the damage may be minor, which may cause equipment damage, or cause a large-scale power outage, and cause irreparable losses to the country.
Therefore, the problem must be studied carefully and solved in earnest.
Common defects and causes
1. Small air insulation gap
For a long time, some high-voltage switchgear manufacturers have not strictly implemented the relevant technical standards, so that the air insulation gaps between the phases and the phases and the ground between the live parts of the currently operating 10kV high-voltage switchgear cabinets are mostly 100 ~ 125mm between.
As a pure air-insulated electrical equipment, the “Technical Regulations for the Design of High-Voltage Power Distribution Equipment” clearly stipulates that the minimum gap of pure air insulation for a 10kV system is 125mm.
From the results of the AC withstand voltage test, combined with the accident analysis, it can be seen that the minimum air insulation gap between the phases and the phase and the ground of the charged body in the 10kV high voltage switchgear cabinet is less than 125mm, the capacity will cause an accident.
2. Poor insulation performance of supporting accessories
There are many manufacturers of 10kV high-voltage switchgear in China. In order to reduce costs, some manufacturers use accessories with lower insulation level, which causes the pollution flashover voltage of the whole switchgear to decrease, which does not 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 creepage creepage ratio of the accessories of the 10kV high voltage switchgear should not be lower than the following requirements: porcelain insulation 18mm/kV, Organic insulation 20mm/kV.
3. When using composite insulation, air gaps should not be ignored
In some 10kV high-voltage switchgear, partitions made of insulating materials are added to form a composite insulation mode of charged body-air gap-insulating 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.
4. 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., causing the surface of the insulating layer to be corroded, generating conductive objects, and forming insulation defects.
There are also individual switchgear users who do not pay attention to the overhaul and maintenance of the equipment, and cannot find and eliminate various insulation defects in time, which will eventually lead to the occurrence of insulation accidents.
10kV high voltage switch cabinet defect suggestion
1. The design and manufacturing department of 10kV high-voltage switchgear shall strictly implement the relevant insulation standards, and check the insulation clearance and the quality of accessories.
2. The user of the 10kV high-voltage switchgear must do an AC withstand voltage test before the equipment is put into operation. If the test result does not meet the relevant provisions of the “Preventive Test Procedure”, it shall resolutely handle the return; 10kV high-voltage switchgear should be fully maintained and overhauled, and the operating environment should be improved as much as possible.
Post time: Oct-23-2021