How to solve the wet outdoor box-type substation?

issuing time:2021-05-25

When the three-volt weather encounters drizzle, hot and humid weather becomes an unavoidable problem in life and an unavoidable problem in the distribution network. In order to ensure the safe and reliable operation of the power system, the dehumidification and dehumidification of electrical equipment has become a problem that the power industry needs to deal with. A big problem. To this end, this issue will bring you to focus on specific measures for moisture prevention and dehumidification of electrical equipment to ensure the safe and stable operation of electrical equipment during the rainy season.
Long-term exposure to moisture affects the safe operation of
electrical equipment. The main metal damage forms of electrical equipment are divided into corrosion, fatigue, friction, abrasion, etc., all of which have a great impact on the life of the equipment. Among them, the corrosion damage caused by moisture accounts for the largest proportion. Our country has reached or approached the international advanced level in terms of anti-loss of conventional electrical equipment, and has accumulated rich experience in manufacturing and use and maintenance. It has basically met electrical engineering applications under conventional and general use conditions, but for electrical equipment in special environments Applied research under the conditions is far from enough.
Especially the electrical equipment exposed to the outdoor environment for a long time should pay more attention to the moisture-proof and moisture-proof in the rainy season. Outdoor 35 kV box-type substation is a kind of organic combination of high-voltage switchgear, distribution transformer and low-voltage power distribution device, installed in a movable steel structure box. It is currently widely used in urban network construction and transformation. .
When the rainy season comes, when the air in the high-pressure room is directly connected to the outside world, the outdoor high-humidity air directly penetrates into the high-pressure room, and the high-pressure room is usually arranged on the first floor of the substation. After the surface moisture and the moisture in the cable trench gather, the humidity in the high-pressure room is very high. , Which seriously affects the safe operation of electrical equipment. Therefore, moisture-proof and moisture-proof outdoor 35 kV box-type substation is very important.
 Safety problems caused by long-term dampness of electrical equipment are not uncommon. Inspectors from a power supply company found that a 35 kV high-voltage room was filled with smoke and smelled of burning, and the 35 kV line protection tripped. Experts and technicians were then organized to conduct a comprehensive inspection of the equipment and found that the switch bay busbar and the wall bushing had serious discharge. After the test, the 35 kV bus bar and the contact box of the trolley switch and the contact box current transformer have a serious drop in insulation to ground, only 3~5 megohms. Through the field equipment accident investigation and checking the equipment operation records, relevant experts analyzed the cause The long-term dampness of the equipment causes internal deterioration of the insulation and eventually this insulation breakdown fault occurs.
According to years of experience in electrical environment management, when the rainy season comes, the humidity in the high-pressure room is as high as 95%. Long-term exposure to high humidity can easily cause condensation, and condensation often causes electrical discharge in the high-voltage cabinet, and even causes the switch cabinet to explode. In addition, long-term operation of the electrical equipment in the high-voltage chamber in a high-humidity and high-temperature environment can easily cause serious corrosion of various metal materials, causing the switch cabinet to refuse to move and affecting the normal operation of the knife switch. If the moisture in the 35kV substation cannot be resolved in time, then malfunctions caused by moisture may occur at any time.
The factors that affect the corrosion of electrical equipment are more complicated. With different climates and regions, the surrounding air temperature, humidity, impurity composition and concentration, etc. are very different, and the degree of corrosion of electrical equipment is also different. Under normal circumstances, the moisture impact of outdoor box-type substations is concentrated on the following main problems.
    First, because there is no ventilation facility in the cable room under the box, the surrounding walls and floor will not be dry for a long time. The sealing around the bottom and periphery of the box is not perfect. In rainy days, water will seep from the outside to the inside of the wall of the box and enter the surrounding walls under the cable room, which will cause the air in the bottom of the box to be humid. Second, because the outer surface of the box and cable is surrounded by grass, rainwater is stored in the soil and gradually seeps into the inner wall of the cable. The bottom of the box body of the high-voltage switchgear and the cable room are not fully sealed, and there is mutual air flow between the box body and the cable room. Third, the installation position of the exhaust fan on the top of the box is unreasonable. Whenever the exhaust fan is turned on, the humid air in the cable room will circulate into the box. When the cold and humid air flows through the electrical equipment, it will form water droplets and adhere to the surface of the insulation part of the electrical equipment. on. Fourth, there is only a small heating plate in the cable outlet space of the switch cabinet, and the temperature and humidity controller is installed in the front of the cabinet, which fails to truly reflect the temperature and humidity value of the high-voltage equipment space in the cabinet.
Reasonable moisture-proof measures in substations can avoid the impact of moisture on electrical equipment. According to different environmental conditions, measures such as removing moisture from the cable room, sealing the box and cable room, keeping the box and switch cabinet dry, etc., are rectified, and the moisture-proof measures are specifically improved. In addition, through technical means, continuous upgrading of electrical equipment series dehumidification products has become a future trend to avoid moisture in electrical equipment.
In addition, according to the impact of the rainy season on the box-type substation, in addition to installing reasonable dehumidification and anti-dew products, the substation operation and management personnel also need to strengthen the comprehensive moisture-proof standard work. Before the rainy season comes, substation operators must take waterproof, moisture-proof and plugging measures for cable trenches and switch cabinet holes in time to ensure the insulation of the cable trenches in the high-voltage room of the substation and prevent the direct intrusion of moisture from the cable trenches into the high-voltage switchgear.