Analysis of two dehumidification schemes for power distribution cabinet

Dehumidification mode of distribution cabinet:

Terminal box, mechanism box, complete set of switch cabinet, distribution cabinet and other cabinet equipment are important components of substation, and their internal components have high requirements for humidity. If the internal humidity is too high, it will reduce the insulation level of internal components, and it is easy to produce mold, resulting in equipment corrosion, which is not conducive to the safe operation of the equipment. Shenzhen Wharton Electric Technology Co., Ltd. has developed wt series intelligent semiconductor dehumidifier for distribution cabinet equipment, which has achieved good results after being put into application in the market.

The equipment spacing in terminal box, mechanism box, complete switch cabinet and distribution cabinet is small. If the humidity is too high, it will cause insulation decline and even electrical flashover, resulting in AC and DC grounding from time to time, which will have an adverse impact on the safe operation of the equipment. Therefore, certain measures need to be taken to improve the moisture-proof performance of the above distribution box and cabinet equipment and ensure its internal dryness. High humidity will produce corrosion and mold. Corrosion and mold are two major factors affecting the use function and service life of electronic components.

Traditional dehumidification measures for distribution box and cabinet equipment (adding heater)

At present, it is widely used in the power system to match the heater for the humidity probe. When the humidity is too high, start the heater to heat the wet air and make the heated wet and hot air rise. When the hot and humid air rises and touches the top of the box, condensation will occur after cooling, which will reduce the insulation level, which is not conducive to the safe operation of the equipment. The moisture still remains inside the box, which can not effectively reduce the internal humidity of the box equipment. In the south, due to the high temperature and humidity in summer, coupled with the heat generated by the operating elements in the cabinet, the skin of various cables is seriously aged, which is easy to cause equipment failure.

Dehumidification measures for distribution box and cabinet equipment

According to the field observation results of the distribution box, if the humidity in the distribution box is large and there is condensation, the moisture (condensation) in the box will be transformed into steam after the heater works. Due to the lack of good discharge channel, it is difficult to eliminate the internal moisture and cause excessive humidity at the top of the box. Therefore, the following two problems need to be solved to truly ensure the moisture-proof and dehumidification effect of the box equipment.

1. Prevent excessive local humidity

Using ordinary heaters, the water seeping into the box is gasified, and the hot and humid water vapor rises to the top, resulting in excessive humidity at the top of the box and easy to form condensation. Its danger is self-evident. Therefore, the gas circulation in the small environment in the cabinet must be promoted to ensure uniform humidity everywhere.

2. Prevent the internal temperature of the distribution cabinet from being too high

The cabinet temperature is too high. Firstly, it seriously affects the heat dissipation of electronic components and significantly reduces the service life. Secondly, the cable skin is seriously aged, which is easy to cause equipment failure or loss of some functions of the equipment. Therefore, it is not appropriate to increase the ambient temperature of the cabinet equipment during internal dehumidification.