The first is the fault caused by the influence of ambient temperature on low-voltage electrical appliances
The low-voltage apparatus in the stainless steel distribution box is composed of fuse, AC contactor, residual current action protector, capacitor and meter. These low-voltage electrical appliances are designed and manufactured in accordance with gb1497 basic standard for low voltage electrical appliances, and their normal working conditions are specified accordingly: the upper limit of ambient air temperature is not more than 40 ℃; the average value of ambient air temperature for 24 hours is not more than 35 ℃; the lower limit of ambient air temperature is not less than - 5 ℃ or - 25 ℃. The stainless steel distribution box reconstructed by rural power grid operates outdoors. It not only generates high temperature by direct sunlight, but also generates heat by itself. Therefore, in the hot summer season, the temperature in the stainless steel distribution box will reach more than 60 ℃, which greatly exceeds the specified ambient temperature of these electrical appliances. Therefore, the electrical appliances in the stainless steel distribution box will occur Failure caused by overheating of components.
Second, faults caused by product quality
In the transformation of rural power grid, due to the large number of stainless steel distribution boxes and short construction period, the distribution box factory needs the supply time of low-voltage electrical appliances in a hurry and a large number, resulting in the phenomenon that the requirements for product quality are not strict, resulting in the failure of some products soon after they are put into operation. For example, some models of AC contactors cannot operate because the closing coil of contactors is burnt out soon after the distribution box is put into operation. Some businessmen, just to make money, regardless of quality, this problem, stainless steel distribution box box is not able to solve.
Third, faults caused by improper selection of electrical appliances in the stainless steel distribution box
Due to the improper selection of AC contactor capacity in manufacturing, the installation of AC contactors with the same capacity for different outgoing circuits without considering the imbalance of three-phase load, and the failure to improve the current level selection of some outgoing contactors based on the normal selection of models, resulting in the burning out of AC contactors during operation in high temperature seasons in summer situation. In the transformation of rural power grid, a lot of low-voltage electrical equipment purchased by the state does not require high quality. The general requirement is that it can only be used. Therefore, users have many problems in the use process, and spend a lot of money.