The distribution box consists of a distribution box base and a guide rail. The two sides of the two distribution box bases are respectively fastened together by base fasteners. The guide rail clamping slot seat is clamped in the clamping slot of the base fastener. The guide rail slot seat is provided with several layers of clamping slots, and both ends of the guide rail are inserted into the card slot. The beneficial effect of this product: the height of each type of circuit breaker can be roughly unified according to the height of the guide rail. It is very convenient to use and can be suitable for various types of circuit breakers. After installation, the appearance is more beautiful, the structure is simple, the function connection is convenient, and the practicability is strong, which is convenient for installation and maintenance, and convenient for people's life.

1.1 fault caused by the influence of ambient temperature on low voltage apparatus

The low voltage apparatus in the distribution box is composed of fuse, AC contactor, residual current operated protector, capacitor and metering meter. The upper limit of ambient air temperature shall not exceed 40 ℃; the average value of ambient air temperature in 24h shall not exceed 35 ℃; the lower limit of ambient air temperature shall not be lower than - 5 ℃ or - 25 ℃.

The distribution box of rural power network transformation operates outdoors. It not only generates high temperature by direct sunlight, but also generates heat during operation. Therefore, in the high temperature season in midsummer, the temperature inside the box will reach above 60 ℃, which is much higher than the environmental temperature specified by these electrical appliances

1.2 failure caused by product quality

At that time, the quantity of low-voltage distribution boxes did not need to be improved due to the short supply time of distribution boxes. For example, some types of AC contactors can not run because of the burning of the closing coil of the contactor shortly after the distribution box is put into operation.

1.3 faults caused by improper selection of electrical appliances in distribution box

Because the capacity selection of AC contactor is not appropriate in manufacturing, AC contactor with the same capacity is installed for different outlet circuits, and the unbalanced situation of three-phase load is not considered, so the current level of some outgoing contactor can not be improved by a current level selection based on the normal selection model.