Although the weather is not yet hot, different types of faults have occurred to the residual current operated protector in the distribution box, such as: (1) fault of residual current operated protector; (2) fault of converter contactor; (3) fault of metering energy meter; (4) fault caused by internal wiring; (5) fault of burned fuse base and motor caused by phase loss, etc. At present, the non-metallic meter box manufacturers have made an analysis of the problems caused by the influence of the ambient temperature on the low-voltage electrical appliances.
Faults caused by the influence of ambient temperature on low-voltage electrical appliances
① Reactive compensation capacitors and fuses operating at high temperature will also shorten their service life.
② The electronic products in the distribution box, such as residual current operated protector and electronic meter, will seriously affect the service life of the product when operating at high temperature, and also affect the stability of the protector performance, the reliability of action and the accuracy of measurement.
③ All kinds of low-voltage electrical appliances, most of them are class a insulation, and their limit allowable temperature rise in long-term operation is 65 ℃. The high temperature in the distribution box and the production of the meter control box make it difficult for the internal heat of the low-voltage electrical appliances to radiate outwards during operation, so it will burn out due to the aging of the insulation after a certain period of time; the plastic insulated wire will also be damaged due to the aging of the heat.
Causes of distribution box failure caused by ambient temperature
The low-voltage apparatus in the distribution box is composed of fuse, AC contactor, residual current action protector, capacitor and electrical measurement digital 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 for the production of Dongguan GCK low-voltage cabinet 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 ℃.
In the hot and hot weather in summer, the low-voltage electrical appliances in the distribution box will generate heat in their own operation. In addition, the external environment temperature is also high, and the temperature in the box will reach more than + 60 ℃. At this time, the temperature greatly exceeds the environmental temperature specified in the national standard of these electrical appliances, which will cause the failure of the distribution box. Reducing the temperature of distribution box and improving the technology of distribution box are the methods to reduce the failure of distribution box.