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Selection and normal use of electrical components in the distribution box
- Dec 14, 2018 -

Selection of electrical components in the distribution box and normal use The most important electrical components in the distribution box include: isolating switch, which is usually used as a safety isolation function for the incoming main switch; small circuit breaker for overload and short circuit protection; leakage circuit breaker In addition to the role of a small circuit breaker, it also has a leakage protection function to protect the human body from electric shock. The selection of the built-in components should be based on whether it meets the requirements of national standards and certification regulations (such as 3C certification), whether the protection characteristics meet the requirements of the protected circuit and the selectivity of the upper and lower protection circuits and the installation characteristics of the components. Safe protection.

The most common problem is that the front and rear protection characteristics are not coordinated, the circuit breaker characteristics are not properly selected, the leakage circuit breakers are improperly selected, and there are unqualified components. These problems are caused by the designer's failure to correctly understand the performance indicators of various electrical components, and on the other hand, due to the irregular construction of the procurement. GB50096 "Residential Design Code" stipulates: "Every house's air conditioning power outlets Power outlets and lighting should be designed separately; kitchen power outlets and bathroom power outlets should be provided with independent circuits. With the popularization of large-capacity household appliances such as air conditioners, electric water heaters, microwave ovens, etc. in general households, in order to reduce line temperature rise and harmonic hazards, extend line life and reduce electrical fire hazard, separate circuit distribution of the above-mentioned large-capacity household appliances It is very necessary. In the household distribution box, it is common to distribute the air conditioning power socket with other power outlets, and the bathroom power socket and the kitchen socket are combined into one circuit. Obviously, the above requirements are not met, which will undoubtedly accelerate the aging of the line and increase the risk of electrical fire. .

The most common distribution box in practical applications is embedded, which is aesthetically pleasing and does not take up space. After installation, the enclosure is not easy to dissipate heat, and because the components in the distribution box are modularized, the electrical components are closely packed side by side, which is significantly different from the normal use conditions. The most important electrical component used in the distribution box is the miniature circuit breaker. When the miniature circuit breaker works normally, it is determined by the test that the rated current of the circuit breaker is a key factor. How much rated current should be used for each branch circuit breaker in the distribution box? Modern lighting devices, whether for household or other applications, have few lamps with pure resistance. Generally, energy-saving lamps, fluorescent lamps, etc., and air conditioners are the most common. The load is nonlinear. The load makes the current waveform extremely irregular, and the ordinary ammeter cannot measure the harmonic current. Obviously, it is not appropriate to select the rated current of the breaker according to the calculated current. Therefore, it is necessary to make appropriate according to the composition of the actual load. Consideration.