The function of air switch in the circuit is to automatically break the circuit when overload, short circuit and voltage loss exceed the allowable limit occur, and to make and break the circuit infrequently under normal conditions. The function of the wire should be able to bear the needs of the maximum load current, and be able to withstand a certain mechanical pull, a certain voltage, etc.
The problem now is that the air switch doesn’t trip when all the wires are on fire. According to the above analysis, we can see as follows:
1、 Wrong selection of current carrying capacity of wire. Generally, the selection of wires should meet the requirements of safety, correctness and resistance to mechanical tension. Generally, the safe current carrying capacity of wires should be greater than 1.5 times of the rated current of electric load. Different wires should be selected according to different wiring of the device. Such as plastic sheathed wire, plastic cable, single strand, multi strand plastic copper core, aluminum core and other wires. Different wires should also be selected according to different places. Such as dust, high temperature, humidity, cultural and entertainment places, stage and so on have different requirements. The selection of wires should be in line with the national standard. Fake wires should be refused to install. Electrical installation must be clear about the electrical requirements. It is necessary to know the maximum rated current of power consumption in order to correctly select the wire specifications that meet the requirements.
2、 The rated current of air switch is wrong. In the case that the air switch doesn’t trip because the wire has burned due to heating, it shows that the rated current of the air switch is wrong. In the circuit, the neutral switch is the main power switch. The general selection principle of rated current of air switch is 1.2 times of the total rated current of line electrical appliances. When the line is overloaded, the breaking will delay or even refuse to operate. This air switch doesn’t work. If the switch is too small to withstand large current, it will trip and affect normal use. In addition, the selection of air switch should also pay attention to the adaptability of the place. The adaptability of rated current should be considered in the selection of air switch. Different air switches are selected for breaking capacity, sensitivity and fast action.
3、 There may be irregularities in the line device. The installation shall be standardized in the line. Comply with the electrical pressure regulation and carry out the electrical installation according to the requirements. And the inspection should also comply with the requirements of low standard acceptance to ensure safety.