BURNOUT OF TERMINAL BLOCKS IN POWER DISTRIBUTION CABINETS AND CAUSES OF IT

With the development of the electronics industry, the scope of use of terminal blocks is increasing. The improper use of a large number of terminal blocks causes frequent occurrence of terminal block burnouts, posing a serious threat to the distribution cabinet and power supply safety. The article introduces the cause of the burnout of the terminal blocks of the distribution cabinet, and puts forward the corresponding prevention and solution measures and suggestions.

Causes of Burnout of Terminal Blocks in Power Distribution Cabinets

According to the analysis of the burnout of the terminal blocks in the power distribution cabinet, it is found that the main terminal in the power distribution box often passes a large current, which is prone to thermal burnout failures, especially the caged terminal burnout accidents are more frequent. Most of the cage terminal are reed-type cage terminals. The following is an analysis of the causes of burning of the electrical component terminals and cage spring terminals in the distribution cabinet.

1.Electrical Component Terminals

There are two main reasons that lead to the heating and burning of related electrical components such as one-way and two-way main contactors and air switches. One reason is that some external factors cause the distribution cabinet to continuously vibrate, loosening the connection between the terminal and the electrical components, and the pressing force is constantly reduced, resulting in an increase in contact resistance. In the process of long-term power, it is easy to use and easily causes electrical components heat and damage to the terminals. Another reason is that the pressure contact between the terminal and the conductor of the wiring is poor, which increases the contact resistance. When the power is applied for a long time, the terminal of the electrical component is heated and burned.

2.Causes of Burnout of Spring-loaded Terminal Blocks

The cage spring terminal has the characteristics of compact structure and convenient wiring. It is also due to the tight connection between the cage spring terminals that it is not easy to find the burnt inside the cage spring terminal on the surface, which is likely to cause serious damage. The main reasons for the burning of the cage spring terminal are as follows.

1) The current-carrying conductor is hot. At present, the wiring connected to the reed-type terminal of the main line in the current distribution cabinet is 16mm wiring. The resilience of this kind of spring is relatively large, which causes the opening angle of the sheet is not enough when the distribution cabinet is connected to the wiring, so that some of the conductors of the wiring are not fully pressed into the elastic sheet, resulting in that the actual conductive area of the wire is reduced, and an abnormal temperature rise occurs when a long-term current passes. When the temperature of copper exceeds 150 ° C, the mechanical strength of copper will drop sharply, which will cause the contact pressure between the conductor and the reed to decrease, the contact resistance to increase, and the reed to heat up more seriously. In addition, the heat will also cause the contact surface of the conductor to be strongly oxidized, resulting in copper oxide. The resistance of copper oxide is often much greater than the resistance of the conductor itself, which causes a sudden increase in the amount of heat at the contact and forms a vicious cycle, leading to an electrical cabinet. The contact between the terminal and the conductor is loose, deformed, and even severely melted.

2) The cage spring terminal burns out. There are also some problems in the actual use of cage spring terminals, and terminal burnout failures often occur. The main phenomenon is burnout and melting of the terminal.

Preventive Measures and Suggestions for Burnout of Distribution Cabinets

Through the analysis and treatment of the terminal block of the power distribution cabinet and the terminal block of the electrical components, some targeted measures can be taken and can achieve good results.

1 Precautionary Measures

1) Use the crimp terminal crimping method correctly.

2) Strengthen the monitoring and control of cage terminals.

3) Strengthen the maintenance of cage terminals.

2 Suggestions for Burned Terminal Blocks in Distribution Cabinets

1) Improve the cage terminal.

2) Apply a temperature indicator to the wiring.

3) Improve the distribution cabinet door.

In the actual application process, according to the instruction manual of the terminal, a detailed work instruction book can be prepared to further improve the operating specifications and guide the site workers to operate correctly. In the use of the power distribution cabinet, pay attention to observe the state of the terminal blocks, and the infrared point temperature inspection of the main terminal blocks should be carried out regularly. If there are problems, they should be dealt timely. And the rules should be summarized and experience accumulated. Take advantage of the maintenance-free, shock-resistant, and easy-to-operate characteristics of terminal blocks to improve the electrical connection level of the distribution cabinet and ensure the safety of power supply lines.