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Causes and preventive measures of burning terminals of distribution cabinet terminals

  • DATE:2018/4/14 15:57:35

Causes and preventive measures of burning terminals of distribution cabinet terminals


The connection terminal is an accessory product for realizing electrical connection. It is divided into the category of connectors in industry. With the increasing degree of industrial automation and stricter and stricter industrial control requirements, the consumption of terminals is rising. The cable terminal is an important part of the distribution cabinet and the complete operation of the cable terminal. If the connection is bad, the contact resistance will be increased, the insulation aging and heat loss of the terminals or cables will be caused, which cause serious danger to the distribution cabinet and the safety of the power supply. Causes and preventive measures for the burning of the terminals of the cabinets:



Cause of burning loss of wiring terminal of distribution cabinet
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1. Heating and burning loss of wiring terminals of electrical components
There are two main reasons for heating and burnout of one or two main contactors and air switches and other related electrical components. One reason is that some external factors (such as the pavement vibration when large vehicles pass through) cause the continuous vibration of the distribution cabinet, which makes the connection between the connection terminals and electrical components loosened, the compacting force decreasing continuously, causing the increase of contact resistance, which will easily cause the heating and burning of the wiring terminals of the electrical components in the process of long-term electrifying; the other is the other. The reason is that the connection terminal and the conductor of the wiring terminal have bad pressure connection, which causes the increase of contact resistance. In the long run, the connection terminals of the electrical components are burned and burned.

2, the cause of the burning loss of the spring terminal
The cage type spring terminal has the characteristics of compact structure and convenient connection. It is also due to the close connection between the cage spring terminals. It is not easy to find the burning loss of the cage type spring terminal terminal on the surface. It is easy to cause more serious burn loss, and the current reed terminal of the main trunk line in the distribution cabinet. The wiring of the wires used is the 16mm? Line. The reed has a large elastic force, which leads to the insufficient opening angle of the reed when the distribution cabinet is connected to the wiring line, which causes the partial conductor of the wiring to not be completely pressed into the bullet, which reduces the actual conducting area of the wire and produces abnormal heating up when the long current passes through. Experimental research shows that metal conductor will suffer mechanical strength drop due to annealing at high temperature. When the temperature of copper exceeds 150 degrees C, the mechanical strength of copper drops sharply, which leads to the decrease of contact pressure between the conductor and the reed, the increase of contact resistance and the more serious heat of the reed. In addition, the heating will also cause a strong oxidation of the contact surface of the conductor, and the resistance will tend to be much larger than the resistance of the conductor itself (some can reach dozens or even larger) of copper oxide, which greatly increases the contact area of the resistance, increases the calorific value of the contact and forms a vicious cycle and leads to the connection of the electric cabinet. The contact between wire terminals and conductors is loose and deformed. Even when it is serious, there will be a melting phenomenon.


Prevention measures for burning loss of wiring terminal of distribution cabinet

1. The correct use of cage terminal pressing method

The cage type terminal supporting tool in operation, such as cold press pliers, stripping pliers, screwdrivers and other tools. The stripping length of the line end is carried out according to the requirements of various terminals. The automatic stripping machine can be used for large scale stripping operation, and the length of the stripping line is fixed. When pressing, we should strictly follow the operation rules and check the cold pressing tools regularly. In actual operation, when the reed of the cage spring terminal is found to press the wiring phenomenon of the insulation layer of the wiring line, the connection must be repressed, and the range of the wire conductor entering the reed must be guaranteed to be between 10mm and 15mm. If the part of the conductor is in the unpressed reed, the conductor must be conductive to the wiring conductor. Reconnect. When installing wiring terminals, we must ensure that the specifications and models match. After installation, we should check the crimping and installation in time. After the terminal is installed and strengthened, it can be checked by one press, two views and three pull. One pressure is to use the hand to hold the wire on the terminal, two is to check the terminal outside the inspection copper wire, the inner can see copper wire, three pull is to use certain strength (according to the line diameter and specifications of terminal changes) pull wire, require wire can not be loosened.

2. Strengthen the monitoring and control of the cage terminal

At regular intervals, full load test is carried out in the library, and infrared point temperature is used to measure the temperature of the wiring terminal to ensure the heating up of the distribution terminal conforms to the relevant requirements. We should strengthen the monitoring and control of the terminal temperature in the distribution cabinets, and once we find the warming phenomenon, we should take corresponding measures in time to deal with them. To strengthen the daily static inspection of the wiring terminals of the distribution cabinet and to reinforce the terminals at regular intervals, especially the wiring terminals of the main line of the distribution cabinet, the pretightening force should be applied to keep the terminals fastened and the conductors of the wires are in good contact with the terminals.


3. Apply a temperature indicator on the wiring

The temperature indicator is applied at the terminals of the distribution cabinet. When the temperature of the terminal at the terminal of the temperature indicator exceeds the specified temperature (generally 80), the indicator will discolourfully and the discoloration of the indicator is irreversible, so that the abnormal heating of the terminals and electrical components can be found in the initial time, and it can be effective. Prevent burning loss of terminal terminal. Change the distribution cabinet door to partial transparent or full transparent. Once the electrical components or terminals are abnormal heating, smoke can be detected and processed in time. In order to prevent the burn out of terminals of distribution cabinets better, it is possible to turn the reed press connection used in the distribution cabinets of 10mm and above to spiral.


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