The phenomenon of wire joint heating is generally manifested in that there is peculiar smell around the wire joint, which can be smelled. This is because the heat of wire joint makes the outer insulation layer smell; Secondly, the ACSR Cables joint is smoking, red, the outer insulation layer is black, fire, or even broken. What are its hazards, causes and countermeasures?
1. Harm
Hot wire connection will not only cause a lot of power loss, but also seriously affect the normal operation of electrical equipment. At least, the working current in the line will increase and the service life of electrical equipment will be shortened. At worst, it will suddenly interrupt the ongoing production, scientific research, medical surgery and other activities, and lead to fire and electric shock accidents, resulting in incalculable losses.
2. Cause
(1) The connector is not tightened during equipment installation and repair. When the current passes through, it may generate heat, even redness, smoke, fire and disconnection. ABC Cables, switches and electrical appliances are connected through wire posts. Due to careless construction, no washer is added on the terminal post and the Gong cap is not tightened, which will also increase the contact resistance. For example, in a hotel, because of this reason, the conductor heated and melted, and the molten beads fell on the cardboard box below, causing a fire.
(2) The connector will also loosen after long-term operation. Some joints are of good quality during installation, but they will become loose due to thermal expansion and cold contraction or long-term vibration. For example, for copper aluminum joints in long-term operation, if there is no silver plating or tin hanging on the contact surface, the contact surface produces serious electrochemical corrosion and generates oxide film, which increases the resistance at the joint and is very easy to become a hot spot.
(3) For contacts with small current, the current increases suddenly due to the sudden change of the system, resulting in contact heating;
(4) In case of short circuit fault of the system, the over-current makes the contact with insufficient capacity or defective contact ignite instantly, etc.
Therefore, the contact heating is mainly caused by the increase of contact resistance.
3. Countermeasures
If the connector is well connected, the heating of the connector is prevented, and the heating problem of the AAAC Cable connector will not appear, so it does not need to be handled. Therefore, the wire joint shall be firm, tight and beautiful without overlap, bending, crack and concave convex; The mechanical strength of the joint shall not be less than 80% of the mechanical strength of the conductor; The insulation strength of the joint shall not be lower than that of the conductor. During installation and maintenance, the joints of wires shall be reduced as much as possible. Conductors with too many joints shall not be used. For joints of movable lines and outdoor lines, special attention shall be paid to the provision that only one joint is allowed between two adjacent wire stems.
