Insulation breakdown of Heat Shrinkable Termination and its analysis

Cable insulation breakdown refers to the fault that the original insulation function of the cable is damaged due to external damage (extrusion, lightning strike, etc.) and aging of insulation materials. The original insulation function is lost, and the core wire-to-core, core to cable outer protective steel belt, and ground discharge of the cable during operation result in a grounding short circuit.

Several phenomena of Heat Shrinkable Cable Termination fire:

1. Bad weather conditions, high air humidity, rain, thunder and lightning.


2. The heat shrink terminal of the cable is 30cm away from the ground wire, and flashover pulling arc discharge leads to spontaneous ignition.


3. Hole-like discharge traces are left in the debris.

Hazards of Heat Shrinkable Cable Termination failure:

1. During the operation of the cable, the insulation breaks down the single-phase ground. Although the power supply is not stopped suddenly, it is necessary to exit the operation.

2. When the local cable burns and generates high temperature, which reaches or exceeds the ignition temperature of the adjacent cable, it will lead to the mass burning of the cable, causing interphase short-circuit protection action, and the main equipment is out of operation due to power failure. Serious will also be connected to the electrical equipment burned down, the formation of a major malignant accident.

Causes of accidents at Heat Shrinkable Cable Termination:

1. Poor operating conditions. The cable terminal runs under high temperature and humidity for a long time and is impacted by external overvoltage (lightning), which will have cumulative damage effect on cable insulation.

2. Poor construction. In the construction process, due to the poor construction, the insulation of cable accessories does not meet the requirements, the waterproof sealing performance of the terminal and the main insulation interface is poor, or the insulation layer of the cable body is damaged, causing the overall insulation reduction.

3. The quality of cable accessories varies greatly from manufacturer to manufacturer. Individual manufacturers use inferior materials, containing more impurities, backward production technology, the production of insulation tube thickness uneven, poor ductility of rubber products. The surface of the insulation tube has spines, punctures, bulges and wrinkles after heating and shrinkage. The cable terminal service life is greatly shortened.

Measures to prevent Heat Shrinkable Cable Termination fire accidents：

1. Strengthen daily inspection and operation analysis. Especially strengthen the inspection of fire-prone cable terminals. If there are any defects that endanger the safe operation of the cable, such as the swelling and breakage of the cable outer sheath, the defects should be eliminated immediately. Avoid fire accidents caused by cable faults.

2. Strengthen the operation skills training of construction personnel. Strict installation process, strengthen the sealing treatment, prevent water intrusion, use sealing waterproof glue, in the joint of the outermost layer of insulation and cable sheath connection, ethylene propylene rubber belt, epoxy resin tape, winding insulation material in addition to the main insulation, also have waterproof sealing function.

3. Use the cable terminal production tool installed. Semiconductor cutters, insulation cutters and LPG flamethrowers for heating can improve the quality of cable terminals.

4. Use heat shrinkable outdoor terminals from reliable manufacturers. The heat shrinkable cable termination products of HUAYI CABLE ACCESSORIES Co.,Ltd. have excellent electrical and mechanical properties, light weight, easy installation, aging resistance, and are widely used in electric power, electronics, petroleum, chemical, construction, communication and other electrical fields.

5. Improve operating conditions. Avoid cables running in high humidity environment for a long time to improve the reliability of lightning arrester devices.