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Common Sichuan high voltage cable fault analysis, you may need to

Release time:2021-05-14 Author:admin

Today, I'd like to analyze the common faults of Sichuan high-voltage cable and the causes of these faults, hoping to help you avoid the occurrence of faults and better use cable products.

The common fault types of high voltage cable can be summarized as grounding, short circuit and disconnection, and the fault types mainly include the following aspects:

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1. Flashover fault. The insulation of the cable is in good condition under low voltage and there is no fault. But it only needs the voltage value to rise to a certain scale. After a period of time, if a certain voltage continues to rise, the insulator will break down instantaneously and produce flashover fault.

2. Single phase core broken or multiphase core broken. In the cable conductor connection test, the insulation resistance of each conductor of the cable meets the relevant provisions, but it is found that one or more phases cannot be connected, so it is clear that one phase core wire is broken or multi-phase wire is broken.

3. One or two core wires of three core cable shall be grounded. Test the disconnection of one or two wires of three core cable with insulation megger, and then telemeter the insulation resistance of one or two wires to ground. If the insulation resistance between iron cores is much lower than the normal value, the insulation resistance value is higher than 1000 ohm, which is called high resistance grounding fault; On the contrary, it is a low resistance ground fault. These two kinds of faults are called disconnection and grounding faults.

4. Three phase iron core short circuit. The grounding resistance is the basis to judge the short circuit fault of three-phase core of cable. There are two kinds of short circuit fault: low resistance short circuit fault and high resistance short circuit fault. When the three-phase iron core is short circuited, if the grounding resistance is less than 1000 ohm, it is a low resistance short circuit fault, otherwise it is a high resistance short circuit fault.

The direct cause of cable failure is the breakdown caused by the reduction of insulation, which can be summarized as follows:

1. External force damage. External force damage is a common cause of cable failure. After the cable is damaged by external force, there will be a large-scale power failure. For example, in the process of underground pipeline construction, the traction force of construction machinery is too large, resulting in the cable being broken; The insulation layer and shielding layer of the cable are damaged due to excessive winding of the cable; Excessive cutting and deep knife mark during cable stripping. These direct external forces will certainly damage the cable.

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2. The insulation is damp. Improper cable production process will lead to the rupture of cable protective layer; The sealing performance of cable terminal joint is not good; The cable sheath may be punctured by objects or corroded during cable operation. These are the main reasons for the damp of cable insulation. At this time, the insulation resistance decreases and the current increases, resulting in power failure.

3. Chemical corrosion. A large amount of heat will be generated in the cable insulation when it is electrified for a long time. If the cable insulation works in a harsh chemical environment for a long time, its physical properties will be changed, and the cable insulation will be aged or even lose its function, resulting in power failure.

4. Long term overload operation. Power cables have been operating in high current environment for a long time. If there are impurities in the line insulation, it may be aging, lightning and other external factors on the impact of overvoltage, overload operation will produce a lot of heat, easy to lead to power cable failure.

5. Quality of cables and cable accessories. Cables and related accessories are two important cable materials, and their quality problems directly affect the safe operation of power cables. The production of cable and its accessories and three cables simply presents quality problems. For example, the cable will be affected by moisture due to lax closure during transportation and storage; The insulation pipe is rough with uneven thickness and bubbles in it; It is impossible to peel off the three ends of the prefabricated cable; The planner didn't make the cable joint as required. In addition, improper material selection and poor water resistance in cable product planning will also lead to cable quality problems.

What else do you want to know about Sichuan high voltage cable? Welcome to leave a message or call us, Zhongtian cable will serve you wholeheartedly!