Four Steps for Maintaining Power Cables
Power cable is one of the essential materials for transporting electric energy, and is widely used in economic production. Once a cable fails, it will not only threaten the safe and stable operation of the power grid, but also cause economic losses to the enterprise, and in serious cases, it will cause a chain of destructive reactions. Therefore, how to quickly troubleshoot problems, solve faults, and prevent the occurrence of faults has become a major issue of concern in the current power industry. The following editor will explain the relevant issues in the operation and maintenance of power cables.
1、 Test, acceptance and commissioning of power cables
During the construction process, in addition to conducting handover tests and preventive tests, insulation tests should also be conducted to identify and inspect the cable quality and process quality in all aspects of the construction. Before laying, conduct a test on the cable tray to determine the quality of the cable; After and before laying, test whether the cable is damaged during the laying process; Test the cable head after construction to determine the quality of the cable head; Tests are conducted before and after cable repair to determine the repair quality of the cable. The main contents of the inspection are as follows:
(1) The cables should be arranged neatly, and the fixing and bending radius of the cables should comply with the design drawings and relevant regulations. The cables should be free of mechanical damage, and the signboards should be installed completely, correctly, and clearly. The terminals and intermediate joints of oil immersed paper insulated cables and oil filled cables shall be free of oil leakage;
(2) The cable trench and tunnel shall be free of debris, and the cover plate of the cable trench shall be complete. The lighting, ventilation, drainage, and other facilities in the tunnel shall meet the design requirements;
(3) The sign piles of directly buried cables should conform to the actual path, with the spacing meeting the requirements, and the signs should be clear, firm, and durable;
(4) The signs and night lighting devices on both sides of the underwater cable line and in the anchor prohibition area shall meet the design requirements.
2、 Precautions for cable line operation
(1) Do not overload or overheat for a long time. Therefore, do not neglect the monitoring of cable load current, external temperature, and joint temperature;
(2) Cable line feeder protection should not be put into reclosing. The faults of cable lines are mostly permanent faults. If the reclosing action is taken, it will inevitably expand the accident and threaten the stable operation of the power grid;
(3) After the feeder of the cable line trips, do not ignore the inspection of the cable. Focus on checking whether the cable path is excavated and whether the wires are damaged. If necessary, further inspection and judgment should be conducted through testing;
(4) Special attention should be paid when inspecting the operation of directly buried cables: the ground near the cable path cannot be arbitrarily excavated; Heavy objects, corrosive substances, and temporary buildings are not allowed to scale on the ground near the cable path; Cable route marker posts and protective facilities cannot be moved or removed arbitrarily;
(5) The cable line must be retested before it can be put into use when resuming operation after being deactivated.
3、 Sidetracking of cable faults
After a cable failure, the general side search steps are as follows:
(1) Determine the nature of the fault: Based on the phenomenon that occurs when the fault occurs and some simple tests, preliminarily determine the nature of the fault, and determine whether the fault resistance is high or low, whether it is a flashover or closed fault, whether it is a short circuit to ground, a broken wire, or a mixture of them, and whether it is a single-phase, two-phase, or three-phase fault.
(2) Burnthrough of fault points: that is, turning a high resistance fault or flashover fault into a low resistance fault through burnthrough for rough measurement;
(3) Rough measurement: use an instrument to measure the fault distance on one side of the cable, and calculate the location of the fault point using the technical data of the cable line;
(4) Accurate measurement point of fault point: Determine the precise location of the fault point through methods such as impulse discharge acoustic measurement, audio frequency induction method, and acoustic magnetic synchronous detection method.
4、 Operation and maintenance of cable lines
The operation and maintenance of cable lines involves three important tasks: load monitoring, cable metal jacket corrosion monitoring, and insulation supervision. The main items include: conducting cable line inspection, cable preventive testing, preventing external damage to the cable, analyzing the cause of cable faults, cable fault detection, and wire fault repair. If the cable is damaged, it is necessary to thoroughly eliminate the cause of the fault before repairing or replacing the cable.
W: www.winwinpipe.com
M: rosie.lu@winwinpipe.com
Post time: Mar-24-2023