A common fault analysis of high voltage power cables
with the quick arrival of the information age, the level of science and technology unceasing enhancement, high voltage power cable level power supply system has been increasingly widely used. This article will focus on high voltage power cables common problems and the reasons were analyzed, and the details, please see below:
1. Factory production reason
factory production reason according to the different parts, ontology reason is divided into cable, cable connector, cable grounding system reasons.
2。 Design reason
cable swell caused by heating cable crowded injury lead to breakdown. Crosslinking cable load is high, the wire core temperature, heating cable swell, at the top of the tunnel in turning on the cable on the bracket elevation, big load cable operation activities for a long time, great strength to support elevation crushed cable outer sheath, metallic sheath, into cable insulation layer result in cable breakdown.
3。 Make cable ontology reason
general issues in the process of cable produce simple insulation eccentricity, insulation shielding thickness uneven, insulation contains impurities, inner and outer shield has swelled, uneven crosslinking degree of be affected with damp be affected with damp, cable, cable metal sheath seal bad, etc. , in some cases more serious may be completed test, or soon after put into operation in most exist in way of faults in the cable system, to develop a serious risk for cable run safely for a long time.
4。 Cable grounding system
cable grounding system includes cable boxes, cable grounding maintenance box ( With protection layer maintenance) , cable cross interconnection, sheath maintenance device. General first because of the simple problems of box seal owe good water lead to multipoint earthing, causes the metal sheath induced current is too large. Other protective layer maintenance device parameters selection is not reasonable or owe good quality zinc oxide crystals is easy to cause unstable sheath maintenance device damage.
5。 Cable joint production reason
type high voltage cable joint has wrapped around, die casting, molding, such as types, need the production workload is big, and because of the limitation of the condition and reason of the craft that make, insulating tape will inevitably have gap between layers and impurities, so simple problem. Domestic common type of choice is assembled and prepared. Cable joint is divided into cable terminal connector and cable connector, no matter what method of joint, cable joint problems generally appear in the cable insulation shielding fracture place, because here is converged on the part of the electrical stress, due to production reasons cause of cable joint problem have stress cone body making faults, insulation filler, seal oil etc.
6。 Construction quality reason
as construction quality lead to high voltage cable system example of a lot of trouble, primary reason has the following several aspects: one is the condition on site is poor, the cable and connector production in the factory environment and process requirement is very high, and the construction site all owe good control of temperature, humidity and dust. 2 it is cable construction process in the surface of the insulation will inevitably leave minor scratches, semi conductive particles and emery cloth on sand may also be embedded in absolutely, other joint because the insulation is exposed to the air in the construction process, and also are drawn into the moisture in the insulation, all these leave risk to the safety operation for a long time. Three is to install without strict according to the process of construction or rules without considering the possible problems. Four is the completion inspection using dc withstand voltage test form formed the electric field inside the joint result in insulation damage. 5 it is caused by poor sealing treatment. Center joint must adopt copper shell with PE or PVC insulation coating sealing structure, in site construction to ensure the seal is close-grained, so useful to ensure the sealing of joint waterproof performance.
what has been discussed above, at present, the high voltage power cables contains common problem first cable joint poor contact problem and deregulation of power system fault and external causes of trouble, when to deal with these problems, we should follow the principle of analyzing the specific issues, from several aspects to begin to formulate the rational and scientific processing method, and thus on the basis of ensure the normal operation of high voltage power cables, achieve the safety of users.