Cable line fault according to the classification of fault liability
( 1) Staff negligence
cable improper selection, cable head structure design mistakes, improper operation, maintenance, etc.
( 2) Equipment defect
cable manufacturing flaws, cable head accessory material, using the legacy of the old equipment defect, improper installation or construction technology causes such as cable head bad quality defects.
( 3) Natural disasters
a lightning strike, flood, typhoon, birds, insects, debris flow, ground sink, earthquake, falling body, etc.
( 4) Normal aging
general cable run more than 30 years of insulation aging, outdoor head running more than 20 years of tide and vertical laying of oil immersed paper insulated cable in more than 20 years of high-end dry, etc.
( 5) External force damage, corrosion, user error, and trial of new products, new technologies, etc.
( 6) High impedance fault
high resistance grounding or short circuit fault. A core or several core over the ground cable insulation resistance between or core and core insulation resistance is lower than normal, and effectively at all conductor continuity called high resistance fault. General common high impedance fault are single phase grounding, two phase short circuit or grounding, etc.
( 7) Bolt failure
each cable core insulation is good, but there is one core or several core conductor discontinuous called single-line breakdown.
( 8) Bolt and grounding or short circuit fault
a core or several core cable conductor of discontinuity, after ( High or low) Resistance grounding or short circuit called break line and grounding or short circuit fault.
( 9) Leakage fault
leakage fault is an extreme form of high resistance fault. In the cable insulation preventive withstand voltage test, the leakage current increases with the increase of test voltage and, until more than value of leakage current ( The test voltage is not yet or has reached the rated test voltage) , this kind of high impedance fault is called the leakage fault. Leakage fault may be high insulation resistance, and even reach the qualified standard.
( 10) Flashover fault
flashover fault is high resistance fault is an extreme form. For cable insulation preventive withstand voltage test, the leakage current small and smooth. But when the test voltage to a value ( Not yet or has reached the rated test voltage) , the leakage current increases suddenly and quickly, flashover breakdown, this high impedance fault is called flashover fault. Flashover failure of the insulation resistance is extremely high, usually above the eligibility criteria. Has the flashover fault cable, in the short term, under the low voltage ( No greater than flashover breakdown voltage) And the breakdown of flashover phenomenon can be completely stop and show better electrical performance.