Cable blowout refers to the short-circuit and explosion of a cable during operation.
1. Insulation-Related Causes
|
Cause Type |
Specific Manifestations |
|---|---|
|
Insulation Quality Defects |
Substandard insulating sheaths used during production; defects such as particles, impurities, or bubbles in the insulation layer. |
|
Insulation Aging |
Long-term neglect of maintenance leads to aging and drying of insulation materials, resulting in loss of insulation and mechanical properties. |
|
Insulation Moisture Ingress |
Dampness or water ingress into the cable, leading to reduced insulation performance and causing short circuits. |
2. Conductor-Related Causes
|
Cause Type |
Specific Manifestations |
|---|---|
|
Substandard Conductor Quality |
High impurity content in the conductor, generating excessive heat during prolonged energization and leading to blowout. |
|
Poor Conductor Connection |
Loose crimping or poor welding of intermediate joints, causing oxidation and overheating at the connection points. |
|
Three-Phase Short Circuit Fault |
Short circuit between the three-phase core conductors inside the cable or between a phase and the cable sheath, generating intense heat. |
3. External Force and Construction-Related Causes
|
Cause Type |
Specific Manifestations |
|---|---|
|
Mechanical External Damage |
Physical damage to the cable during installation or operation, resulting in damage to the protective sheath. |
|
Insufficient Bending Radius |
Excessive bending of the cable with too small a radius, causing internal damage. |
|
Non-standard Construction Practices |
Secondary construction causing physical damage to the cable, with rainwater infiltration leading to water ingress. |
|
Improper Wiring Operations |
Irregular wiring practices by operators, leading to blowouts at connection points. |
4. Operation and Maintenance-Related Causes
|
Cause Type |
Specific Manifestations |
|---|---|
|
Overload Operation |
Prolonged overload operation of the cable, causing insulation material temperatures to exceed allowable limits and accelerating aging. |
|
DC Resistance Testing Issues |
Residual charges from incomplete ion release after testing, leading to faults. |
|
Oil Leakage in Oil-Immersed Cables |
Oil leakage due to significant installation height differences, causing the upper section to dry out and pressure to accumulate in the lower section. |
|
Poor Sealing of Junction Boxes |
Air pockets or moisture ingress in intermediate junction boxes, along with substandard insulating agents. |
5. Environmental and Other Causes
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Moisture accumulation and contamination on the surface of cable terminations, cracks in porcelain bushings, and insufficient phase-to-phase distance of lead wires leading to flashover.
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External heat sources: such as welding sparks, baking from high-temperature steam pipes, acid or alkali corrosion, etc.
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Fire spread from adjacent equipment: such as oil circuit breaker explosions, boiler system fires, etc.
Preventive Recommendations
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Strict Quality Control: Use qualified cables and avoid non-standard products.
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Standardized Construction and Installation: Ensure proper bending radius and implement waterproof and moisture-proof measures.
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Regular Inspection and Maintenance: Promptly identify issues such as aging, moisture ingress, and physical damage.
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Load Current Control: Avoid prolonged overload operation.
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Proper Joint Handling: Ensure secure crimping and effective sealing of intermediate joints.
Summary:
Cable blowout incidents can range from causing power outages and equipment damage to posing serious risks to personal safety. Once such an incident occurs, it is essential to thoroughly investigate the cause and eliminate potential hazards to prevent recurrence.
