Coal Mine Cable Faults and Troubleshooting (1) Cable Short-circuit Faults For armored cables, the causes of cable short-circuit faults are:
(1) In the manufacture of cable heads, short-circuit accidents often occur at the trifurcate point of the cable head due to damage to the trifurcation or improper insulation treatment and the process does not meet quality requirements. In order to prevent accidents at the site, when manufacturing cable heads, the process of making cable heads must be followed. Special attention must be paid to handling the insulation of the three-forked outlets, and moisture should not be allowed to enter the trifurcation to destroy its insulation.
(2) Cracks in strips of cable armored steel, cracks in lead-packs, and thus ingress of moisture, causing insulation breakdown and short circuit accidents. One of the common reasons is that the radius of cable bending is too small during handling or laying. In order to prevent accidents, special attention should be paid to the bending radius of the cable during the handling and laying process.
(3) The cable is short-circuited due to collision, extrusion, etc. due to roof fall, or mine car falling off the road. If the cable is properly laid and suspended, this accident can be avoided.
(4) Long-term inventory or unused cables. The two ends of the cable are not sealed. When the cable head is manufactured, the length of the already wetted part is not cut off or cut off, resulting in a short circuit. The preventive measure is to seal the two ends when the stock cable is not used for a long time; when making the cable head, a section of cable must be cut off and a withstand voltage test must be done.
For rubber-jacketed cables, the main cause of short-circuit faults is mechanical damage. Such as: planing, blasting, falling roof, collision, crowding and other direct causes short-circuit between the phases. Too long to use, insulation aging is one of the reasons. Similarly, if the cable hanging is done according to the requirements, this accident can be avoided.
(2) Cable leakage faults One phase of leakage of the mining cable is ground fault, which is a common failure of low-voltage cables in the underground. Because the cable is used in a humid environment, it is easy to cause the insulation resistance to drop to a dangerous value and ground leakage; and the cable is damaged by mechanical damage to cause a phase of insulation; the cable and the connector of the device collide with the shell, and the thread head is disconnected and connected to the shell;
Poor thermal compensation of the cable causes a phase leakage earth; in addition there are chicken paws, sheep tails, and connectors in the cable connection, which are the direct cause of cable leakage grounding.
(3) Failure of the cable breakage fault The entire cable is broken because the cable is scraped by the wire rope of the small winch or the object it pulls, or it is scratched by the chain plate of the scraper conveyor or the like. The causes of these failures are illegal operations, improper maintenance, and insufficient mechanical strength when selecting cable sections.
(D) cable ignition cable fire accident, the reason is the occurrence of phase short-circuit fault, the fuse, over-current relay and other protection failure, a strong short-circuit current high temperature ignites the rubber sheath rubber cable, causing fire. Preventive measures: First, strengthen cable maintenance. The second is to strengthen the management of over-current protection; the third is to use flame-retardant cables.
The most fundamental reason for preventing cable faults is to prevent the cable from being overloaded and from damaging human factors during use.
(1) In the manufacture of cable heads, short-circuit accidents often occur at the trifurcate point of the cable head due to damage to the trifurcation or improper insulation treatment and the process does not meet quality requirements. In order to prevent accidents at the site, when manufacturing cable heads, the process of making cable heads must be followed. Special attention must be paid to handling the insulation of the three-forked outlets, and moisture should not be allowed to enter the trifurcation to destroy its insulation.
(2) Cracks in strips of cable armored steel, cracks in lead-packs, and thus ingress of moisture, causing insulation breakdown and short circuit accidents. One of the common reasons is that the radius of cable bending is too small during handling or laying. In order to prevent accidents, special attention should be paid to the bending radius of the cable during the handling and laying process.
(3) The cable is short-circuited due to collision, extrusion, etc. due to roof fall, or mine car falling off the road. If the cable is properly laid and suspended, this accident can be avoided.
(4) Long-term inventory or unused cables. The two ends of the cable are not sealed. When the cable head is manufactured, the length of the already wetted part is not cut off or cut off, resulting in a short circuit. The preventive measure is to seal the two ends when the stock cable is not used for a long time; when making the cable head, a section of cable must be cut off and a withstand voltage test must be done.
For rubber-jacketed cables, the main cause of short-circuit faults is mechanical damage. Such as: planing, blasting, falling roof, collision, crowding and other direct causes short-circuit between the phases. Too long to use, insulation aging is one of the reasons. Similarly, if the cable hanging is done according to the requirements, this accident can be avoided.
(2) Cable leakage faults One phase of leakage of the mining cable is ground fault, which is a common failure of low-voltage cables in the underground. Because the cable is used in a humid environment, it is easy to cause the insulation resistance to drop to a dangerous value and ground leakage; and the cable is damaged by mechanical damage to cause a phase of insulation; the cable and the connector of the device collide with the shell, and the thread head is disconnected and connected to the shell;
Poor thermal compensation of the cable causes a phase leakage earth; in addition there are chicken paws, sheep tails, and connectors in the cable connection, which are the direct cause of cable leakage grounding.
(3) Failure of the cable breakage fault The entire cable is broken because the cable is scraped by the wire rope of the small winch or the object it pulls, or it is scratched by the chain plate of the scraper conveyor or the like. The causes of these failures are illegal operations, improper maintenance, and insufficient mechanical strength when selecting cable sections.
(D) cable ignition cable fire accident, the reason is the occurrence of phase short-circuit fault, the fuse, over-current relay and other protection failure, a strong short-circuit current high temperature ignites the rubber sheath rubber cable, causing fire. Preventive measures: First, strengthen cable maintenance. The second is to strengthen the management of over-current protection; the third is to use flame-retardant cables.
The most fundamental reason for preventing cable faults is to prevent the cable from being overloaded and from damaging human factors during use.
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