Specification of explosion-proof cable and usage characteristics of explosion-proof cable
At present, with the rapid development of industrial automation in our country, explosion-proof cables are used as power supply equipment for communication, monitoring, detection, alarm and control systems in the production process, explosion-proof safety power supply is mainly used in coal mine, petroleum, chemical industry, textile and coal mine and other containing mixture environment. What kind of cable is called 'explosion-proof cable?
That is, the short circuit or electric spark of the line is not enough to ignite the inflammable and explosive gas around. Such a circuit is called an intrinsic explosion-proof safety circuit, and the cable used is called an 'explosion-proof Cable '.
Explosion-proof cable is characterized by low capacitance, difficult storage of electric charge, good shielding performance and antistatic performance.
Explosion-proof safety power supply circuit must meet the requirements of explosion-proof safety circuit standards. At present, explosion-proof safety products and standards have formed a relatively complete system.
There are many manufacturers of explosion-proof cables, and their quality is uneven. When customers buy explosion-proof cables, they must report to the manufacturer (Cable sales company)
Ask for the drawings, or the use of explosion-proof cable environment, and the detailed description of the occasion, so as to avoid economic losses.
The varieties of explosion-proof cables include IA grade control cables, signal cables, computer cables, coaxial radio frequency cables, etc.
Under normal working conditions, when there is one fault or two faults in the circuit, the explosive gas mixture cannot be ignited.
In IA circuit, the working current is limited to less than 100mA, which is suitable for chemical industry, oil refining, ship, etc.
IB grade: Under normal working conditions and when there is a fault in the circuit, the explosive gas mixture cannot be punctured.
In IB circuit, the working current is limited to less than 150mA, which is suitable for mines and explosion-proof equipment.
Another type of explosion-proof cable is used for coal mine flame retardant explosion-proof cable, must hold the product of mine product safety mark certificate, m grade: Product Coal Mine power cable, coal mine signal cable, coal mine Shearer cable, coal mine steel wire armored cable, coal mine steel wire braided cable, etc. , suitable for coal mine underground, vertical shaft, inclined shaft, shaft, etc.
One of the advantages of the shielding integrated wiring system is that the transmission performance of the core wire is not affected by the surrounding environment, because the shielding layer plays a blocking role, which makes the core wire only electromagnetically coupled with the shielding layer, however, the distributed capacitance between the shielding layer and the external metal objects has nothing to do with the core wire.
In this way, the super six types of shielded twisted pairs only need to install the acceptance criteria of the integrated wiring system (National standard)
The installation can be carried out without considering whether the large metal objects around will affect the twisted pair.