In recent years, the city has developed rapidly
Subway, station, hospital, school, high-rise housing
Expansion of public facilities construction
The number of high-rise buildings has soared
The demand for urban electricity is rising
Such a densely populated focus area
Serious consequences of fire
In recent years, the fire spread trend of such sites presents similar pattern
Analysis of experts in building and safety fire protection
There are still many AAC Cables for public facilities
No fire protection
It is difficult to play an appropriate role in the fire
The law expressly stipulates that the fire protection system needs mineral insulated cable in the code of fire protection design of building engineering to pass the fire inspection and acceptance.
Because mineral insulated ABC Cable can not only ensure the fire power supply within the fire duration (more than 180 minutes), but also will not delay the fire, no smoke and secondary disasters, thus winning valuable time for fire rescue.
It can be said that mineral insulated cable is a special cable used in the fire protection of important national facilities, large public areas, high-rise buildings and other places. Its fire resistance, durability, safety, reliability and economy are irreplaceable by traditional power cables.
1、 Structure form of mineral insulated cable
Chengtiantai mineral insulation cable is a kind of cable which is wrapped with copper sheath and separated from the conductor and sheath with magnesium oxide powder as inorganic insulation material (optional for outer sheath), and forms a close whole with metal core and sheath.
Magnesium oxide is also a kind of non combustible material, and it will not produce toxic smoke or other harmful substances when encountering high temperature. Therefore, the cable with magnesium oxide as the insulator of copper core and copper sheath has better performance and many advantages.
2、 The properties and advantages of mineral insulated cables
Chengtiantai mineral insulation cable mainly includes bbtrz (flexible mineral insulated fire-proof cable) and yttw (flexible inorganic mineral insulation cable), which has good fire resistance, high temperature resistance, high carrying capacity, waterproof, corrosion resistance, mechanical damage, radiation resistance, electromagnetic compatibility, beautiful and generous appearance. At the same time, the cable will not emit any smoke under fire conditions Halogen and toxic and harmful gases.
1. Fire protection performance
Because mineral cables are all made of inorganic materials, they will not cause fire, combustion or combustion supporting, and toxic gas will not be produced. Even if there is fire outside, the cable can still work normally. Mineral insulated cable is made of magnesium oxide as insulator, and the melting point of magnesium oxide is as high as 2800 ℃, which is difficult to burn easily, so the fire resistance of mineral insulated cable is excellent.
The test shows that the mineral insulated cable can be operated normally for 2 hours in a flame with temperature of 800 ℃ -900 ℃; The cable is still intact and continues to operate normally after 30 minutes of combustion under the flame of 1000 ℃.
2. High temperature resistant operation, high load flow
The normal operating temperature of mineral insulated cable can reach 250 ℃, and in special cases, the cable can be maintained in a short time at the temperature close to the melting point of copper sheath. It is very suitable for laying in high temperature places, such as metallurgy, boiler, glass furnace, blast furnace and other environments.
The cut-off flow of MgO powder is far higher than that of other cables. Because magnesia powder has better conductivity coefficient than plastic, the same working temperature and flow rate are larger. For lines with more than 16mm, one section can be reduced, and two sections can be reduced for places where people are not allowed to contact.
3. Waterproof, explosion-proof, high mechanical strength
The insulation layer of mineral insulated cable is processed by high density compaction process, and then protected by seamless copper sheath. In the product standard, it must be subject to three requirements of fire resistance, spray resistance and mechanical impact resistance, which can withstand severe impact and mechanical damage. Therefore, it not only prevents the water, moisture, oil and some chemical substances from being infringed, but also suitable for connecting the explosion-proof equipment and equipment in places with explosion risk.
4. Overload protection
When the line is overloaded, the plastic cable will cause insulation heating or breakdown due to over-current or overvoltage. For mineral insulated cables, as long as the heating temperature of copper is not reached, the cable will not be damaged. Even if the breakdown occurs in a short time, the high temperature of magnesium oxide at the breakdown point will not form carbides. After overload removal, the cable performance will not change and can still be used normally.
5. Long service life, more safe and reliable
Because the structure of mineral insulated cable is composed of copper core and insulating sheath, it is a closed whole, so it is difficult for the material to aging due to the oxygen action in the outside air. This makes the overall service life of the cable longer (2-3 times the life of the ordinary cable), and the copper sheath’s own characteristics make the cable better grounded, Therefore, the lightning protection and grounding measures are effectively implemented, so as to ensure the safety and reliability of the electrical line operation.
Due to the many excellent characteristics of mineral insulated cables, many electrical design codes or standards have been adopted in recent years, and also used in many engineering projects in different industries. It can be expected that the use of mineral insulated cables in China will increase greatly in the next ten years.
