BTTZ insulated cable fireproof cable magnesium oxide cable

Product details
A brief description of mineral insulated cables
Mineral insulated cables are also called fireproof cables or copper core copper sheathed magnesium oxide insulated cables in China, and are simply called cables abroad. This cable was first developed and patented by the Swiss in 2000, and France took the lead in converting this new technology into production in 2005. The emergence of mineral insulated cables is an innovation to traditional cables, especially its role in some important places and key electrical lines, making plastic cables unmatched. Therefore, industrially developed countries such as the United Kingdom, Australia, and Canada have successively begun to produce mineral insulated cables, but they are mainly used only in the construction industry and important industrial facilities. China was relatively late in getting involved, and it was not until 2000 that the Shanghai Cable Research Institute began to develop this product. Due to the particularity of the materials and structure of this product, it has electrical properties, mechanical properties, environmental resistance and environmental protection properties that are unmatched by traditional organic insulated cables. As this product continues to be promoted, people have higher and higher safety requirements, and mineral insulated cables are becoming more and more recognized by people, and are now widely used in basic industry and civil construction.
2 Cable design, ordering model and representation method
Note that cables with a cross-section of ? or above are composed of single-core cables.
Light and heavy
Expression method
Example 1, cross-section is a light copper core, copper sheathed mineral insulated cable, expressed as
Example 2, cross-section is, heavy copper core, copper sheathed mineral insulation The cable is expressed as an example
The cross-section is a heavy-duty copper core copper sheath anti-corrosion jacket mineral insulated cable is expressed as
Three mineral insulated cable structure
Mineral insulated cable with high conductivity copper conductor mineral oxidation Magnesium insulated seamless copper tube sheath is the basic structure. When the cable is used in situations where copper is corrosive, a plastic jacket can be added to the outermost layer.
The continuous working temperature of the bare cable can reach ℃, and it can sustain power supply for hours at ℃. It can be close to the melting point of copper in a short or extraordinary period. The melting point of working magnesium oxide is ℃.
Four main properties of cables
Fire resistance
Cables not only cannot burn themselves, but also will not cause fire. Even in the event of a fire, the cable will still work. And as long as the flame temperature is lower than the melting point of copper, after the fire is eliminated, the cable does not need to be replaced and can still be used. The replacement sheath and core wire materials are more fire-resistant and can be used in oil and gas environments.
Strong overload protection ability
When the line is overloaded, plastic cables will cause insulation heating, aging or breakdown due to overcurrent or overvoltage. For mineral insulated cables, as long as the heat does not reach the melting point of copper, the cable Will not be damaged. Even if there is an instant breakdown, the magnesium oxide at the breakdown point will still be magnesium oxide even if it melts. After the overload is eliminated, the cable performance will not change and it can continue to be used normally.
Large current carrying capacity
Due to the particularity of the cable insulation material and structure, mineral insulated cables have a large current carrying capacity. To transmit the same amount of current, if mineral insulated cables are used, the cross-section can be reduced to a level or larger than that of plastic cables.
High operating temperature
Since the melting point temperature of the insulating layer of magnesium oxide is much higher than the melting point temperature of copper, the maximum normal operating temperature of the bare cable can reach ℃, and it can continue to operate at a temperature close to the melting point temperature of copper in the short term. .
Waterproof, anti-corrosion and explosion-proof
Because the cable is sheathed with seamless copper tubes, the conductor insulation and sheath are densely compacted entities. Therefore, it not only prevents the damage of water, moisture, gas, oil and some chemical substances, but also prevents the spread of flammable oil, steam, gas and flame.
Excellent shielding performance
Cable copper sheath is the best shielding protective layer, which can not only prevent the cable itself from interfering with other cables, but also prevent external electromagnetic fields from interfering with itself.
Strong radiation resistance
Since the materials of the cable are all inorganic, the electrical and mechanical properties of the cable will not change after being exposed to nuclear radiation.
Long service life
Because the cable is composed of inorganic materials, it will not age and its service life is at least hundreds of years.
Environmental protection and safety
The cable components are all inorganic and do not contain any organic matter. Therefore, even if the cable is heated above ℃, it will not produce any smoke, and it will not contain halogen and toxic gases. This cable is a safe product that can truly achieve green environmental protection and no secondary disasters.
High mechanical strength
The cable structure is dense, strong and durable, and can withstand external extrusion, impact, bending and flattening. When the cable is flattened to the original outer diameter of the cable, it can still continue to be used safely and normally.
Bending performance
After the cable is fully annealed, it has bendability that is unmatched by ordinary plastic cables. The minimum bending radius is only times the outer diameter of the cable. If bending needs to be repeated multiple times, a blowtorch is required to heat the bent part to avoid cable rupture. Good grounding Compared with organic cables, it can save one ground wire.
Cables should be conditioned in flames
Whether it is in a factory or a building, the safety of electrical lines is crucial. According to statistics from relevant national departments, among the causes of fires, fires caused by electrical appliances account for the majority. Fires caused by cables account for more than half of electrical fires. Therefore, it is required that the cable not only has the ability to resist external flame damage, but also has the characteristics of not generating and spreading fire sources to prevent aging. Since the materials of mineral insulated cables are all inorganic, the magnesium oxide insulator will not age, and the lines made of it will not cause the occurrence and spread of fire. If a fire is caused by other reasons, the cable will not only be tested by the raging fire, but will also be continuously impacted by other falling objects and sprayed by fire hose water. At this time, while the cable does not produce smoke and toxic gases, it can also ensure the normal start-up of fire-fighting equipment, extinguish the fire and the evacuation of personnel, which is the key to evaluating the fire resistance of the line.
Five cable fire resistance
Fire resistance test method
Cable fire resistance
From the above content, only the cable fire safety performance requirements of the British Metro Company are the requirements for cable fire resistance The real test of fire resistance performance. Because the cable is not free from external interference during the fire, it will be constantly impacted by fire water and fire debris and other heavy objects, and it is on the same line. The fire resistance of organic plastic cables is achieved by the mica tape between the conductor and insulation. Once the plastic fire-resistant cable is burned, the mica and insulation will form a hard shell and a carbon shell respectively. The carbon shell will conduct electricity when exposed to fire water, and the mica hard shell will fall off when exposed to water or other heavy objects. The Sichuan Fire Protection Research Institute and the British Fire Protection Research Institute conducted simulated physical fire comparison tests on mineral insulated cables and plastic fire-resistant cables. The tests proved that only mineral insulated cables can meet the fire resistance safety requirements of the British Metro Company.
Six cable overload resistance
Test conditions: Different types of cables with the same rated current carrying capacity are selected for the test. All test cables are connected in parallel, and the test cables are connected to the adjustable transformer at the same time.
The test method gradually increases the output voltage of the current transformer, thereby changing the current passing through the cable under test, until the current is overloaded and the condition of the cable is observed. Test Conclusion From the test renderings below, it can be seen that after overcurrent is applied to the cable, some of the cables during the test will convert electrical energy into heat energy, causing the cable itself to generate a fire source. It can also be concluded from the test results that only mineral insulated cables will not cause electrical failures due to overload, let alone fires.
Cable overload test
Price and cost-effectiveness of seven mineral insulated cables
Performance comparison
Price comparison in the same use environment The cables all transmit the same carrying capacity Mineral insulated cable copper sheath Replaces ground core.
Comparison conclusion
The cable has a long service life and can avoid secondary investment in the project due to the service life of the plastic cable.
The outer diameter of the cable is small, which saves a lot of wiring space than plastic cables and is easier to design and install.
The cable laying method is simple and can be laid openly without passing through pipes, which can further save project costs.
The cable is resistant to high temperatures, is explosion-proof, corrosion-resistant, waterproof, anti-magnetic and resistant to mechanical damage, including animal bites, will not age, has a large current carrying capacity and strong overload capacity. Any one of these properties is far better than that of plastic cables.
This cable is a true green safety product.
Compared with the current most environmentally friendly halogen-free low-smoke plastic cables, mineral insulated cables not only have greatly improved electrical and mechanical properties, but also truly achieve halogen-free, smoke-free and non-toxic, completely eliminating the need for halogen-free. Toxins remaining in low-smoke plastic cables.
This cable is no longer primarily used in fire protection systems.
Due to its superior performance-price ratio, it has become the development direction to replace non-solid low-smoke cables, fire-resistant cables, and flame-retardant cable bus ducts with a capacity of up to and below.
The performance-price ratio of this product is far superior to any other cable.
Eight Application Design Precautions
Compared with ordinary plastic cables, mineral insulated cables have simpler wiring methods, occupy less space, and have more diverse laying methods, but the models are different.
When the cable is laid in a building space and has aesthetic requirements, it should be designed to be bare. The jacket can also be made of different colors of plastic or halogen-free low-smoke materials according to the requirements of the occasion.
Cables with ammonia and ammonia gas or other environments that are corrosive to copper should be designed with a plastic outer sheath.
Cables with plastic jackets can be laid together with other plastic cables in the same bridge, cable trench, cable tunnel or in places accessible to people, but the bare cable should be laid separately, otherwise it will affect other plastic and other organic cables.
Cables do not need to be put through metal tubes. Single-core cables are not allowed to be put through tubes alone. On special occasions, metal tubes must be put through the lines. Single-core cables must be tightened in each group of circuits before being put through tubes, and they should be designed to have a plastic outer sheath. Set of cables.
Due to the large current-carrying capacity of this cable, it is recommended to increase the design and selection of one cross-section grade. If it is ? and above, it can be used to increase the cross-section grade by two.
Since the copper sheath of this cable can be used as a ground wire, it is recommended to use four-core mineral insulated cables for three-phase five-wire lines.
When considering that the entire line needs to reduce the use of intermediate connections, multi-core cables with a cross-section of ? Small-sized single-core cables can be connected in double or multiple splices, which can double the length of the cable.
When a certain line path is long, and there are parts of the entire line that require mineral insulated cables and ordinary plastic cables, they can be converted through a transfer box.
Cables can be branched from branch boxes with mineral insulated cables