Ordinary cables, we all already know something. So about the mineral insulated cable do not know how many people understand it. Today ZMS cable editor will take you to understand what is mineral insulated cable.
Mineral Insulated Cable Definition
Mineral insulated cable, a copper sheath wrapped copper conductor core.
And magnesium oxide powder is an inorganic insulation material to isolate the conductor and the sheath of the cable, the outermost layer can be selected as required to protect the appropriate jacket. Commonly known as MICC or MI cable.
There is a similar cable with metal instead of copper sheath wrapped core and insulation material, known as mineral insulated metal sheathed cable.
Mineral Insulated Cable Development
MI cable originated in Switzerland in 1896, spread to France in 1934, and began to develop in the United Kingdom and the United States in 1936.
It is widely used due to its excellent fireproof characteristics.
The structure can be divided into rigid and flexible two.
The standard can be divided into the national standard cable (rigid) and enterprise standard cable (flexible).
Rigid mineral cable has the old national standard, as the name implies, and is extremely difficult to bend. Transport and installation have great limitations.
Flexible mineral cable RTTZ class has a national standard GB/T 34926-2017. the rest of the models have their standards, the standard of each manufacturer varies from high to low, and the quality varies.
JGJ232-2011 Mineral Insulated Cable Laying Technical Specification, Article 2.0.1 states: that mineral insulated cable is a cable with ordinary annealed copper as the conductor, dense magnesium oxide as the insulation material, and ordinary annealed copper or copper alloy material as the sheath.
Classification of Mineral Insulated Cable
Except for the national standard cable, all other flexible mineral cables are enterprise standard.
Relatively speaking, the national standard cable has a high process, and the construction is complicated and rigorous.
Because the metal sheath itself is extremely difficult to bend, the installation is the most difficult. And the need for expensive special accessories, fire performance is also the highest BS6387.
And flexible cable installation is similar to ordinary cable, the construction threshold is low.
But the same fire performance to BS6387, the application of the main according to the building fire rating, and the importance of the selection of matching products.
Rigid mineral cable by the process limitations can not be longer production, and installation using special accessories.
And bending radius installation using special tools such as baking guns, and bending wheels can reach 6D.
The flexible mineral cable can be produced continuously. With different metal sheath structures and different bending performances, the domestic process is mainly copper, aluminum, cross-welded corrugated copper, and interlocking armored metal sheath. Allowable bending radius in decreasing order, the minimum only to 7D.
Design and construction should consider the actual site, cable bridge restrictions, and the choice of appropriate products.
In general, the smaller the allowable bending radius, the less difficult it is to install.
The rigid mineral cable itself is relatively hard, the same impact resistance is also very strong.
A flexible mineral cable is more flexible, impact resistance depends on the specific structural components of the corresponding cable.
However, all mineral cables except the interlocking armored type are difficult to lay through curved pipes, especially large-size cables.
Advantages of Mineral Insulated Cable
Since all the materials of this cable are made of inorganic materials, it has some advantages that other cables may not have.
1 Fire Resistance
The two materials used in mineral-insulated cables, copper and mineral insulation, are inorganic.
This cable will not burn and will not contribute to ignition, and can continue to operate under conditions close to the flame.
The copper sheath melts at 1083°C.
2 High Operating Temperature
The mineral-insulated cable can withstand continuous operating temperatures up to 250℃.
And, in an emergency, the cable can continue to operate for a short period at a temperature close to the melting point of the copper sheath.
3 Long Life
The inorganic materials applied in a mineral-insulated cable can ensure the stability, long life, and fire resistance of the cable.
The highly compacted insulation material in mineral-insulated cables prevents the passage of steam, gas, and flame between the parts of the equipment connected to the cable.
5 Small Outer Diameter
The diameter of mineral-insulated cables is smaller than other cables with the same rated current.
If the mineral-insulated cable is completely immersed in water, the mineral-insulated cable can continue to operate with the help of its seamless metal sheath.
7 High Mechanical Strength
Mineral insulated cables are strong and durable and can withstand severe mechanical damage without damaging their electrical properties.
8 High Load Capacity
For the same cross-section of the cable, mineral insulated cable than other types of cable transmission of higher current.
At the same time, mineral-insulated cables can also withstand considerable overload.
9 Short-Circuit Fault Rating
At the same temperature, the short-circuit fault rating of mineral-insulated cables is significantly higher than other types of cables.
Mineral Insulated Cable Product Characteristics
As the cable is all composed of inorganic materials.
It does not cause fire itself, it is not possible to burn or fuel combustion.
As the melting point of copper is 1083℃, the mineral insulation layer is also above the 1000℃ melting point.
Therefore this kind of cable can continue to maintain the power supply in the case of fire close to the melting point of copper, which is a true sense of fireproof cable.
2 High Load Capacity Waterproof
As the actual normal use temperature of mineral insulated cable can reach 250℃.
IEC60702 stipulates that the continuous working temperature of mineral insulated cable is 105℃, which is necessary to take into account the terminal sealing material and safety.
Even so, it still has a far higher load capacity than other cables.
Because mineral type insulation has better thermal conductivity than plastic, so the same operating temperature, the load capacity is greater.
3 Explosion-Proof and Corrosion-Resistant
3.1 Explosion-Proof Characteristics
Since mineral-insulated cables use a metal sheath as a protective layer, flammable gases, oil vapor, and flames cannot reach the electrical equipment connected to the cable, so the cable has explosion-proof characteristics.
3.2 Corrosion Resistance
Since copper has good corrosion resistance, it does not require any additional protection in normal use environments.
In special environmental conditions, such as in environments with strong corrosive effects on copper.
A PVC outer sheath is added outside the cable, so the cable has good corrosion resistance.
4 Other Features
4.1 Damage Resistance
Since the metal sheath of the cable has certain strength and toughness.
So the cable suffers from bending, flattening, twisting and other deformations and the relative positions between the cores and between the cores and sheaths remain unchanged.
This will not produce a short circuit, and will not affect the electrical performance.
4.2 Long Life
As the materials used in the cable are all inorganic, they do not age.
Its service life can be calculated according to the rate of oxidation and corrosion of the copper sheath.
Data show that the sheath oxidation of 0 .25mm, at an ambient temperature of 250 ℃ need 257 years. The sheath thickness of mineral insulated cable is generally between 0.34-1.05, and the use temperature is lower than 250 ℃.
So the cable has the characteristics of long life.
4.3 Halogen-Free and Non-Toxic
Because the cable is composed of all inorganic materials.
Therefore, even at a high temperature of 1000 ℃ burning will not produce smoke halogen and toxic gas is truly halogen-free non-toxic cable.
Applications of Mineral Insulated Cable
Mineral insulated cables have been widely used in many fields.
1 High-Rise Building
General lighting, emergency lighting, fire alarm, fire protection electrical lines, emergency elevator and lift equipment lines, computer room control lines, trunk \ sub trunk distribution system lines, and dual power supply control lines.
2 Oil Platform
General lighting, emergency lighting, potentially dangerous explosive area lines.
3 Warships and Ships
Generator room transmission lines, fire monitoring systems, fire alarm systems, smoke emission, and ventilation lines, galley power lines, and large power lines.
Lines, dual power control lines, emergency lighting, emergency broadcast lines, and computer room control lines.
4 Chemical Industry
General lighting, emergency lighting, potentially dangerous explosive lines, and other places.
5 Subway Tunnel
General lighting, emergency lighting, fire monitoring systems, fire electrical lines, smoke emission, and ventilation lines.
6 Iron and Steel Metallurgy
High-temperature environment power and control lines, emergency power, large power lines, power supply lines that cannot be disconnected, and generator room transmission lines.
7 Power Plant
Large power lines, general lighting, emergency lighting, fire alarm, fire protection electrical wiring.
General lighting, emergency lighting, computer room control lines, large power lines, high-temperature environment power, and control lines, and potentially hazardous explosive area lines.
The above is the introduction of the information brought to you by the editor. ZMS cable company is committed to providing a variety of high-quality cables, for the product has a strict manual qualification audit. High professionalism in cable manufacturing and trustworthy products.