Mineral insulated cable

Mineral insulated cable is a kind of cable that uses copper sheath to wrap the copper conductor core and magnesium oxide powder as inorganic insulating material to isolate the conductor and sheath. The outermost layer can be selected as appropriate protective sheath. Commonly known as MICC or MI cable. There is a similar cable that uses metal to replace copper sheath to wrap the core wire and insulating material, which is called mineral insulated metal sheath cable.

Classification of mineral insulated cables

Except for the national standard cable (rigid), all other flexible mineral cables are enterprise standards. Relatively speaking, the national standard cable has high technology and complex and rigorous construction. Because the metal sheath itself is extremely difficult to bend, it is the most difficult to install, and it requires expensive special accessories, and the highest fire resistance is BS6387; The installation of flexible cables is similar to that of ordinary cables. The construction threshold is low, but the fire protection performance also reaches BS6387. During the application, matching products are mainly selected according to the building fire protection grade and importance. Rigid mineral cable can not be produced for a long time due to process constraints, and special accessories can be used for installation, and the bending radius can reach (6D) when using special tools such as baking gun and bending runner. Flexible mineral cables can be produced continuously, and different metal sheath structures have different bending properties. Domestic processes mainly include copper pipe (rigid), aluminum pipe, transverse welded corrugated copper pipe, and interlocking armored metal sheath. The allowable bending radius decreases in turn, and the minimum is only 7D (D is the outer diameter of the cable, and the bending radius of ordinary cable is about 10D). In terms of design and construction, the actual site and cable bridge limitations should be considered, and appropriate products should be selected. Generally speaking, the smaller the allowable bending radius, the less difficult the installation is. The rigid mineral cable itself is relatively hard, and the impact resistance is also very strong. Flexible mineral cable is relatively flexible, and its impact resistance depends on the specific structure of the corresponding cable. All mineral cables except interlocking armored type are difficult to bend and run through the pipeline, especially large size cables.

Advantages of mineral insulated cable

Because all materials of this cable are inorganic materials, it has some advantages that other cables cannot have. 1. Fire resistance. Copper and mineral insulation, the two materials used in mineral insulated cables, are inorganic. This kind of cable will neither burn nor support combustion, and can continue to operate under the condition of close to flame. The copper sheath melts at 1083 ℃. 2. High operating temperature. Mineral insulated cable can withstand continuous operation temperature up to 250 ℃. Moreover, in case of emergency, the cable can continue to operate for a short time at a temperature close to the melting point of the copper sheath. 3. Long service life. Inorganic materials used in mineral insulated cables can ensure the stability, long service life and fire resistance of cables. 4. Explosion-proof. Highly compacted insulating materials in mineral insulated cables can prevent the passage of steam, gas and flame between equipment parts connected with cables. 5. Small outer diameter. The diameter of mineral insulated cable is smaller than that of other cables with the same rated current. 6. Waterproof. If the mineral-insulated cable is completely immersed in water, with the help of its seamless metal sheath, the mineral-insulated cable can continue to operate. 7. High mechanical strength. Mineral insulated cables are durable and can withstand severe mechanical damage without damaging their electrical properties. 8. Large carrying capacity. For cables with the same cross section, mineral insulated cables transmit higher current than other types of cables. 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 that of other types of cables.