Mineral insulated cable
date：Apr 20th,2024
Mineral insulated cable is a kind of inorganic material cable. The outer layer of the cable is a seamless copper sheath, and between the sheath and the metal core is a tightly compacted magnesium oxide insulation layer. Mineral insulated cables are divided into distribution cables, heating cables and heating elements, thermocouple cables and compensation cables, special cables and so on. Here is a detailed introduction to mineral insulated cables.
Characteristics of mineral insulated cable:
1. Security
Mineral insulated cables are made of copper and magnesium oxide. The melting point of copper is 1083 ° C, and the melting point of magnesium oxide is 2800 ° C. Therefore, when its temperature does not exceed 1000 ° C, the cable structure will not have problems. Therefore, in most places, it will not be dissolved by melting or burning, and it will not spread fire. Mineral insulated cable insulation layer is made of inorganic material, it will not emit any smoke and harmful gases, and in contrast, traditional cables (including flame retardant, low smoke and low halogen, low smoke and no halogen and its corresponding refractory cables) in the fire, fire or long-term overload insulation damage when smoke and harmful gases will be in.
2. Fire resistance
At present, the commonly used PVC cable (ordinary type, flame retardant type, refractory type, etc.) has a maximum service temperature of 70 ° C, beyond which the aging of the insulation layer is accelerated, the life is shortened, and then the fire is caused. According to the British BS6387 cable fire resistance test standard, only mineral insulated cables can meet the following three tests: A: open flame burning 950℃, lasting 3 hours, B: open flame burning 650℃, spraying water lasting 15 minutes, C: Open flame burning 950℃, every 30 seconds with heavy impact, while the domestic fire-resistant cable (NH-VV) can only meet the GB12666.6-90 fire test in the class A test: open flame burning 950℃, lasting 90 minutes. The fire-resistant cables produced by most manufacturers can only meet the class B test; An open flame burns at 750 ° C for 90 minutes.
3. Large carrying capacity
Because mineral insulated cable normal use temperature can reach 250℃. IEC60702 stipulates that the continuous operating temperature of mineral insulated cables is 105 ° C. This is to take into account the terminal sealing materials and safety needs, even so, its interception is far more than other cables, because magnesium oxide powder has a better conductor coefficient than plastic, so the same operating temperature, the interception is larger, for more than 16mm lines, you can reduce a cross section, do not allow people to contact the place, you can reduce two cross sections.
4, waterproof, explosion-proof, corrosion resistance
Due to the use of seamless copper pipe as a sheath, so mineral insulated cable has waterproof, moisture, oil and some chemical substances damage performance, copper pipe has considerable mechanical strength, so it has better explosion-proof performance.
5, high working temperature
Since the melting point temperature of the insulating layer magnesium oxide crystal is much higher than the melting point temperature of copper, the maximum normal working temperature of the cable can reach 250 ° C, and it can continue to operate at 1083 ° C close to the melting point temperature of copper in the short term.
6, long service life
The inorganic materials used in mineral insulated cables can ensure that the cables have stability, long life and fire resistance, there is no insulation aging, and the service life can reach more than 3 times that of ordinary cables.
7. Small outside diameter
The diameter of mineral insulated cables is smaller than other cables with the same rated current.
8, high mechanical strength
Mineral insulated cables are robust and can withstand severe mechanical damage without compromising their electrical properties.
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.
10. Ground
For mineral-insulated cables, a separate ground lead is not required because the copper sheath used in this cable already acts as a ground lead and provides good low ground resistance. As far as grounding sheath loop (ESR) wiring is concerned, in MEN (multi-ground neutral) systems, the outer copper sheath can be used as a grounding and neutral conductor.
11, laying flexibility
Mineral insulated cables can be laid on the bridge with ordinary cables, and special brackets can also be used to lay out, which is more flexible than ordinary cable laying, but also saves the investment of cable bridge, and can reduce the overall cost of the project.
Application of mineral insulated cable
Mineral insulated cables are widely used in all walks of life, including high-rise buildings, petrochemical, airports, tunnels, ships, offshore oil platforms, aerospace, iron and steel metallurgy, shopping centers, parking lots and so on.
1. High-rise buildings
General lighting, emergency lighting, fire alarm, fire electrical lines, emergency elevator and lifting equipment lines, computer room control lines, trunk distribution system lines, dual power control lines
2. Oil platforms
General lighting, emergency lighting, potentially dangerous explosion area line
3. Parking Lot
General lighting, emergency lighting, fire alarm, smoke emission and ventilation lines
4. Airport terminal
General lighting, emergency lighting, fire monitoring system, fire alarm system
5. Nuclear Power Plant
General lighting, emergency lighting, computer room control line, large power line, high temperature environment power and control line, potentially dangerous explosion area line
6. Warships, ships
Power transmission lines, fire monitoring system, fire alarm system, smoke emission and ventilation lines, kitchen power lines, large power lines, dual power control lines, emergency lighting, emergency broadcast lines, computer room control lines
7. Chemical industry
General lighting, emergency lighting, potentially dangerous explosion lines and other places
8. Library, Museum, data processing center
Fire alarm control circuit, fire electrical circuit
9. Subway tunnels
General lighting, emergency lighting, fire monitoring systems, fire electrical wiring, smoke emission and ventilation wiring
10. Places of interest
General lighting, emergency lighting, fire alarm, fire electrical circuits
11. Iron and steel metallurgy
High temperature environment power and control lines, emergency power supply, large power lines, power supply lines that can not be cut off, power room transmission lines
12. Power Plant
Large power lines, general lighting, emergency lighting, fire alarm, fire electrical lines
13. Aerospace
General lighting, emergency lighting, computer room control line, large power line, high temperature environment power and control line, potentially dangerous explosion area line
14. Department stores
General lighting, emergency lighting, emergency broadcast, emergency elevator and lifting equipment lines
Mineral insulated cable adopts inorganic mineral insulating material as insulation, which is not affected by irradiation compared with conventional organic insulated cable (YJV, VV), the material will not age and deteriorate, and the insulation characteristics will not change; At the same time, the outer sheath of the cable is in the form of copper rolling, with excellent sealing, moisture resistance and corrosion resistance, and the service life of the cable can reach more than 70 years, which is definitely the best choice for a series of fields such as high-rise buildings.
Alice Wong
Alice
+86 18202169643