How much do you know about mineral cables?

Mineral cables generally refer to mineral insulated cables, which can be divided into mineral fire-resistant cables in the mineral insulated cable industry. It is a cable made of inorganic materials. The outer layer of the cable is a seamless copper sheath, and there is a tightly compacted magnesium oxide insulation layer between the sheath and the metal core. Divided by different purposes: power distribution, heat tracing cables and heating elements, thermocouples and compensation, special, etc.

Characteristics of Mineral Cable Use

1. Safety

Made of copper and magnesium oxide. The melting point of copper is 1083 ℃, and the melting point of magnesium oxide is 2800 ℃. Therefore, when the temperature does not exceed 1000 ℃, the structure will not have any problems. Therefore, in most places, it will not disintegrate due to melting or burning, let alone spread. The insulation layer is made of inorganic materials and does not emit any smoke or harmful gases. In contrast, traditional methods (including flame retardant, low smoke and low halogen, low smoke and cable) can produce smoke and harmful gases when ignited, burned or subjected to long-term overload insulation damage.

2. Fire resistance performance

The currently commonly used PVC cables (ordinary, flame-retardant, fire-resistant, etc.) have a maximum working temperature of 70 ℃. Exceeding this temperature accelerates the aging of the insulation layer, shortens its lifespan, and causes a fire. According to the British BS6387 cable fire resistance testing standard, only mineral cables can meet the following three tests: A: 950 ℃ open flame combustion for 3 hours, B: 650 ℃ open flame combustion with water spray for 15 minutes, C: open flame combustion at 950 ℃, with a heavy object impact every 30 seconds. Domestic fire-resistant cables (NH-VV) can only meet the Class A test in GB12666.6-90 fire resistance: open flame combustion at 950 ℃ for 90 minutes. But most manufacturers’ fire-resistant cables can only meet Class B testing requirements; An open flame burns at 750 ° C for 90 minutes.
3. High load-bearing capacity
Due to its normal operating temperature of up to 250 ℃. IEC60702 specifies a continuous operating temperature of 105 ℃. This is due to the consideration of terminal sealing materials and safety requirements. However, its current blocking ability far exceeds other cables because magnesium oxide powder has better conductivity than plastic. Therefore, at the same working temperature, a larger current blocking ability can be reduced by one section for lines over 16mm and two sections for areas that cannot come into contact with people.

4. Waterproof, explosion-proof, and corrosion-resistant

Due to the use of low smoke, halogen-free, and highly flame-retardant materials for the sheath, it has high corrosion resistance (plastic outer sheath is only required in certain chemical corrosion scenarios), and the conductor, insulation, and sheath are dense Therefore, it not only prevents damage from water, moisture, oil, and some chemicals, but is also suitable for connecting various explosion-proof equipment and equipment in explosive hazardous areas.
Characteristics and Applications of Mineral Cables
Compared with organic materials, it has high temperature resistance, fire resistance, explosion resistance, and non flammability (can operate continuously for a long time at 250 ℃, and can also operate for 30 minutes at 1000 ℃). High load-bearing capacity, small outer diameter, and strong mechanical strength. High, long service life, generally without the advantage of a separate grounding wire. Mineral cables are widely used in passenger flow concentration areas such as nuclear power plants, metallurgy, chemical industry, mining, aerospace, high-rise buildings, airports, docks, underground railways, etc., to protect the power supply of fire pumps, fire elevators, important loads, emergency evacuation instructions, as well as important fire equipment such as fire prevention and smoke exhaust systems.