Light burnt magnesia powder



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Advantages and Disadvantages of Light Burned Magnesium Powder

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Advantages and Disadvantages of Light Burned Magnesium Powder

Date:2017-03-11 author:Hongkai Fire Resistance click:

Light-burned magnesia powder does not burn at all. It can run continuously for a long time at 250 C. It can also maintain normal operation for 30 minutes at 1000 C limit state without initiating fire source. Even in the case of flame barbecue, as long as the flame temperature is lower than the melting point temperature of copper, the cable can continue to use without replacing after the flame is eliminated. Toxic smoke and gases are not produced when roasted by flame.

2. Strong overload protection capability

When the line is overloaded, the cable will not be damaged as long as the heating does not reach the melting point temperature of copper. Even if the breakdown occurs instantaneously, the crystals at the breakdown will not form carbides. After the overload is eliminated, the performance of the cable will not change and it can continue to work normally.

3. High working temperature

Because the melting point temperature of insulating layer crystal is much higher than that of copper, the maximum temperature of cable working normally for a long time can reach 250 C, and can continue to operate normally near the melting point temperature of copper 1083 in a short time.

4. Good anti-corrosion and explosion-proof performance

Because seamless copper pipe is used as sheath, lightly burned magnesia powder has the properties of waterproof, moisture, oil and some chemical substances, and copper pipe has good explosion-proof performance because of its considerable mechanical strength.

5. Long service life

Magnesium oxide cables are all made of inorganic materials, so there is no insulation aging, and their service life can be more than three times that of ordinary cables.

6. Flexibility of laying

Magnesium oxide cable can be laid on bridge frame with ordinary cable, and special bracket can also be used for open laying. It is more flexible than ordinary cable laying. It also saves the investment of cable bridge frame and reduces the overall cost of the project.

2. Defects of Light-burned Magnesium Powder

Everything has two sides. Light burnt magnesia ball is no exception. It has many advantages, but it also has some shortcomings. It should be paid attention to in the selection and construction.

1. High investment cost

Because the outer sheath of magnesium oxide cable is composed of seamless copper tube, the overall copper content is much more than that of ordinary cable, and the construction technology of magnesium oxide cable requires higher equipment than that of ordinary cable, resulting in the price of magnesium oxide cable is about 30% higher than that of ordinary cable.

2. Moisture susceptibility at joints

The insulating layer is composed of minerals, which can easily distribute biochemical reactions with water in the air and produce conductive magnesium hydroxide. In the construction of cable head, when the bare conductor is peeled off at the end of the cable, the insulation resistance of the cable is generally over 10M_, but if the cable head is not made in an hour, the insulation resistance can be reduced to below 10M, or even to below 0.5M. If the outer layer is not cut carefully, and the sealing and moisture-proof treatment is not found in time, the insulation value will decrease quickly and gradually to 0.5M. This will make the cable unusable.

3. Difficulty in construction

Compared with ordinary cables, the hardness of lightly burned magnesia powder is higher and its weight is about twice that of ordinary cables. It is not easy to achieve the effect of parallel neatness when laying, and the line is long and there are many joints. It is difficult to find fault points. Therefore, it is difficult to construct lightly burned magnesia powder, and it is difficult to bend in and out of wiring box and bridge frame.

4. Construction workload is large

All lightly fired magnesia powders with specifications exceeding 35mm are single-core cables. For example, a 70mm cable, ordinary cables only need 3*70+2*355 conductors in the same outer sheath, while for magnesium oxide to reach the same specifications, three single-core cables with 70mm and one 35mm must be assembled. The delivery length of single-core cable is shorter, for example, the delivery length of 240mm cable is 69 meters. If the laying distance is longer, a large number of intermediate joints will be made, which will double the construction workload.

Light burnt magnesia powder