Light burned magnesium powder It is completely incombustible, and can operate continuously for a long time at 250 ℃. It can also maintain normal operation for 30 minutes at the limit state of 1000 ℃ without causing ignition source. Even in the case of flame barbecue, light burning of magnesium powder, as long as the flame temperature is lower than the melting point temperature of copper, the cable can continue to be used without replacement after the flame is eliminated. It will not produce toxic smoke and gas when it is roasted by flame.
2. Strong overload protection capability
When the line is overloaded, as long as the heating cannot reach the melting point temperature of copper, the cable will not be damaged. Even if the breakdown occurs instantaneously, the crystal at the breakdown will not form carbide. After the overload is eliminated, the performance of the cable will not change, and it can still continue to be used normally.
3. High operating temperature
Since the melting point temperature of the insulating layer crystal is far higher than that of copper, the maximum temperature of the cable for long-term normal operation can reach 250 ℃, and the cable can continue to operate normally in a short term at a melting point temperature close to 1083 ℃ of copper.
4. Good anti-corrosion and explosion-proof performance
As seamless copper pipe is used as sheath, light burned magnesium powder has the properties of waterproof, moisture, oil and some chemical substances. Copper pipe has considerable mechanical strength, so it has good explosion-proof performance.
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 3 times of that of ordinary cables.
6. Greater laying flexibility
Magnesia cable can be laid on the bridge with ordinary cable, and can also be laid on the open with special support, which is more flexible than ordinary cable laying, saves the investment in cable bridge, and reduces the overall cost of the project.
2、 Disadvantages of light burned magnesium powder
Everything has two sides, Light burned magnesium ball It is no exception. While it has many advantages, it also has some disadvantages, which should be paid attention to during selection and construction.
1. High investment cost
As the outer sheath of magnesium oxide cable is composed of seamless copper tube, the overall copper content is far more than that of ordinary cable, and the construction process of magnesium oxide cable requires higher equipment than that of ordinary cable, resulting in the price of magnesium oxide cable being about 30% higher than that of ordinary cable.
2. The joint is easily damped
The insulating layer is composed of minerals, which can easily react with the moisture in the air to generate conductive magnesium hydroxide. During the construction of cable head, when the cable end peels off the exposed conductor, the insulation resistance of the cable is generally above 10M Ω. However, if the cable head is not made within one hour, the insulation resistance can fall below 10M Ω, or even fall below 0.5M Ω. If the outer layer is not cut, and it is not found in time and sealed for moisture-proof treatment, the insulation value will quickly decline and gradually decline to 0, This will make the cable unusable.
3. Difficult construction
The hardness of light burned magnesia powder is higher than that of ordinary cables, and its weight is about twice that of ordinary cables. It is not easy to achieve a parallel and neat appearance when laying. Moreover, the line is long, there are many joints, and it is difficult to find fault points. Therefore, it is difficult to construct, and it is difficult to bend and form at the incoming and outgoing distribution boxes and in the bridge.
4. Large construction workload
Light burned magnesia powder is single core cable if the specification exceeds 35mm. For example, one 70mm cable only needs 3 × 70+2 × 35 Five conductors can be in the same outer sheath, while magnesium oxide must be spliced by three 70mm and one 35mm single core cables to reach the same specification. The delivery length of single core cable is short, for example, the delivery length of 240mm cable is 69m. If the laying distance is long, a large number of intermediate joints will be made, which will double the construction workload
