The light burned magnesia powder is completely unburned. It can run continuously for a long time at 250 ℃ and can keep normal operation for 30 minutes at 1000 ℃ limit state without 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 still be used without replacement after the flame is eliminated. In the case of being barbecued by fire, it will not produce toxic smoke and gas. Light burned magnesium powder
2. Strong overload protection capability
When the line is overloaded, the cable will not be damaged as long as the heating temperature does not reach the melting point of copper. Even if it breaks down instantaneously, the crystal at the point of breakdown will not form carbide. After the overload is eliminated, the performance of the cable will not change and it can still be used normally.
3. High working temperature
Because the melting point temperature of insulating layer crystal is much higher than that of copper, the cable can work normally for a long time up to 250 ℃, 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 tube is used as sheath, the light burned magnesium powder has the properties of waterproof, moisture, oil and some chemical substances. The copper tube has considerable mechanical strength, so it has good explosion-proof performance.
Light burned magnesium powder
5. Long service life
MgO cable is made of inorganic materials, so there is no insulation aging, and its service life can reach more than 3 times of ordinary cable.
6. Flexible laying
Magnesium oxide cable can be laid on the bridge with ordinary cable, and it can also be laid on the surface with special support, which is more flexible than ordinary cable laying, saves the investment of cable bridge, and reduces the overall cost of the project.
2、 Disadvantages of light burned magnesium powder
All things have two sides, and the light burning magnesium ball is no exception. It has many advantages, but also has some disadvantages, which should be paid attention to in the selection and construction.
1. High investment cost
Because the outer sheath of MgO cable is composed of seamless copper tube, the overall copper content is much higher than that of ordinary cable, and the construction technology of MgO cable requires more equipment than that of ordinary cable, resulting in the price of MgO cable being about 30% higher than that of ordinary cable.
2. Joints are susceptible to moisture
The insulating layer is composed of minerals, which can easily react with the moisture in the air to form conductive magnesium hydroxide. In the construction of cable head, When the exposed conductor is stripped off at the cable end, the insulation resistance of the cable is generally above 10m Ω. However, if the production of the cable end is not completed within 1 hour, the insulation resistance can drop below 10m Ω, or even below 0.5m Ω. If the outer layer is not scratched, and the sealing and moisture-proof treatment is not found in time, the insulation value will drop quickly and gradually to 0, which will cause serious damage The cable cannot be used.
3. The construction is difficult
The hardness of light burned magnesium powder is higher than that of ordinary cables, and its weight is about twice that of ordinary cables. It is not easy to achieve the appearance effect of parallel and clean when laying. Moreover, the line is long and there are many joints, so it is difficult to find the fault point. Therefore, the construction is difficult, and it is difficult to bend in and out of the distribution box and in the bridge.
4. The construction workload is large
All the light burned magnesium powder over 35mm are single core cables. For example, for a 70mm cable, the common cable only needs 3 × 70 + 2 × 35 conductors in the same outer sheath, while for magnesia to reach the same specification, it must be assembled by 3 70mm and 1 35mm single core cables. 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