轻烧镁球的优缺点 Advantages and disadvantages of light burned magnesium balls

http://www.ykbhlm.com一、轻烧镁球的优点

1、完全防火

轻烧镁球自身完全不燃烧，250℃时可连续长时间运行，1000℃极限状态下也可以保持30分钟的正常运行，同时还不会引发火源。即使在有火焰烧烤的情况下，只要火焰温度低于铜的熔点温度，火焰消除后电缆无需更换仍可继续使用。在被火焰烧烤的情况下不会产生有毒的烟雾和气体。

2、过载保护能力强

线路过载时，只要发热达不到铜的熔点温度，电缆不会受损。即使瞬间击穿，击穿处氧化镁晶体也不会形成碳化物，过载消除后，电缆性能不会产生变化，仍可继续正常使用。

3、工作温度高

由于绝缘层氧化镁晶体的熔点温度远高于铜的熔点温度，因而电缆长期正常工作的最高温度可达250℃，短期内可在接近铜的熔点温度1083℃下继续正常运行。

4、防腐、防爆性能好

由于采用无缝铜管作护套，所以轻烧镁球具有防水、潮气、油和一些化学物质侵害的性能，铜管具有相当的机械强度故有较好的防爆性能。

5、使用寿命长

氧化镁电缆全部由无机材料构成，因而不存在绝缘老化，使用寿命可达到普通电缆的3倍以上。

6、敷设灵活性较大

氧化镁电缆可以与普通电缆敷设在桥架上，同时也可以采用专用支架明敷，比普通电缆敷设更具灵活性，也节省了电缆桥架的投入，可以降低工程整体造价。

二、轻烧镁球的缺点

事物都具有两面性，轻烧镁球也不例外，具有众多优点的同时，也存在着一些缺点，应该在选择和施工时加以注意。

1、投资成本高

由于氧化镁电缆外护套是由无缝铜管构成，整体含铜量远多于普通电缆，同时氧化镁电缆的施工工艺对设备要求高于普通电缆，造成氧化镁电缆价格与普通电缆相比高出30％左右。

2、接头处易受潮

绝缘层由矿物氧化镁组成，它极易与空气中的水分发生化学反应，而生成能导电的氢氧化镁。在电缆头施工中,电缆端头剥开裸露导体时，电缆的绝缘电阻一般在10MΩ以上，但如在1小时内未完成电缆头制作，绝缘电阻可下降到10MΩ以下，甚至会出现降到0.5MΩ以下的情况，如不注意划破外层，又未及时发现并作密封防潮处理，绝缘值会很快下降并会逐步下降到0，这样就会造成该电缆无法使用。

3、施工难度大

轻烧镁球硬度与一般电缆相比较高，重量约为一般电缆的2倍，敷设时不易达到平行整洁的观感效果，且线路长、接头多，查找故障点困难，因此施工难度较大，在进出配线箱处和桥架内弯曲成型困难。

4、施工工作量较大

轻烧镁球凡规格超过35mm的均为单芯电缆，如1根70mm的电缆，普通电缆只需3×70+2×35五根导体在同一外护套内即可，而氧化镁要达到同等规格须由3根70mm加1根35mm的单芯电缆拼合而成。单芯电缆的交货长度较短，例如240mm的电缆交货长度为69米，若敷设距离较长则会增加大量中间接头的制作，使得施工工作量成倍增加。

http://www.ykbhlm.com First, the advantages of lightly burned magnesium balls

1.Fully fireproof

The lightly burned magnesium ball itself does not burn at all, and can run continuously for a long time at 250 ° C. It can also maintain normal operation for 30 minutes under the limit of 1000 ° C, and it will not cause a fire source. Even in the case of flame grilling, as long as the flame temperature is lower than the melting point of copper, the cable can continue to be used without replacement after the flame is eliminated. Does not produce toxic fumes and gases when grilled by flames.

2.Strong overload protection capability

When the line is overloaded, the cable will not be damaged as long as the heat does not reach the melting point of copper. Even if the breakdown occurs instantaneously, the magnesium oxide crystals at the breakdown place will not form carbides. After the overload is eliminated, the cable performance will not change, and normal use can still be continued.

3.High working temperature

Because the melting temperature of the insulating magnesium oxide crystal is much higher than the melting temperature of copper, the long-term normal working temperature of the cable can reach 250 ℃, and it can continue to operate normally at a temperature close to the melting point of copper at 1083 ℃ in the short term.

4.Good anti-corrosion and explosion-proof performance

Because the seamless copper tube is used as the sheath, the light-burned magnesium ball has the performance of waterproof, moisture, oil and some chemical substances. The copper tube has considerable mechanical strength and therefore has better explosion-proof performance.

5.Long service life

All magnesium oxide cables are made of inorganic materials, so there is no insulation aging, and the service life can reach more than three times that of ordinary cables.

6. Large laying flexibility

Magnesium oxide cable can be laid on the bridge with ordinary cables, and at the same time, it can also be exposed with a special support, which is more flexible than ordinary cables, saves the investment of cable bridges, and can reduce the overall cost of the project.

Second, the disadvantages of lightly burned magnesium balls

Things are two-sided, and light-burned magnesium balls are no exception. At the same time, they have many advantages and also have some disadvantages, which should be paid attention to when selecting and constructing.

1.High investment cost

Because the outer sheath of the magnesium oxide cable is composed of seamless copper pipes, the overall copper content is much more than that of ordinary cables. At the same time, the construction process of magnesium oxide cables requires higher equipment than ordinary cables, resulting in the price of magnesium oxide cables compared to ordinary cables About 30% higher.

2, the joint is susceptible to moisture

The insulating layer is composed of mineral magnesium oxide, which easily reacts with moisture in the air to form conductive magnesium hydroxide. In the construction of cable heads, when the cable ends are stripped of bare conductors, the cable's insulation resistance is generally above 10MΩ, but if the cable head is not completed within 1 hour, the insulation resistance can drop below 10MΩ, or even drop to 0.5 In the case of below MΩ, if the outer layer is not noticed, and the seal and moistureproof treatment are not found in time, the insulation value will drop quickly and gradually decrease to 0, which will make the cable unusable.

3. Difficult construction

The light-burned magnesium ball has higher hardness compared to ordinary cables, and weighs about twice that of ordinary cables. It is difficult to achieve a parallel and neat look and feel when laying, and the lines are long and there are many joints. It is difficult to find fault points, so the construction is difficult. It is difficult to bend and mold at the entrance and exit of the distribution box and inside the bridge.

4. Large construction workload

Light-burned magnesium balls are all single-core cables with specifications exceeding 35mm. For example, a 70mm cable, ordinary cables need only 3 × 70 + 2 × 35 five conductors in the same outer sheath, and magnesium oxide must reach The same specifications must be composed of three 70mm and one 35mm single-core cables. The single-core cable has a short delivery length. For example, a 240mm cable has a delivery length of 69 meters. If the laying distance is long, a large number of intermediate joints will be produced, which will double the construction workload.