BTTZ mineral cables are high fire resistance cables with copper core, copper plating and magnesium oxide insulation. This type of cable is new generation and is made up of solid copper rod conductor, an outer coating of seamless copper tube and an intermediate filling of magnesium oxide crystalline powder as an insulating material. It has characteristics such as resistance to high temperatures, fire and explosion proof. It can operate long-term continuously at a temperature of 250°C and maintain short-term operation of 30 minutes in extreme conditions of 1000°C. BTTZ mineral cables have a high current capacity, a small outside diameter, high mechanical resistance and long service life, generally without the need for a separate grounding conductor.
Table of Contents
- BTTZ Series Mineral Cable Specifications
- Advantages of the BTTZ Cable
- Disadvantages of the BTTZ Cable
- Manufacturing of BTTZ Mineral Insulated Cable
- Installation Method of the BTTZ Mineral Cable
- Resume
According to the regulations, in fire protection design of construction projects, fire systems must use mineral insulated cables. The BTTZ is a model of MICC cable mineral, and other models include YTTW, BTLY, BBTRZ, among others.
The BTTZ cable is of high quality, with a high rigidity solid conductor. Its installation is complex due to the number of connectors required and the rigorous specifications of the installation process, which also raises its price. The mineral insulated cables commonly used on the market have been improved based on the standard fire performance of the BTTZ mineral insulated cable..
BTTZ Series Mineral Cable Specifications
| Level | Nominal voltage | Type | Name | Number of cores | Section mm² |
|---|---|---|---|---|---|
| Light load | 500V (450/750V) | BTTQ | Copper mineral insulation cable with lightweight copper core shield | 1, 2, 3, 4, 7 | 1.0-4.0 |
| BTTVQ | Copper mineral insulation cable with lightweight copper core shield and polychloroethylene jacket | 1, 2, 3, 4, 7 | 1.0-4.0 | ||
| Heavy load | 750V 600/1000V | BTTTZ | Copper mineral insulation cable with heavy copper core shield | 1, 2, 3, 4, 7, 12, 19 | 1.5-400 |
| BTTVZ | Copper mineral insulated cable with heavy copper core shield and polychloroethylene and ethylene ether jacket | 1, 2, 3, 4, 7, 12, 19 | 1.5-400 |
Use: The section of 25mm² or more of multi-chamber cables is composed of single core cables.
Advantages of the BTTZ Cable
- Completely fireproof: The BTTZ cable is completely non-combustible and does not cause fires. It can continue operating after extinguishing the flames if they do not exceed the melting point of copper. They have a fire resistance higher than that of normal fire resistant cables.
- High overload protection capacity: If the line is overloaded, as long as the heat generated does not reach the melting point of copper, the cable will not be damaged.
- High working temperature: The magnesium oxide glass insulating layer of BTTZ cable has a much higher melting point than copper, allowing a normal working temperature of up to 250°C.
- Excellent corrosion and explosion resistance: Seamless copper tube coating is waterproof, moisture and chemical corrosion, and also provides explosion-proof features.
- Long useful life: BTTZ cable is composed entirely of inorganic materials, which prevents insulation aging and prolongs its useful life up to more than three times that of common cables.
Disadvantages of the BTTZ Cable
- Expensive: It is cable is made of special materials and contains more copper than common cables, so its price is approximately 30% higher.
- High installation difficulty: The BTTZ is a rigid cable with mineral insulation, with greater hardness than common cables and approximately twice the weight, which complicates its installation.
- High volume of work: BTTZ cables of more than 35 mm are single core, which significantly increases the number of intermediate connections required and, but still, installation workload.
Manufacturing of BTTZ Mineral Insulated Cable
The manufacturing of mineral insulated cables mainly uses two raw materials: copper and magnesium oxide, who become the driver, the insulating layer of magnesium oxide and copper coating. The oxygen-free copper bar used in these cables has a purity of 99.99%, is subjected to tank annealing and has an elongation of at least 35%.
BTTZ cable production process
- Raw materials acquisition: Purchase of copper bars and copper tubes (from 13 a 15 metros).
- Cleaning and preparation: Cleaning copper bars and tubes.
- Mounting: Installing the components (copper tube, copper bar and calcined magnesium oxide prefabricated components).
- Stretched and annealed: Stretching and annealing of the whole.
- Production of the final cable: Additional stretching until the final product is obtained.
after production, earth resistance tests and voltage tests are carried out.
Installation Method of the BTTZ Mineral Cable
- Cable cutting: Cut the wire to the required length using a pipe cutter to make a cutting line on the surface.
- Removal of the coating: Use diagonal pliers to hold the copper plating in the middle of the shaft and turn clockwise. Continue turning until you reach the edge of the inner layer of the liner, making small rotations to the cutting line.
- Insulator cleaning: With a clean, dry cloth, completely expose the magnesium oxide insulating layer of the conductor. Place the ferrule on the cable and screw the copper sealing cup into the inner layer of the cable jacket. Initially, Screw by hand and slide clamping head over cup to check verticality. Once verticality is assured, use pipe pliers to hold the base of the compression tap and continue installation.
- Cable heating: Heat the wire with a blowtorch lamp from approx. 600 mm from the open end of the cable and direct the flame towards the open end of the cable to remove moisture. Remember to move the flame only toward the open end of the cable to prevent moisture from moving into the cable..
- Resistance measurement: Use a voltmeter to measure the resistance to ground between the core and the core, and between the core and the cladding. If the results meet the requirements, you can fill the sealing cup with sealing compound.
- Application of sealing compound: Add sealing compound slowly from one side to allow air to escape. Once the sealing compound is filled, put the cup lid on and then cover the conductors with heat shrink tubing.
Resume
In summary, BTTZ mineral cables stand out for their high fire resistance, high overload protection capacity, resistance to extreme temperatures, corrosion and explosion resistance, and long life. These cables are made up of a solid copper conductor, a seamless copper coating and magnesium oxide insulation, what gives them their exceptional properties. Nevertheless, They have disadvantages such as high cost and complex installation due to their rigidity and weight.. Despite these challenges, BTTZ cables are a safe and durable option for critical fire protection applications and in demanding industrial environments.