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A brief discussion on the classifications of mineral-insulated fire-resistant cables

Release date:

2023-01-16 10:25

Source:

　　So far, Mineral-insulated fire-resistant cable It is one of the more popular product categories in the cable industry. Fire-resistant cables are classified differently depending on their structural variations. But before we discuss how fire-resistant cables are categorized, let’s first take a look at what exactly makes up the structure of a cable.

　　Mineral-insulated fire-resistant cables are all composed of three key components: conductors, an insulation layer, and a metallic shield with a protective covering.

　　Conductor: A conductor is used to transmit electricity. The core material of conductors typically consists of copper or aluminum. Conductors can come in various configurations, including single-core, dual-core, three-core, four-core, and five-core designs. As such, the conductor is a crucial component of any cable or wire assembly.

　　The mineral-insulated fire-resistant cable's insulation layer is designed to maintain electrical insulation between the power conductor, copper core cable, and the external environment—where the copper core cable serves as the pathway for current flow. The insulation layer consists of primary insulation and overall wrapping insulation, with the wrapping insulation applied over and separate from the phase-specific insulation layers. The materials used for the insulation layer include mineral oil, plastics, polyethylene, high-voltage polyethylene, and high-density polyethylene.

　　Metal shielding: Cables rated 15kV and above typically feature both a conductor metal shield and an insulation shielding layer.

　　Mineral-insulated fire-resistant cable protective layer: The protective layer is divided into two parts—inner and outer sheaths—as well as an additional outer jacket. Its primary function is to safeguard the cable from external debris and moisture, effectively preventing damage caused by external forces that could compromise the cable's integrity.

　　What are the different types of mineral-insulated fire-resistant cables? Common ones include BBTRZ, BTTRZ, BTTVZ, NG-A, YTTW, and BTTZ cables.

　　BBTRZ: is a next-generation flexible fire-resistant cable—a type of mineral-insulated, fireproof cable that doesn’t feature a metal sheath. It not only inherits the various characteristics of traditional fire-resistant cables but also boasts flexibility, making its installation requirements as straightforward as those for standard cables.

　　BTTRZ: Belonging to the category of mineral-insulated power cables, it is a flexible, fire-safe electrical cable. The manufacturing process of BTTRZ cables is similar to that of BTTZ cables—both rely on robust mineral insulation—but BTTRZ cables incorporate enhanced flexibility and flame-retardant properties, making them easier to transport, highly bendable, and significantly safer to use.

　　BTTVZ: Mineral-insulated electrical cables, also known as fire-resistant cables, feature an additional outer sheath built upon the foundation of BTTZ mineral-insulated electrical cables.

　　NG-A: The outer sheath is entirely made of aluminum—specifically, it’s constructed by wrapping copper foil around a core, followed by electric welding and embossing into an aluminum-coil structure. Inside, the cable cores may be wrapped multiple times with layers of fire-resistant insulation tape.

　　YTTW: The cable, representing flexible fire-resistant cables/flexible mineral-insulated fire-resistant cables, is made by twisting multiple copper cores together and features excellent bendability.

　　BTTZ: is a type of cable featuring a seamless, spliced air-conditioning copper tube sheath on the surface, with lightweight magnesium oxide crystalline powder filling the center as an insulating material. The conductor consists of a single aluminum rod.


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