Disadvantages of BTTZ Mineral Insulated Cables
1. BTTZ mineral insulated cables have many joints and are susceptible to moisture, while BTLY mineral insulated cables can be manufactured without joints and still meet customer requirements.
2. The copper tube drawing process limits the continuous length of a single cable. Installation requires frequent joints, increasing material and labor costs and requiring special treatment of the electrical properties of the joints.
3. Cables over 35mm² are single-core cables, requiring multiple installation steps and compromising the electrical performance of each core. 2.4 The solid copper conductor, a core rod, is extremely rigid, limiting its maximum cross-section to 400mm². 2.5 The magnesium oxide powder used as the insulation layer can easily produce uneven thickness and can cause breakdown if the slightest process error occurs. The maximum rated voltage is 450/750V.
4. BTTZ cables use frequent joints, requiring special treatment to ensure they remain energized even after being exposed to water spray under flames. 5. Once exposed to fire, the copper outer casing of a BTTZ cable reaches a direct fire temperature of -950°C + 50°C (the plastic outer sheath burns instantly). The copper conductor core resistance increases with temperature rise, resulting in significant voltage drop losses in a fire. Furthermore, its structural characteristics preclude the use of aluminum conductors as cores.
6. The metal sheath is drawn in sections, with a maximum length of 60 meters per single cable. Magnesium oxide is environmentally polluting, expensive, and difficult to improve efficiency.
