Waterproof and dewetting solution for BTTZ cable installation
magnesium oxide crystalline powderBTTZ cableThe conductor and insulator in is a kind of high water absorption of raw materials, therefore, in the whole process of cable transportation and installation, once the outer sheath is slightly damaged, the magnesium oxide crystalline powder will return to moisture, thus causing the resistor to be greatly reduced. In addition, whenBTTZ cableIn the middle and terminal equipment interface made, will also make magnesium oxide crystalline powder moisture. For this situation, effective countermeasures should be taken on site. There are generally two conditions:
The wet end of the cable is dehumidified. At the end of the cable, generally speaking, the scope of moisture intrusion in the body is 300-400mm, but ifBTTZ cableThe end of the body is temporarily unsealed and exposed to the air for a long time, so moisture in the body can pass through about one meter. At this time, the damping end of the cable can be tilted upward and heated one meter from the end of the cable with a gasoline gush lamp for vehicles.BTTZ cableThe moisture in the magnesium oxide is slowly released from the inward type. In actual operation, the flame should be moved slowly to achieve symmetrical heating. Note that the ambient temperature of the control shaft sleeve is 200C to remove moisture. If the measured value of the grounding resistance after baking at one end is not large, then use the same method to bake again at the other end of the cable until the grounding resistance reaches the standard.
Find and repair the damage of the copper protective wire sleeve of the cable. When the copper sheath in the middle of the cable is broken at the construction site, the search and repair methods are as follows: first of all, if the grounding resistance on both sides of the cable does not rise or change little after the soft fire accident dehumidification, it can be judged as a common fault in the middle. The entire length of the cable can be baked with a gentle fire and searched with a high resistor digital multimeter. The actual way is to adjust the digital multimeter to the high resistor level, one end of the instrument panel is connected with the cable core, the other end is connected with the outer protective wire sleeve, and the gas furnace is used to bake along the bald head, and the change of the reading value of the meter needle is observed. If the reading value of the meter needle changes during cake baking parts, it is possible to identify common failure points here. After sawing, the cable is baked with a low fire, and the insulation layer value is checked after dewetting. Meet the standard, the resistance value meets the standard, and then connect the cable with the positive middle connector. When dehumidifying, pay attention to the change of heating temperature and friction resistance value. In addition, in the selection and applicationBTTZ cableIn the whole process, we should pay attention to some related problems:(1) First,BTTZ cableIt is used in key parts of multi-storey buildings, airports, ports, subway stations and other key housing buildings, such as fire safety monitoring centers, emergency lights, fire pumps, backup power supplies, smoke prevention and exhaust, etc. Sweett cooling fan. The route of electrical equipment such as the automatic fire alarm system is beneficial to reduce the project budget, reduce the construction period, and facilitate the construction and maintenance of the project. second,BTTZ cableThe terminal equipment is longer and more difficult to bend than ordinary cables. Therefore, when the power distribution cabinet is customized, sufficient indoor space for actual operation should be embedded. When laying cables, common tools should be used for cooling elbows to avoid damage to shaft sleeves. The terminal head and the middle connector shall be manufactured in strict accordance with the safety operation regulations, and the cleaning and cleaning on the spot in actual operation shall be maintained. The sealant, sealant and silicone rubber shall not be polluted by the residue environment, and the grounding resistance shall be guaranteed according to the standard regulations.