Low Smoke PVC Cable

When the resistance of the cable conductor does not meet the requirements, it will cause the cable to overheat during operation. When the voltage source is connected to the external load, it is considered that the internal resistance is in series with the external load. When using it, it is required that the internal resistance of the voltage source be as small as possible. When the voltage and material are the same, the better the material of the conductor, the lower the resistance. Power lines are generally made of copper coated aluminum or oxygen free copper. According to the resistivity of copper and aluminum wires: 1.At the same temperature, the resistivity of copper wire is 0.0175 Ω, while the resistivity of aluminum wire is 0.0294 Ω. The shorter the length of the power cord, the lower the resistance, and the larger the cross-sectional area, the lower the resistance. For most conductors, there is also a certain relationship with temperature. The higher the temperature, the greater the resistance, but for a few conductors, the resistance decreases with increasing temperature. 2. Local damage to the cable sheath can cause slow damage to the insulation performance after water ingress, resulting in a gradual decrease in insulation resistance and overheating during cable operation. During installation, the cables are arranged too densely, resulting in poor ventilation and heat dissipation. 4. The cable is too close to other heat sources, resulting in abnormal heat dissipation. 5. Poor joint manufacturing technology and loose crimping result in excessive contact resistance at the joint, leading to cable overheating. 6. Poor insulation performance between cables leads to low insulation resistance and overheating during operation.

Fire-resistant cables are mainly used in power supply circuits from emergency power supplies to user fire protection equipment, fire alarm equipment, ventilation and smoke exhaust equipment, navigation lights, emergency power sockets, emergency elevators, etc.   Workers need to pay attention to the following issues when installing fire-resistant cables When fire-resistant cables are used in cable fermentation tunnels, cable interlayers with dense cables, or in flammable places such as near oil depots, Class A fire-resistant cables should be selected first. Except for these situations and when the number of cable configurations is small, Class B fire-resistant cables should be selected.   Fire-resistant cables are mostly used as power supply circuits for emergency power supplies and are required to function normally in case of fire. Since the ambient temperature rises sharply during a fire, in order to ensure the transmission capacity of the line and reduce the voltage drop, for circuits with long power supply lines that strictly limit the allowable voltage drop, the cross-section of the fire-resistant cable should be enlarged by at least one level.   Fire-resistant cables cannot be used as high-temperature resistant cables.   In order to reduce the probability of cable joint failure in a fire accident, the number of joints should be minimized during installation to ensure that the line can work normally in a fire. If branch wiring is required, the joints should be fireproofed.