Thread Content
This post was last edited by sdwfsgyykai on 2019-4-29 08:05. To ensure the surge protection performance of a Surge Protection Device (SPD), its connection conductors are very important. Connection conductors are divided into internal and external types. Today, Junhe Electronics will provide a detailed overview of the connection conductors in surge protectors as follows: 1. Internal connection conductors of surge protectors – The connection conductors inside a surge protector (SPD) should have a sufficient cross-sectional area, and their length should be as short as possible. The current density in the current-carrying conductor under impact current must not exceed the allowable value; otherwise, under high impact currents, the temperature rise of the conductor will be too high, potentially leading to its melting. The current technical standards for surge protectors do not specify requirements for the current density in the internal conductors. If the process of temperature rise in a conductor caused by an inductive current is approximated as an adiabatic process, that is, if all the energy generated by the inductive current is absorbed by the conductor, causing its temperature to increase by ΔT – given the allowable temperature rise ΔT for the conductor – then it is possible to calculate the allowable current density J for that conductor. According to professional calculations, the length of the connecting conductors in surge protectors should be kept as short as possible, in order to reduce the resistive and inductive voltage drops caused by the surge current along these conductors, as well as the electromagnetic forces acting on them. Generally, the resistive voltage drop across the connecting conductors in a surge protector is much smaller than the inductive voltage drop. Therefore, only the inductive component is usually considered. When calculating the limiting voltage of a surge protector, it is not permissible to simply add the inductive voltage drop of the conductor to the limiting voltage of the voltage-limiting component, as the phases of the two are different. In practical work, as a rough estimate that allows for some flexibility, the voltages can be simply added together to calculate the limiting voltage of the entire surge protector. II. External connection conductors of surge protectors The external connection conductors of surge protectors are mainly as follows: 1. The power supply connection wires should be multi-strand copper wires with a cross-sectional area of not less than 16 mm2, while the grounding wires should be multi-strand copper wires with a cross-sectional area of not less than 25 mm2. The connection wires should be as short, straight, and thick as possible, with a ground resistance of R≤4Ω. 2. A suitable fuse or circuit breaker should be connected in series at the front end of the modular surge protector. 3. The power supply must be disconnected during installation; operation while powered on is strictly prohibited, and the connection wires must meet the required standards. 4. After installation, insert the module in place and check whether it is working properly. 5. When the module fault indicator window turns red, the remote signal terminal outputs an alarm signal, indicating that the lightning protector has failed and should be replaced promptly. 6. Lightning arresters require no special maintenance; only regular checks are needed to ensure that their connections are secure and that the status indicators are functioning properly. In accordance with the requirements of the \"Technical Code for Lightning Protection of Electronic Information Systems in Buildings\" (GB50343-2012), the connection wires for surge protectors at various levels are as shown in the table below: http://www.junhedianzi.cn/uploads/ueditor/image/20190417/1555475054992422.jpg