| In view of the question that lightning surge creates damage easily to the sensitive electronic installation through power lines or signal lines in the low-voltage system.the installation of surge protection device should also be reasonable on the line to protect the electronic equipment,in addition to installing external lightning protection facilities effectively. According to regulation about the division of the lightning protection area, To determine the severity of lightning electromagnetic pulse,then to determine the design of SPD. The passage analyses the wave process using transmission line theory and energy coordination of multi-level surge protetion,proposes the method of analysing energy coordination of multi-level surge protetion with the transmission line theory.and proves its accuracy through the experiments.In order to study on the cooperation between levels of voltage-limiting low voltage SPD, a way to simulate the best coorperation between two-level SPD under the8/20us and the10/350μs impact current by using the electromagnetic transient p rogram (EMTP) simulation is presented. The MOV impulse equivalent circuit model is referenced by working group of IEEE. The simulation result is that the high-low coordination which under8/20μs impact current and the low-high coordination which under10/350μs impact current is the best way. Proposing a kind of reference for sensitive electronic equipment of lightning protection.According to the electrical property of RS-232data interface, the paper which combines theoretical analysis bring up a design of SPD structure for RS-232data.Used a large number of experiments, to make a detailed analysis for the selection of decoupling resistance, and prove that this SPD can effectively limits residual pressure value in the range of equipment tolerance in the transient current shock test. Meanwhile, the surge protector when it access systerm, has little influence to signal transmission that can ensure the normal operation of the systerm, when it accesses systemBased on the characteristics of transmission signaling of industrial control systems, for industrial sensor which output4～20mA DC signals, and combined with theoretical analysis, there came out a design project about the signaling SPD with filtering structure. Through a large number of experiments and the Cadence circuit simulation, it verified that the signal SPD had filter discrimination. And under the impulse tests of surge current, it can effectively limit the residual voltage within the tolerance which the device can take. The SPD can not only inhibit the lightning wave, but also filter out high frequency interference signal which came in the industrial control system, ensuring that the signal transmission system is stable. |
