I. Introduction The program-controlled exchange system is an indispensable and important component of modern communication networks, serving as one of their pillars. The ZXJ10 program-controlled exchange is a crucial part of the Ganzhou, Jiangxi communication network. A failure in this system would not only result in economic losses but, more seriously, directly impact the region's economic and municipal development. Therefore, strengthening the security protection of the ZXJ10 program-controlled exchange is of paramount importance. The most critical component of the ZXJ10 program-controlled exchange is the integrated circuit (IC). ICs have relatively low interference immunity; even lightning electromagnetic pulses (LEMPs) induced from cables can damage IC components. Therefore, program-controlled exchanges are highly susceptible to lightning strikes. Currently, the ZXJ10 exchange has weak lightning protection performance, posing significant risks, and its circuit boards are easily damaged by lightning strikes. To fundamentally and comprehensively solve the lightning protection problem of the ZXJ10 equipment, improve its lightning resistance, and reduce the damage rate of circuit boards, we have implemented a separate lightning protection design. This design improvement has been piloted in multiple systems with good results. To better promote and implement the lightning protection improvement project... Below, I will analyze and discuss comprehensive lightning protection issues in conjunction with the ongoing ZXJ10 program-controlled exchange lightning protection project in Ganzhou, Jiangxi Province. II. Classification and Prevention Principles of Lightning Disasters Lightning strikes can produce the following different forms of damage: 1. Direct Lightning Strike: When lightning current directly enters metal pipes or wires during a lightning strike, it can travel a long distance along these pipes or wires. When the lightning current travels from the wire to electrical equipment, such as electrical or electronic equipment, a powerful lightning shock wave and its reflected component will appear. Although the amplitude of the reflected component is not as large as the shock wave, its destructive force far exceeds the load capacity of microelectronic devices such as semiconductors or integrated circuits, especially when it is superimposed on the shock wave to form a standing wave, becoming a powerful destructive force. 2. Lightning Induction: The damage caused by induced lightning is also called secondary damage. The lightning current has a large gradient, generating a strong alternating magnetic field, causing induced currents in surrounding metal components. This current may discharge to surrounding objects; if there are flammable materials nearby, it can cause fires and explosions. When induced onto connected wires, it can cause severe damage to the equipment. 3. Lightning surge intrusion: Due to the effect of lightning on overhead lines or metal pipes, lightning surges may intrude into buildings along these lines, endangering personal safety or damaging equipment. 4. Lightning electromagnetic pulse: Effects caused by direct lightning strikes and nearby lightning strikes as interference sources. The vast majority of these interferences occur through conductors, such as lightning current or partial lightning current, potential rise in devices struck by lightning, and magnetic radiation interference. Lightning disasters are known as "a major public hazard of the electronic age," with instantaneous overvoltages such as lightning strikes, induced lightning strikes, and power supply spikes becoming the main culprits for damaging electronic equipment. Analysis of numerous cases of lightning strikes on communication equipment has led experts to conclude that lightning electromagnetic pulses (LEMPs) caused by lightning induction and lightning surge intrusion are the primary cause of damage to communication equipment. Therefore, our prevention principle is "overall defense, comprehensive management, and multiple protections," striving to minimize the damage caused. III. Main lightning protection measures 3.1 A sound grounding system Grounding is the most basic and effective measure in a lightning protection system. 3.1.1 According to the different functions of "grounding," grounding can be divided into "working ground," "protective ground," and "lightning protection ground," etc. For important communication equipment systems, a "working ground" is essential, providing a standard reference potential for the entire system. With this reference potential, the system can function normally. If the system is also powered by a high-voltage power supply, the equipment casing must be connected to a "protective ground." If the system has outdoor overhead metal equipment or cables connected to it, a "lightning protection ground" must be connected in a suitable location to prevent high voltage from lightning strikes from entering the system. 3.1.2 If the "working ground," "protective ground," and "lightning protection ground" of a communication system are installed separately and not connected to each other, forming an independent system, we call it a "separate grounding system." If the three are combined into a unified grounding system, we call it a "combined grounding system." Currently, most communication buildings in Ganzhou, Jiangxi Province, use a combined grounding system. A combined grounding system eliminates potential differences that may exist between different grounding points, and can better suppress discharge phenomena between different grounding points during a lightning strike. 3.1.3 The grounding of the PBX and the grounding of the entire building it is located in are very important. According to the standards of the Ministry of Information Industry, the impulse grounding resistance of lightning protection grounding in telecommunications buildings should not exceed 10 ohms (YD5003-94 "Design Code for Telecommunications Dedicated Buildings"), and the grounding resistance of important telecommunications buildings should be below 1 ohm (YDJ20-88 "Provisional Technical Regulations for Installation Design of PBX Equipment"). If the grounding does not meet the requirements, serious damage may occur when the PBX is struck by lightning. 3.1.4 In the actual wiring process, a wiring method similar to "distributed grounding" is adopted, that is, both the working ground wire and the protective ground wire are led out from the grounding busbar, and the two types of ground wires are not directly connected nearby, as shown in Figure 1. Its advantage is that when lightning current flows through the grounding grid, the lightning current only flows longitudinally, and even if there are poor contact points, it will not cause lateral interference. 3.1.5 Grounding treatment of the PBX: Use a 135mm² multi-strand copper core wire to connect it separately to the grounding busbar. Unlike the system, (1) it is not directly connected to the positive terminal of the switch, nor is the cabinet randomly connected to cables or wires with positive terminals. (2) The contact parts between the cabinet and the raised floor and base are insulated, which is equivalent to adopting the "floating grounding" method to prevent static electricity and stray currents from the adjacent surface layer from entering the cabinet and interfering with communication. 3.1.6 Grounding of the main distribution frame: Two 50mm2 multi-strand copper core wires are introduced separately from the busbar, one of which is connected to the base of the distribution frame, and the other is connected to the grounding copper busbar at the top of the distribution frame. The advantages of dual-wire grounding are: on the one hand, it can improve the reliability of security equipment and alarm signal circuits; on the other hand, when the communication line is struck by lightning and high voltage current enters the ground through the protector, the potential on the distribution frame can be quickly reduced. After adopting the combined grounding method, the grounding of the equipment and the floor is more reliable, effectively ensuring the safety of equipment and personnel. 3.2 Reasonable Integrated Cabling The cabling of the ZXJ10 PBX is a highly specialized task, and its cabling scheme takes lightning safety into account during the design phase. Cabling work includes the PBX's trunk lines, internal lines (user cables, etc.), power lines, and indoor grounding wires. 3.2.1 The PBX's transmission network outdoors uses both overhead and buried methods. For overhead cables, telephone lines or cables should be buried before entering the building, with a burial length >2ρ (ρ is the resistivity of the grounding resistance, in Ω*m), and an actual length >50m. Buried cables are generally directly buried using metal armored cables or non-metallic shielded cables directly buried in metal conduits. From a lightning protection perspective, buried cables should be chosen for indoor entry when conditions permit. 3.2.2 The PBX's transmission network indoors should be laid along dedicated signal cable trays, avoiding laying along building structural columns or close to exterior walls; strong and weak current cables should not be laid in the same tray to reduce interference. For example, in a dispatch center building in Shaanxi Province, there was no dedicated signal cable tray; the signal lines and power lines were laid in the same tray. When the power line was struck by lightning or induced by a lightning pulse, an electromagnetic pulse was also induced on the signal line, which was then transmitted along the signal line to the switch, causing damage to the switch. 3.3 Determining Current Diversion and Voltage Limiting Measures 3.3.1 Program-controlled telephone lines and dedicated data lines entering the building should be equipped with surge protectors. When selecting surge protectors, the starting voltage should be 1.5 times the peak value of the protected line signal voltage, the lightning current flux should be greater than or equal to 0.2kA, the characteristic impedance should be 600 ohms, and the operating frequency should be 0-5MHz. 3.3.2 For outdoor receiving devices with signal lines connected to indoor equipment, a surge protector of the appropriate type should be connected in series between the antenna receiving device's lead-in line and the equipment. 3.3.3 The signal surge protectors installed on the above lines and equipment should be grounded nearby, with a grounding resistance of less than 4 ohms (for some special grounding requirements, less than 1 ohm). Furthermore, its grounding wire should not be connected to the lightning rod or lightning protection strip; it should be connected to the grounding wire of a dedicated surge arrester and directly connected to the grounding grid. Installing surge protectors (commonly known as lightning arresters) on power lines and signal lines will promptly divert the lightning current to the ground during lightning electromagnetic pulse attacks, thus providing protection. When selecting surge protection devices, pay attention to their response time. Some surge protectors remain intact even when the protected device is damaged during lightning current intrusion because their response time is too slow. Currently, line surge arresters using zinc oxide resistors (also known as varistors) as their core components are more popular in the market, offering faster response times and better performance. 3.4 Adding Lightning Protection Equipment 3.4.1 Installing Power Supply Surge Protection Boxes; (Diagram of power supply surge protection box installation in the equipment room) 3.4.2 Installing HW Cable Adapter Cards HW surge protection adapter cards are used to add Schottky diode protection to the LVDS signals of some older versions of the ZXJ10 V10.0 switch boards. Depending on the different HW cable interfaces and backplanes of each board, different adapter cards are designed, including PBCTN, PBROM, PCOMA, PCOMM, PDSN, PDSNI, PDTI, PODT, PREPD, and PSP. Adding this adapter card enhances the switch's anti-static and lightning protection capabilities. 3.5 Other Effective Measures 3.5.1 Determining Equipotential Bonding in the Communication Equipment Room: All metal devices, external conductive objects, power lines, communication lines, and other cables entering and exiting the equipment room should be properly equipotentially bonded to the main busbar. An equipotential bonding network should be installed in the equipment room and connected to the building's grounding system. The equipotential bonding network should preferably adopt an M-shaped network, with the DC ground of each device connected to the equipotential bonding network along the shortest possible distance. 3.5.2 Shielding Principles for Switches: In addition to signal and power lines, the switch room itself should also be shielded (including spatial and line shielding). Specifically, metal doors, windows, ceiling joists, and anti-static flooring should be grounded. Uniform potential distribution at all points ensures good shielding protection for personnel and equipment inside. IV. Conclusion In modern communication systems, a well-designed lightning protection system is crucial for the safe operation of equipment, not just for the ZXJ10 program-controlled switch. Only by strictly adhering to the principles of comprehensive lightning protection and planning protection from all possible lightning strike paths can the safe operation of the entire communication network be guaranteed.