3 Person Hot Tub 3 Person Hot Tub,portable outdoor hot tub,modern jacuzzi outdoor,spa in backyard,built in jacuzzi outdoor Guangzhou Aijingsi Sanitary Products Co.,Ltd , https://www.infinityedgehottub.com
**2-1 Wide Area Information System Electromagnetic Compatibility (EMC) Concept**
A wide-area information system (WAIS) refers to a network that spans large geographical areas and has direct electrical connections between its components. This type of system cannot achieve equipotential bonding, making it vulnerable to electromagnetic interference and potential safety issues. Security systems are considered part of the "wide area information system" due to their extensive reach and interconnected nature.
The external electromagnetic environment of a WAIS includes various factors such as atmospheric lightning, free-space electromagnetic waves, and underground potential differences. These elements can significantly impact the performance and reliability of weak systems, which are sensitive to electromagnetic disturbances.
Electromagnetic compatibility (EMC) for a wide-area information system is about ensuring that the system operates safely under the influence of these external electromagnetic conditions. It differs from traditional equipment-level EMC considerations, as it focuses on the overall system’s resilience rather than individual components. Some attempts have been made to apply PCB-level concepts to security systems, but this approach often leads to misunderstandings and ineffective designs.
The design of a secure security system involves multiple aspects of EMC, including anti-jamming, static protection, and both direct and induced lightning protection. The goal is to maintain system integrity and ensure safe operation in various environmental conditions.
However, many current practices, such as using "pole lightning rods" and "ground lightning protection devices," introduce artificial hazards. These issues arise from a lack of understanding of the earth's electromagnetic environment and the unique characteristics of wide-area systems. Addressing these problems requires a deeper focus on EMC design principles in security projects.
**2-2 The Basic Principle of Security System Safety Design: "Single Point Earthing"**
1. **Concept of "Single Point Earthing"**
Single point earthing means grounding the main system host at one point, while all remote devices remain insulated from the ground. This ensures that the system’s ground connection is centralized, minimizing the risk of ground loops and potential differences.
For example, in an optical cable transmission system, the front-end optical transmitter acts as the subsystem host and is grounded. Cameras connected via cables should be insulated from the ground to prevent unwanted current flow. This method avoids unnecessary electrical connections and enhances system stability.
2. **Implementation of "Single Point Earthing"**
In practice, the system host must be grounded at a single point, while all remote equipment remains isolated. This allows static charges to be safely discharged through the central grounding point, maintaining the system’s potential close to that of the earth.
Claims about "overvoltage" and "high potential" in lightning protection often stem from incorrect assumptions. Grounding at both ends of a cable does not eliminate potential differences, as the impedance and resistance of the grounding path play a critical role. Therefore, "single point earthing" is more effective in managing static charge rather than lightning-induced currents.
3. **Rationale Behind "Single Point Earthing"**
By eliminating ground loops, single point earthing effectively blocks the entry of lightning or grid-induced potentials into the system. This is a fundamental and practical approach to protecting against surges and interference.
Multi-point grounding introduces risks, such as ground potential rise and surge voltages, which can damage equipment. Real-world cases have shown that improper grounding leads to system failures and safety hazards.
4. **Benefits of "Single Point Earthing"**
Adhering to this principle helps avoid costly and complex grounding systems. It also serves as a critical test for identifying hidden design flaws in security systems. By focusing on a single, controlled ground point, the system becomes more reliable and easier to manage.
5. **Conclusion on "Single Point Earthing"**
This approach is essential for ensuring the safety and performance of security systems. It provides a clear framework for addressing electromagnetic compatibility and reducing the risk of damage from external influences.
**2-3 Questions About Lightning Protection of Buildings and Power Supply Systems in Security Engineering**
Security engineering companies often face questions about whether they should include building and power supply system lightning protection in their designs. However, the responsibility for such protections typically lies with the building owner or the designated lightning protection authority.
If a building and its power system have already passed safety inspections and maintenance checks, there is no need for the security system to handle additional lightning protection measures. The inclusion of such features in the security project may be redundant and could lead to unnecessary complexity and costs.
Many security projects mistakenly assume that lightning protection is solely the responsibility of the security team. However, proper lightning protection for buildings and power systems is a separate and specialized field. Most security engineering firms lack the necessary qualifications to handle such tasks effectively.
**2-4 Direct Lightning Protection Design for Security Systems**
1. All security equipment should operate within the protected area of existing building lightning rods and independent lightning protection systems. Transmission cables should be buried whenever possible to reduce exposure to direct lightning strikes.
2. Outdoor cameras mounted on poles require careful consideration. If a pole is exposed to high lightning risk, an independent lightning rod should be installed. The distance between the lightning rod and the camera pole should be greater than 4.5 meters to prevent counterattacks.
3. Installing a lightning rod on the camera pole is not recommended, as it increases the risk of lightning strike. Instead, use insulating materials like wood or concrete for the pole and plastic brackets for the camera mount.
4. Some suggest isolating the camera from the pole while using the pole as a lightning rod. However, this is not advisable, as conventional insulation cannot withstand the high voltage generated by lightning.
**2-5 About Lightning Sensing**
Lightning induction is often misunderstood. Terms like “lightning electromagnetic pulse,†“surge voltage,†and “lightning overcurrent†are frequently used but rarely explained clearly. These terms are often misapplied, leading to confusion and ineffective protection strategies.
False data, such as “leakage voltage†of tens of kilovolts, is often created by assuming multi-point grounding and introducing ground potential into the system. Such data is misleading and does not reflect the actual energy levels involved in lightning induction.
In reality, the energy from lightning radiation is minimal compared to the total energy of a lightning strike. Factors like frequency spectrum, antenna efficiency, directionality, and polarization greatly limit the amount of energy received by cables. As a result, the so-called “tens of kilovolts†and “thousands of amps†on cables are exaggerated and not scientifically accurate.
**2-6 Inductive Lightning Protection Design**
Inductive lightning protection focuses on limiting the voltage induced on cables rather than discharging the lightning current to the ground. A key component of this strategy is the installation of a voltage-limiting protection circuit at the input and output ports of the equipment.
This circuit ensures that the induced voltage remains below the maximum safe level for the system. It also prevents excessive voltage from reaching the load, protecting the equipment from damage.
For video transmission lines, the protection circuit should be designed based on the specific characteristics of the system, such as signal bandwidth and transmission method. Embedded protection circuits are highly effective and have been proven to significantly reduce the damage rate caused by lightning and ground loop interference.
**2-7 Room Lightning Protection**
The security room is usually located inside a building with an existing lightning protection system. The 220VAC power supply is generally considered safe, provided that it meets the basic design requirements for electrical isolation and grounding.
Lightning protection for the entire system is a comprehensive task. Focusing only on the room or using partial solutions like grounding surge protectors is insufficient. A complete and well-designed system, including single point grounding and line protection, is essential for long-term safety.
**2-8 Lightning Protection Concept in Security Engineering**
The ultimate goal of lightning protection in security systems is to ensure the safety and reliability of the equipment and operations. This requires a clear understanding of both lightning protection principles and the technical characteristics of weak current systems.
Direct lightning protection should be handled by independent lightning rods, while induced lightning protection relies on effective line protection. Using grounding surge protectors or improperly installed lightning rods can create serious safety risks.
Establishing the concept of "wide area information system EMC design" is crucial. "Single point earthing" is the foundation of lightning protection, anti-interference, and system safety in security systems. Understanding lightning probabilities and avoiding blind investments in protection measures are also important steps in designing a truly effective and safe system.
**Conclusion**
Currently, the security and lightning protection industry faces challenges due to a lack of understanding of both weak current technology and lightning protection principles. Many projects are designed without proper knowledge, leading to safety hazards and inefficiencies.
Standards and guidelines should be developed with input from experts who understand both fields. Otherwise, poorly designed systems can create more harm than benefit. Ultimately, lightning protection is a practical science, and real-world testing is the best way to evaluate its effectiveness.
As professionals, we must prioritize scientific development and ensure that our systems are safe, reliable, and built with sound engineering principles.