(1) Radiated electromagnetic fields (EMI) are generated from the interference space of various sources, including power networks, transient electrical equipment, lightning, radio, TV, radar, and high-frequency heating devices. This type of interference is commonly referred to as radiation, and its distribution is quite complex. When a PLC system is placed in an RF field, it can experience radiated interference that affects the system through two main paths: first, by directly inducing signals within the PLC circuit; second, by introducing interference through the communication lines connected to the PLC network. The level of this interference depends on the size and frequency of the electromagnetic field produced by nearby equipment. To reduce these effects, shielded cables, partial shielding of the PLC, and high-voltage bleeder components are typically used. (2) Interference introduced via external leads, such as power and signal lines, is known as conducted interference. In industrial environments, especially in China, this form of interference tends to be more severe due to the presence of multiple electrical devices and unstable power conditions. (3) Power supply-related interference is a common cause of PLC system failures. For instance, during the debugging of a specific project, the author observed that replacing the PLC power supply with one that had better isolation performance resolved the issue. Normally, PLC systems are powered by the grid, which covers a wide area and is susceptible to various forms of electromagnetic interference. Voltage fluctuations, surges from switching operations, and harmonics caused by rotating machinery can all affect the power supply. Although isolated power supplies are often used, they may not provide perfect isolation due to factors like distributed capacitance and manufacturing limitations. (4) Signal lines also introduce interference into the PLC control system. These lines carry both useful signals and unwanted external noise. One common source is interference from the power grid affecting the transmitter or shared signal meter, which is often overlooked. Another is electromagnetic radiation from the surrounding environment, which induces interference in the signal lines. This kind of interference can lead to abnormal I/O behavior, reduced measurement accuracy, and even component damage. In systems with poor isolation, signals may interfere with each other, causing data corruption, logical errors, or system crashes. Many cases of PLC failure are attributed to signal line interference, making it a critical concern in industrial applications. (5) Grounding plays a crucial role in improving the electromagnetic compatibility (EMC) of electronic systems. Proper grounding helps suppress electromagnetic interference and protect against external disturbances. However, incorrect grounding can introduce serious issues, such as ground loops and voltage differences between grounding points, which can disrupt the normal operation of the PLC system. The PLC system's grounding includes system ground, shield ground, AC ground, and protection ground. If not properly managed, potential differences between these grounding points can create currents that interfere with the system’s logic and analog circuits. For example, if a cable’s shielding layer is grounded at both ends, a potential difference can cause current to flow through the shield, leading to additional interference. This can be especially problematic during events like lightning strikes, when ground currents increase significantly. (6) Internal electromagnetic interference within the PLC system arises from interactions between internal components, such as logic and analog circuits, and their respective grounds. This type of interference is part of the manufacturer’s design considerations and is generally difficult to modify at the application level. While it’s complex, it’s important to choose a PLC system with strong EMC performance and consider testing to ensure reliability under real-world conditions. Gaming Laptop Used,Lenovo Legion Second Hand,Used Lenovo Legion,Lenovo Legion 5 Second Hand Guangzhou Panda Electronic Technology Co., LTD , https://www.panda-3c.com