The internal layout and wiring of an electrical control cabinet play a crucial role in the performance and reliability of a CNC system. A well-planned design not only simplifies production and maintenance but also significantly improves the stability of the system. Here are some key considerations when designing the layout and wiring:
1. Handling of 220V Power Supply Lines: High-power equipment can cause serious power grid pollution, leading to voltage fluctuations and surges. In China, where the power grid has high internal resistance and is prone to noise, even with voltage regulation measures, external interference can still affect the system. According to statistics, over 90% of system malfunctions, such as CPU failures and data loss, are caused by power supply issues like short circuits, under-voltage, over-voltage, and noise intrusion. Therefore, anti-interference design must focus on power supply management.
- Power cables should be kept away from other cables in the system. Install filters near the power entry point to prevent external noise from entering the cabinet.
- Filters should be placed as close as possible to the power input socket. The incoming and outgoing lines should be routed separately and not run parallel. It’s better to have an 180° angle between them. The filter's output line should be kept far from the input line to avoid re-coupling of interference.
- Important components, such as the AC power supply of the CNC system, should use low-pass filters to reduce high-frequency interference. If possible, separate filters should be used for the servo motor driver, inverter, computer, and control circuit. This helps suppress both external and internal interferences. However, it’s essential to clearly define the input and output of the filter, or it may not function properly.
- Strong and weak signal lines should never be in the same conduit or placed too close together to minimize electromagnetic interference.
2. Grounding and Shielding Considerations: Proper grounding is vital for redirecting interference away from sensitive equipment. However, improper grounding can introduce more problems than it solves. Shielding protects internal circuits by conducting interference to ground through the shield. To ensure effective shielding, the overlap between the shield and the ground should be maximized to reduce impedance.
- The control cabinet should be made of conductive metal plates. A one-piece structure or welding is recommended to maintain electromagnetic consistency.
- The mounting plate inside the cabinet should also be made of conductive material to improve grounding performance.
- High-voltage equipment, such as filters, inverters, switching power supplies, and motor drives, should be mounted on a conductive metal plate and properly grounded.
- All shielded cables should enter the control cabinet with their shields grounded. Proper grounding methods are essential to prevent interference from affecting the system.
By following these guidelines, you can ensure that your electrical control cabinet is not only efficient and reliable but also resilient against various types of electrical interference. A well-designed system will save time, reduce downtime, and improve overall performance in industrial applications.
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Xuzhou Jiuli Electronics Co., Ltd , https://www.xzjiulielectronic.com