In order to ensure that the CNC system and CNC machine tools can work normally, especially in the case of China's power grid quality fluctuations, the electromagnetic compatibility (EMC) design of the CNC system is more important. Electromagnetic compatibility (EMC) refers to the ability of a numerical control system to function properly in its electromagnetic environment without posing unacceptable electromagnetic disturbances to anything in the environment. Now with the Huazhong CNC system, let's talk about the electromagnetic compatibility (EMC) design of the CNC system. 1 CNC system electromagnetic compatibility design requirements In order to ensure that the CNC system is used in the industrial environment where the electromagnetic environment is harsh, long-term and continuous use, the system must meet the electromagnetic compatibility requirements in JB/T 8832-2001 "General technical conditions of machine tool numerical control system". 1.1 Electrostatic discharge immunity test When the CNC system is running, according to the provisions of GB/T 17626.2, the electrostatic discharge test is performed between all parts frequently touched by the operator and the protective earthing terminal (PE). The contact discharge voltage is 6kV, the air discharge voltage is 8kV, and the numerical control system in the test Can run normally. 1.2 Electrical fast transient burst immunity test When the CNC system is running, according to the provisions of GB/T 1762*, a peak 2kV, repetition frequency 5kHz pulse group is added between the AC power supply terminal and the protection ground terminal (PE) for 1 min; in I/O signals, data and The control port cable is connected to the peak 1kV with a coupling clip and the repetition frequency is 5kHz pulse group for 1min. The CNC system can operate normally during the test. 1.3 Surge (impact) immunity test When the CNC system is running, according to the provisions of GB/T 17626.5, a surge (shock) voltage with a peak value of 1kV is superimposed between the AC input power phase lines; a peak is superimposed between the AC input power phase line and the protective ground (PE). It is a surge (shock) voltage of 2kV. The surge (shock) repetition rate is 1 time/min and the polarity is positive/negative. The positive/negative tests are carried out 5 times each time, and the numerical control system should be able to operate normally. 1.4 Voltage sag and short-term interruption immunity test When the CNC system is running, according to the provisions of GB/T 17626.11, the voltage amplitude drops to 70% of the rated value at any time of the AC input power supply, the duration is 500ms, and the interval between successive landings is 10s; according to 4.3 in GB/T 5226.1-1996 The regulation is interrupted for 3ms when the AC input power supply voltage is short at any time, and the interval between successive interruptions is 10s. The voltage sag and short-term interruption are performed three times each, and the CNC system should be able to operate normally. 2 Shielding technology in electromagnetic system design of numerical control system In the CNC machine tool system, there are high-voltage, high-current high-power equipment, low-voltage, low-current control and signal processing equipment and sensors and other weak electrical equipment. The strong electromagnetic interference generated during the working process of the strong electric equipment poses a great threat to the normal operation of the weak electric equipment. In addition, the electromagnetic environment at the production site is harsh, and various power loads, power supply systems, and disturbances in the atmosphere outside the system may cause interference to the control of weak electrical equipment, causing them to fail to work properly, thereby causing the entire system to collapse. In order to ensure the normal operation of the numerical control system, the shielding technology is one of the three technical measures commonly used in the electromagnetic compatibility design of numerical control systems. Shielding technology is used to suppress the propagation of electromagnetic noise along the space, that is, to cut off the transmission path of radiated electromagnetic noise. The metal or magnetic material is usually used to surround the area to be shielded, so that the "field" inside and outside the shield is isolated from each other. Shielding can be divided into electric field shielding, magnetic field shielding and electromagnetic field shielding according to its mechanism. 2.1 Electric field shielding When the noise source is high voltage and small current, the radiation field mainly acts as an electric field, and the electric field shielding is to suppress the interference between the noise source and the sensitive device due to the presence of electric field coupling. 2.1.1 Mechanism of electric field shielding 2.1.2 Main points of electric field shielding design Electric field shielding design should be considered: First, the strong electrical equipment (servo drive, frequency converter, stepper drive, switching power supply, motor) in the system is reliably grounded to achieve active shielding; second, sensitive equipment (such as numerical control devices, etc.) The outer casing should be grounded reliably to achieve passive shielding. 3. The distance between the strong electrical equipment and the sensitive equipment is as far as possible. Generally, in the electric cabinet, the strong and weak electrical equipment should keep the distance of 30cm or more as much as possible, and the minimum distance is 10cm. 4. High voltage The high-current power line and the signal line should be separated. For example, each of them should use separate line slots. The distance should be kept as much as 30cm or more, and the minimum distance is 5~7.5cm. At the same time, parallel lines should be avoided as much as possible. Bundle with the signal line; 5. The signal line should be as close as possible to the ground line (or ground plane) or surrounded by the ground line; 6. The shielded cable can both passively shield the electric field and act as an active shielding. Is the shield grounded. 2.2 Magnetic field shielding When the noise source has low voltage and large current performance, its radiation field mainly acts as a magnetic field, and the magnetic field shielding is to suppress the interference between the noise source and the sensitive device due to the magnetic field coupling. 3 Liter Oil Deep Fryer,3L Capacity Deep Fryer,Electrical Deep Fryer,Stainless Steel Deep Fryer Shaoxing Haoda Electrical Appliance Co.,Ltd , https://www.zjhaoda.com