With the widespread use of electrical control cabinets in the industry, many people now have some misunderstandings about the layout. The following editor will take you to understand several precautions for the layout of electrical control cabinets.
1. Make all equipment in the electrical control cabinet well grounded, and use short and thick grounding wires to connect to the common grounding point or grounding busbar. Any control equipment (such as PLC) connected to the inverter should be grounded together with the inverter, and short and thick wires should be used for grounding. Flat conductors (such as metal mesh) because of their low impedance at high frequencies.
2. Let the contactor in the electrical control cabinet have an arc extinguishing function. The AC contactor uses an R-C suppressor, and the DC contactor uses a "flywheel" diode, which is installed in the winding. The use of a varistor suppressor is also very effective.
3. Electrical control cabinets, low-voltage devices, relays and contactors should be protected by fuses; when the inverter is connected to the motor for more than 100m, the inverter power supply capacity is greater than 600kW/A, or the power supply capacity is greater than 10 times the inverter capacity, it is recommended to add input and output reactors.
4. If the equipment works in a noise-sensitive environment, an EMC filter can be used to reduce radiated interference. At the same time, for the best effect, make good contact between the filter and the mounting plate.
5. In order to effectively suppress the radiation and conduction of electromagnetic waves, the motor cable of the inverter needs to use a shielded cable, and the conductivity of the shielding layer needs to be at least 1/10 of the conductivity of each phase conductor core. The electrical control cabinet should be equipped with a neutral line group and a protective ground line group (PE) respectively. The grounding rod group and PE conductive need to be connected to the beam (copper rod to copper rod connection). They need to be directly opposite the cable gland. The grounding rod group should also be connected to the protection circuit (grounding rod) through another cable. The shielded busbar is used to make a reliable shield connection for each cable. A large area metal-to-metal connection is achieved through the beam.
6. The motor cable should be laid separately from other control cables, with a minimum distance of 500mm. At the same time, the motor cable and the control cable should be avoided from being laid in parallel for a long distance. If the control cable and the power cable cross, they should be crossed at an angle of 90° as much as possible. At the same time, the shielding layers of the motor cable and the control cable need to be fixed to the mounting plate with suitable clips.
7. The electrical control cabinet should be equipped with a neutral line group and a protective ground line group (PE) respectively. The grounding rod group and the PE conductive need to be connected to the beam (copper rod to copper rod connection). They need to be directly opposite the cable gland. The grounding rod group should also be connected to the protection circuit (grounding rod) through another cable. The shielding busbar is used to make a reliable shield connection for each cable. A large area of metal-to-metal connection is achieved through the beam.
8. The operation panel with a display cannot be installed near cables and equipment with coils, such as power cables, contactors, relays, solenoid valves, transformers, etc. Because they will generate strong magnetic fields and affect the measurement accuracy of instruments and meters.
9. According to the protection level of the equipment in the control cabinet, the dust and moisture-proof functions of the control cabinet need to be considered. Commonly used equipment mainly includes: air conditioners, fans, heat exchangers and anti-condensation heaters. At the same time, equipment of different powers should be appropriately selected according to the size of the cabinet. The selection of the fan mainly considers the normal working temperature in the cabinet and the higher ambient temperature outside the cabinet to obtain the temperature difference, the ventilation volume of the fan and the air volume in the cabinet. After the three data of temperature difference, ventilation volume and air volume are known, the time of ventilation in the cabinet is obtained, and then the actual required ventilation volume is calculated by temperature difference. In order to select the actual fan. As the temperature drops at night, condensation water will be generated and attached to the circuit board in the cabinet, so it is necessary to select the corresponding anti-condensation heater to maintain the temperature in the cabinet.
10. Basic requirements for inverter installation. The inverter is preferably installed in the middle of the control cabinet. The inverter should be installed vertically. Large devices that may block the exhaust and air intake should be avoided directly above and below; the distance between the upper and lower edges of the inverter, the distance between the top and bottom of the electrical control cabinet, or the smaller distance between the diaphragm and the large equipment to be installed should be greater than 150mm; if special users need to remove the keyboard during use, the keyboard hole of the inverter panel needs to be strictly sealed with tape or replaced with a false panel to prevent a large amount of dust from entering the inverter.
The above is the relevant information about electrical control cabinets that I have sorted out for you. Jiangsu Xukong Technology Co., Ltd. is a professional industrial control equipment manufacturer. It has been undertaking automatic control systems, electrical automation design, and electrical engineering transformation for many years. Its business involves machinery manufacturing, power systems, water treatment, casting, metallurgy, environmental protection and light industry. We have rich experience and reasonable prices. If you need anything, please feel free to call us.