plc grounding method

PLC connection belongs to the single-point connection method of low-voltage electrical equipment.
The single-point connection methods of low-voltage electrical equipment can be divided into: series single-point connection, parallel single-point connection, and multi-branch single-point connection.
Serial single-point connection: that is, the first connection method. Connection method: Connect multiple low-voltage electrical equipment terminals to the same wire nearby, and then connect this wire to the connecting device. The advantage of this connection method is that it saves manpower and material resources; and the disadvantage is that when the public wiring breaks, a device in the connection system leaks electricity, which will cause voltage to appear on the casings of other devices, posing a threat to personnel safety.
A wire is drawn out from the spare connection terminal, and then these several wires are connected to the connection device at the same time. The advantage of this connection method: when one of the devices in the connection system is disconnected, it will not cause voltage to appear on the casing of other devices, which is good for personal safety. The imperfection of this connection method: electronic equipment or other electrical equipment highly sensitive to high-frequency interference, high-frequency interference from other equipment (such as inverters, intermediate frequency furnaces and other thyristor converter devices) will be connected from the common point input, resulting in abnormal operation of the equipment.
Multi-branch single-point connection: that is, the third connection method. Connection method: Connect each terminal of equipment to the connection device separately. The difference between the connection method and the second connection method: the equipment has a separate connection body (change: directly connect to the closest device (connection source) to the connection body, and the distance on the electrical connection circuit of each device is relatively far (for example, more than 50 meters) )). This effectively avoids mutual electromagnetic interference between devices. However, this connection method is time-consuming and laborious, and it is not necessarily good to connect the source alone.
In normal construction, the PLC connection method generally adopts the second connection method. As for electromagnetic interference: there are multiple high-power inverters in the cabinet, and a single-phase power filter can be installed at the front end of the PLC power supply. .
In general design, a power filter is installed at the front end of the PLC near the frequency converter.
After doing this, there will be no conflict with lightning protection.
How to deal with the problem of DC and AC connection is better to separate and connect to the same point, whether digital and analog can be the same point, remember that the teacher seemed to say to separate them in school
DC and AC equipment are not affected much by interference , can be connected together – the DC and AC circuits are connected for some reason, and they are in the same loop (connected to a part of the loop)), will cause equipment damage. Someone once connected the AC220V power supply to the DC24V circuit, but the equipment still works normally.
It is recommended to separate digital and analog (the power supply voltage of your low-voltage electrical equipment is tens of volts), digital circuits are at the level of plus or minus 5V, 12V, and 24V, and are easily disturbed. Once an external abnormal voltage is connected in series, it is very likely to cause damage Equipment damage.