UNIPOE IOT Technology Co.,Ltd.
News Banner

EFT Problems of the Industrial Grade Switch

1.Problem Description for the Product EMC

A certain product is an industrial switch product with 24V DC input. The external communication interface has a 100-mega optical fiber interface and a 100-mega Ethernet interface, which uses a dual 24V DC input and only has one connection in the experiment. The product requires 4KV, 5K/100KHz interference frequency in EFT test. The criterion is A. During the test process, data need to be transmitted, and no packet loss can occur in the middle. The phenomenon happening is the loss of the prototype in the test process.

Problem Analysis

The EFT test level of the power supply port of industrial grade switch is relatively high. At present, the power supply interface is three-stage common mode filter, and then it enters the single board through DC power module. Although it is a three-stage filter circuit, it may not be enough for such a harsh level. The structure of the prototype is very compact. In the internal structure, the power board is placed above the CPU board. It is likely to affect the CPU board and switch board through radiation interference. The whole prototype is made up of six metal plates. The overlap between metal panels is not good enough, which results in the loss of packets caused by the unobstructed release of interference on the digital ground of the motherboard.


Rectification measures

1. External filter is installed at the power input port.
Result: The number of lost packets has been greatly reduced and the overall situation has been greatly improved. In the latter optimization, the external filter can be removed and only the Y capacitor can be added on the power board.
2. The prototype has two grounding wires connected to the earth, one is the 5PIN input ground, while the other is the grounding stud of the prototype connected to the earth. And one of the grounding wires is not connected in the experiment.
Results: The number of lost packages increased significantly. It shows that the ground loop of the prototype has a great influence on the test results.
3. When the prototype is dismantled, it is found that the PGND on the power board passes through the stud in the upper right corner to the housing.
In rectification of the site, the screw hole is insulated from the stud on the basis of the external filter.
Result: no package lost.

The final rectification measures are to add the Y capacitance on the power supply and to the use power supply board insulate to be close to the screw of the CPU board.
conclusion
1. For the power port EFT interference processing, it is mainly in the power filter processing. On the basis of the current three-stage filter, only the Y capacitor can be added.
2. For the crust of PCB board, we must make a good plan to avoid the disturbing circuit path affecting the digital signal communication.

UNIPOE provides you with industrial grade switch. Welcome to choose and buy.

Related News
  • Management Switch PK Non-management Switch, who do you Support?

    Management Switch PK Non-management Switch, who do you Support?

    March 29, 2019Non-managed switches:Advantage1. Cheap price, save expenditure;2. Dense number of ports;3. Plug and play, fool operation, flexible deployment!Shortcoming1. Non-network management Industrial Ethernet s...view
  • Number of Devices a POE Switch Can Access

    Number of Devices a POE Switch Can Access

    October 10, 2018In general, the number of devices that a POE switch can access will be affected by several factors, including the power supply standard of the POE switch, the total power supply of the POE switch and ...view
  • Internet Switch 16 Port

    Internet Switch 16 Port

    August 2, 2018New energy-saving design to lead low carbon communicationIt uses no fan silent design to reduce the power consumption of the whole machine, at the same time, let you avoid the noise annoyance.It abide...view
  • How to Use and Select POE Powered Switches

    How to Use and Select POE Powered Switches

    July 15, 2019The poe powered switch is also equivalent to a power line. It supplies power to wireless AP, network telephone, network camera and other devices through the network line, which not only effectively so...view
  • Choosing Correct Manageable Network Switch

    Choosing Correct Manageable Network Switch

    July 21, 2018According to the 7 layer network model of OSI, the switches can be divided into layer 2 switch, layer 3 switch, layer 4 switch and so on, all the way to the layer 7 switch. The layer 2 switch based on...view
  • Common Categories and Setting Methods of Smart Network Switches

    Common Categories and Setting Methods of Smart Network Switches

    October 10, 2018Common categories24 port or 48 port Gigabit uplink 10/100M smart network switch16, 24, or 48 port full Gigabit smart network switchStacked 24 port or 48 port Gigabit uplink 10/100M smart network switc...view
  • TEL:+86-769-86001588(Ext. 122, 123)
  • EMAIL:info@unipoe.com
  • ADDRESS:11th Fl., BLDG. B1, Guangda WE Valley, Songshan Lake District, Dongguan, China