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Seven common problems with POE power supply(on)

Dec. 17, 2019

In recent years, the development of POE power supply technology has grown from 100M to Gigabit to full Gigabit. With a series of advantages such as simplifying the installation and deployment of electrical equipment, energy saving, and safety, POE power supply has many applications in scenarios such as wireless coverage, security monitoring, and smart grids. However, most users still have many questions about POE power supply, and there are seven major problems. POE suppliers will take you to understand this issue.

First, how to choose security monitoring and wireless coverage POE Switch

There are many types of POE switches, from 100M to Gigabit to full Gigabit. There are also differences between non-network management and network management types, and the difference in the number of different ports. To choose the right switch, you need to comprehensively consider . Take the project that requires high-definition monitoring as an example.

Step 1: Select a standard POE switch (see Question 2 for reasons)

Step 2: Select a 100M or Gigabit switch

In the actual scheme, it is necessary to select the number of cameras, camera resolution, bit rate, and frame number. Users can use the tools to calculate the required bandwidth to select a suitable POE switch.

Step 3: Choose AF or at standard POE switch

Select according to the power of the monitoring equipment. For example, using a well-known brand camera, power 12W max, in this case, you need to choose AF standard switch. The power of a high-definition dome camera is 30W max. In this case, an at standard switch is needed.

Step 4: Select the number of ports on the switch

POE switches can be divided into 4 ports, 8 ports, 16 ports, and 24 ports according to the number of ports, which can comprehensively monitor the power, quantity, location of the equipment, the power supply of the switch and the price selection.

Second, why must the selection criteria POE switch power supply?

First, the difference between a standard POE switch and a non-standard POE switch needs to be clarified. The standard POE power supply switch has a POE control chip inside, and it has a detection function before power supply. After the device is connected, the POE power supply will send a signal to the network to detect whether the terminals in the network are PD devices that support POE power supply.

Non-standard POE products are high-powered network cable power supply devices, which supply power as soon as they are powered on. There is no detection step. No matter whether the terminal is a POE powered device, it is very easy to burn the access device.

After the power is turned on, the switch will automatically detect the powered device. If it detects that the non-POE powered device is connected, it will automatically stop the power supply. The detection process is as follows. Therefore, you must use a standard POE switch to supply power.

POE Switch

POE Switch

Third, how to distinguish POE measured with a multimeter and non-standard POE

How to distinguish between standard industrial POE and non-standard POE is simple, just use a multimeter to measure. Methods as below:

Start the device, adjust the multimeter to the voltage measurement position, and use the two multimeter pens to touch the PSE device power pin (usually 1/2, 3/6 or 4/5, 7/8 of the RJ45 port) ), If a device with a stable output of 48V or other voltage values (12V, 24V, etc.) is measured, it is a non-standard product. Because in this process, the PSE does not detect the power receiving equipment (here, the multimeter), and directly uses 48V or other voltage values to supply power.

Conversely, if the voltage cannot be measured, the multimeter's hands jump between 2 ~ 10V, it is a standard POE. Because at this stage, the PSE is detecting the PD end (here is the multimeter), and the multimeter is not a legitimate PD. The PSE will not supply power and no stable voltage will be generated.