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Why Can't the Power Supplied By the Poe Switch Exceed 30w?

With the rapid development of the Internet of Things technology, terminals that need to provide network services are becoming more and more abundant. It is becoming more and more difficult to supply power to a variety of smart terminals using traditional high-power methods. Power over Ethernet (PoE for short) The popularity of technology is solving the power supply problems of various intelligent terminals one by one. At present, PoE technology has been extended from traditional application scenarios such as WLAN, network monitoring, and IP telephony to new retail, IoT (Internet of Things, Internet of Things), and smart cities. It is widely used, with low cost, convenient construction, and power supply. Stability and high operation and maintenance efficiency.

The common PoE switch has a single port power supply of 15.4W and 30W, and the power supply voltage is generally 48V. When choosing a waterproof PoE switch to supply power to network equipment, the total power supply is very important The indicator is that the power is low and the device cannot work. So some people are wondering, why can't the single port power be made above 30W, such as 50W, 60W or 100W? Or increase the power supply voltage to 60V, 100V, etc. To answer this question, you need to understand the principle of PoE power supply.

Waterproof Poe Switch

Waterproof Poe Switch

PoE power supply is realized through network cables, which means that power needs to be transmitted in the network cables. We know that network cables are generally used to transmit data signals. If power signals are transmitted, there is a problem of resistance and resistance. If the voltage is set to 100V, the current transmitted through the network cable will be very high, exceeding the capacity of the network cable, and will cause many hidden dangers. Since the voltage cannot be so high and the current cannot be so high, the power supply naturally cannot be so high.

When the PoE power supply, there are both data signals and power signals in the network cable. In order not to affect each other and to ensure the best power transmission effect, the single-port power supply of the relevant PoE-powered equipment specified by the industry cannot exceed 30W. It is the IEEE 802.3at standard released in 2009, which can provide a maximum of 30W power through CAT-5 or higher level cables.

With the development of science and technology and new security requirements, IEEE 802.3bt was formally approved in September 2018. This standard was born to provide the demand for higher power terminals. On the basis of compatibility with 802.3af and 802.3at, it can complete the highest The end power supply and data transmission of less than 90W break through the limitation of PoE + power supply of 30W. (Note: 802.3bt has been approved but has not yet been officially released, nor has it been officially named. Currently, names such as HPoE, PoE ++, PoH, UPoE are commonly used.)

With more power, developers can easily add more functions and upgrade existing products to meet the power supply requirements of high-power terminals in systems such as surveillance, access control, information release, parking, and even laptops, TVs, etc. .

Compared with the 802.3at (PoE +) standard, 802.3bt has two new power supply types, corresponding to 60W and 90W output power. The power selectable by the PSE end is more selective, and the corresponding PSE end power is selected according to the needs of the PD.

Nowadays, PoE technology has been widely used in smart cities, IoT and other industries. It is believed that PoE technology will have greater development and breakthroughs in the near future. With the formal approval of 802.3bt (expected to be officially released in 2019), higher power terminals It will be widely used soon, which will help the rapid development of the IoT industry.