PoE is known as Power over Ethernet. It is a technology that can transmit power and data transmission to a powered device over a twisted-pair cable in Ethernet, which can also be said to support a network cable to provide power and data transmission to a PoE-enabled powered device (abbreviated as PD) at the same time. However, what is the PoE power supply standards?
What are the PoE power supply standards?
To standardize and promote the development of PoE applications, in June 2003, the IEEE 802.3 working group developed the IEEE 802.3af standard as an extension of the Ethernet standard, with detailed provisions for power supply, transmission, and reception of network power.
The IEEE 802.3af standard is a new standard based on the Power over Ethernet system PoE, which is based on IEEE 802.3 and adds standards related to direct power supply through the network cable, an extension of the existing Ethernet standard and the first international standard on power distribution.
The IEEE began developing the standard in 1999, and the first vendors involved were 3Com, Intel, PowerDsine, Nortel, Mitel, and National Semiconductor; however, the shortcomings of the standard have been limiting the expansion of the market. It wasn’t until June 2003 that IEEE approved the 802. 3af standard specifies power detection and control matters in remote systems and how routers, switches, and hubs power devices such as IP phones, security systems, and wireless LAN access points over Ethernet cables. Efforts which has allowed the standard to be tested in various areas.
In October 2009, the IEEE 802.3at standard was created in response to the demand for high-power terminals, providing more significant power supply requirements to meet new demands based on compatibility with the 802.3af standard.
What are PoE parameters?
A complete PoE system includes Power Sourcing Equipment (PSE, Power Sourcing Equipment) and Powered Device (PD, Powered Device). PSE equipment is the power supply for Ethernet client devices and the entire PoE Power over Ethernet process manager. The PD device is the PSE load that receives power, i.e., the client devices of the PoE system, such as IP phones, network security cameras, APs, and many other Ethernet devices such as PDAs or cell phone chargers (in fact, any device with a power not exceeding 13W can get the corresponding ability from the RJ45 socket). The two are based on the IEEE 802.3af standard to establish information about the connection of the device PD at the receiving end, the type of device, power consumption level, etc., and based on this PSE through the Ethernet to the PD power supply.
PoE standard power supply system of the main power supply characteristics parameters as below.
- The voltage is between 44 and 57V, the typical value of 48V. 2.
- the maximum allowable current is 550mA; the maximum start-up current is 500mA.
- typical operating current is 10–350mA, overload detection current is 350–500mA.
- Under no-load conditions, the maximum required current is 5mA.
- for PD equipment to provide 3.84 ~ 12.95W three levels of electrical power request, the maximum does not exceed 13W. (Note that PD classification 0 and classification 4 is not shown and should not be used.
Final Words
The above is the PoE power supply standard and PoE power supply parameters of a typical Power over Ethernet system. Ethernet switch equipment is reserved in the wiring closet, and a power supply hub is used to provide power to the twisted-pair cables of the LAN. At the end of the twisted pair, this power is used to drive phones, wireless access points, cameras, and other devices. To avoid power down, an optional UPS power is available.
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