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Introduction Of POE Camera

POE (Power Over Ethernet) refers to some IP-based terminals (such as IP phones, WLAN access points APs, network cameras) without any changes to the existing Ethernet Cat.5 cabling infrastructure. When transmitting data signals, it can also provide DC power for such devices. It is a switch that supports Power over Ethernet.


Introduction to POE switches

The POE switch port supports output power up to 15.4W or 30W, conforms to the IEEE802.3af/802.3at standard, and supplies power to standard POE terminal equipment through the power supply of the network cable, eliminating the need for additional power wiring. According to the IEEE802.3atPOE switch, the port output power can reach 30W, and the power available to the powered device is 25.4W. Generally speaking, the POE switch is a switch that supports the power supply of the network cable, which can not only realize the data transmission function of the ordinary switch but also simultaneously Power the network terminal.

POE (Power Over Ethernet) refers to some IP-based terminals (such as IP phones, WLAN access points APs, network cameras) without any changes to the existing Ethernet Cat.5 cabling infrastructure. While transmitting data signals, it can also provide DC power for such devices. POE technology can ensure the normal operation of existing networks while minimizing costs while ensuring the security of existing structured cabling.


International standard

POE is also known as POL (Power over LAN) or Active Ethernet, and is sometimes referred to as Power over Ethernet. This is the simultaneous transmission of data using existing standard Ethernet transmission cables. The latest standard specification for electrical power and maintains compatibility with existing Ethernet systems and users. The IEEE 802.3af standard is a new standard based on the Power over Ethernet (PoE) system. It adds the standard for direct power supply through the network cable based on IEEE 802.3. It is an extension of the existing Ethernet standard and the first international standard for power distribution. standard.

The IEEE began to develop the standard in 1999. The first vendors to participate were 3Com, Intel, PowerDsine, Nortel, Mitel and National Semiconductor. However, the shortcomings of this standard have always restricted the expansion of the market. Until June 2003, the IEEE approved the 802.3af standard, which specifies power detection and control issues in remote systems and provides access to IP phones, security systems, and wireless LANs over Ethernet cables to routers, switches, and hubs. The way in which devices such as points are powered is specified. The development of IEEE 802.3af includes the efforts of many corporate experts, which also allows the standard to be tested in all aspects.

The IEEE 802.3at standard was established in 2005 and was promulgated in 2009. The output power of the 802.3at standard can reach 30W, and the available power of the power receiving end is 25.5W.

The IEEE 802.3 Working Group and the Alliance of Manufacturers introduced POH-POWER OVER HDBASET in the end of 2012.

With the current 4-Pair four-pair technology, bilateral power supply can reach 60-100W power, which can be achieved with Category 5 or Category 6. The application is powered by high-definition video to 42" LED TVs, with the new 2010 US regulations for 42" LED TVs requiring less than 70W.

In the domestic production of 4-Pair four pairs of lines for fewer electrodes, so prospective operators should have POE+ upgrade to POH technology as soon as possible


work process

When a POE switch is deployed in a network, the POE switch works as follows:

Detection: At first, the poe switch outputs a small voltage on the port until it detects that the cable terminal is connected to a powered device that supports the IEEE802.3af standard.

PD end device classification: After detecting the power receiving device PD, the poe switch may classify the PD device and evaluate the power loss required by the PD device.

Start of power supply: During a configurable time (typically less than 15μs), the poe switch begins to supply power from the low voltage to the PD device until 48V DC power is supplied.

Power supply: Provides stable and reliable 48V DC power for PD devices, which can meet the power consumption of PD devices not exceeding 15.4W.

Power failure: If the PD device is disconnected from the network, the poe switch will stop powering the PD device quickly (usually within 300 to 400 ms) and repeat the detection process to detect whether the cable terminal is connected to the PD device.

A complete POE system includes two parts: a power supply unit (PSE, Power Sourcing Equipment) and a power source equipment (PD, Power Device). The poe switch is a type of PSE equipment. The PSE device is a device that powers Ethernet client devices and is the administrator of the entire POE Power over Ethernet process. The PD device is a PSE load that receives power, that is, the client of the POE system.


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