POE power supply is not make any changes in the existing Ethernet Cat 5 cabling infrastructure for IP-based terminal (such as IP telephones, wireless LAN access point AP, network cameras, etc.) to transfer data signal at the same time, but also for such equipment DC power supply technology. POE is also known as LAN-based power supply system (POL, Power over LAN) or Active Ethernet (Active Ethernet), sometimes also referred to as Power over Ethernet, which is the simultaneous transmission of data using the existing standard Ethernet transmission cable and electric power standards, and maintain compatibility with existing Ethernet system and user.
Standard UTP cable has four twisted pairs, but only used in l0M BASE-T and 100M BASE-T in two. IEEE80 2.3af allows two ways: application idle pin power supply pins 4 and 5 connected to the positive electrode, 7,8 pin connector for the negative. Application data when the foot-powered, the DC power is added at the midpoint of the transmit transformer does not affect the data transmission. In this way, off the assembly line on lines 1, 2, and 3 and 6 can be of either polarity. The standard does not allow the application of the above two cases. The power supply equipment PSE can provide a usage, but the power application equipment PD must be able to adapt to both cases. The standard requires that the power supply is 48V, 13W. The PD device provides 48V to low voltage conversion is easier, but at the same time should be 1500V insulated safety voltage. POE standard power supply system power supply characteristic parameters: 1. Voltage of 44 to 57V, the typical value of 48V. 2 allows a maximum current of 550mA, the maximum starting current of 500mA. 3 typical operating current of 10 to 350 mA, overload detection current 350 ~ 500mA. In no-load conditions, the greatest needs of current is 5mA. 3.84 to 12.95W five levels of electric power equipment for the PD request does not exceed 13W. POE power supply work process when arranged in a network PSE power supply terminal equipment, POE Power over Ethernet process is as follows. 1 detection, PSE device small port output voltage until it detects cable connected to a terminal supports the IEEE 802.3af standard receiving end equipment. PD-end equipment classification upon detection of Powered Device PD PSE device may be classified equipment for the PD and the power loss of the equipment needed to assess the PD. Power supply in a configurable time (generally less than 15μs) start-up period, PSE equipment from low voltage to the powered devices (PDs), until a 48V DC power supply. 4 reliable 48V DC power supply equipment for the PD to meet PD device does not cross the power consumption of 15.4W. 5 power if the PD is disconnected from the network, the PSE will quickly (usually in the 300 to 400 ms) stop-powered devices (PDs), and repeat the detection process is connected PD detection cable terminal equipment.
POE power supply benefits are the following:
Reduce costs: eliminates the need for cumbersome power supply wiring, not only eliminates the need for the construction of equipment supply and maintenance costs, such as power lines, sockets, pipes, etc., but also eliminates the need for expensive electrical costs, but also save the layout and installation power supply system the time required;
Deployment flexibility: the location of the equipment deployed unrestricted, do not have to go long enough to consider whether the power outlet, the AP terminal equipment easily fits in any remote location, such as ceilings, cut off the upper position;
Support 802.3at standard, single-port maximum power of up to 30W, while providing support for non-standard powered device, which greatly enhance the capacity of the network service access;
4 safe and reliable: power centralized power supply, convenient backup. The same time, the power supply device is connected UPS, once the main power input interrupt, but also to ensure the normal operation of the system;
Enhanced Management: SNMP PoE system, its remote monitoring and management of AP and IP cameras PD equipment.
Prospects: can be widely used in IP telephony, wireless AP (Access Point, Access Point), portable chargers, card readers, Webcam, data collection terminals, markets a wide range of broad application prospects.