The current is “injected” into the cabling at the level of the patch bay. This can be done through LAN/WAN switches”end-span” which integrate power supply circuits. If you do not want to replace your existing LAN switches or if you only want to power certain network segments, panels or injectors can be added in the middle of the loop (mid-span), that is to say between the switch and the powered device. Powered devices must also be PoE Lighting compatible. Many PoE-enabled switches also incorporate power management features, allowing PoE-powered hardware to be powered down or cold restarted remotely. An ideal solution for remote administration applications where certain computer equipment such as servers or routers must be cold restarted in order to be repaired.
When a powered PoE device is turned on, it informs the power supply hardware (whether end-span or mid-span) that it is ready to receive power through the Ethernet cable. Fully IEEE PoE compliant hardware will be able to receive power either through the data lines or through the unused pins of the Ethernet interface. In this area, network administrators should exercise caution, as some powered devices sold as compliant with IEEE PoE standards are limited in that they only accept power from mid-span power sources through the unused pairs. Mid-span injectors do not always check if the target device needs power and therefore may damage devices that do not require power.
In order to protect the supply source equipment from input current peaks, which sometimes occur during start-up, it is important that the equipment In order to protect the supplied equipment from input current peaks, which sometimes occur during start-up, it is It is important that the materials supplied have a protection system against these peaks. The equipment, thus protected, begins by claiming a limited voltage in order to protect its current supply equipment (PSE), then switches to full power, up to a maximum of 100 watts.
Beyond 100 meters of poe lighting
For remote devices that need to receive power and data, but are located beyond the 100m reach of copper links, network managers have several options. They can add a remote data closet, use LAN expanders that convert Ethernet links to DSL, use UTP over coaxial converters, or install a wireless solution. Or, they can leverage the benefits of optical cables to extend network reach.
Fiber extends network reach to 160 km per link without deterioration, unlike copper links. LAN extenders can extend the network range to 10 km, but all links longer than 100 m are subject to considerable slowdowns. Thus, the nominal data rate of 100 Mbit/s is likely to be reduced to only 2.3 Mbit/s. In addition, the fiber also offers advantages from a safety point of view. It does not generate electromagnetic emissions and is very difficult to hack. Finally, since it is not subject to electrical interference, or loss of data due to atmospheric conditions, fiber is extremely reliable.
The fiber link can start from a data cabinet located near a power outlet. A PoE media converter can be powered by either AC or DC power. The power source and the fiber cable are connected to the media converter. A 100 m copper (UTP or STP cable) Ethernet link can be used to reach the powered device. The PoE media converter converts data from fiber to copper, bringing all the power and data needed to the powered device.
When you need to extend Ethernet services beyond the general limits of IEEE 802.3 (100m) and the cost of fiber cabling is prohibitive, Ethernet extenders are the ideal solution. Ethernet Extenders seamlessly extend 10/100/1000 Ethernet connections over copper cabling. Use twisted pair (CAT5/6/7), coaxial, or any existing copper wiring previously used in alarm circuits, E1/T1 circuits, RS-232, RS-422, RS-485, and CCTV applications and CATV. A PoE Ethernet Extender can be used as PD or PSE.
Single signature and double signature PDs
The 802.3bt standard or LED Lighting control introduced two new powered device topologies: single signature and dual signature. Single Signature devices share the same detection and classification signatures and maintain the power signature between device pairs. They are generally used for single load applications. Dual Signature Powered Devices allow independent detection and classification signatures, and maintain the power signature between pairs of devices. They are ideal for multi-load applications, such as surveillance cameras with heaters. Today, the deployment of dual-signature PDs can deliver 51W to PDs. However, newer PD deployments tend to use single signature PDs to save on overall product cost and take advantage of higher power, at 71 W. It is important to determine if the Power Supply Equipment (PSE) supports single signatures, dual signatures, or both when planning a deployment. A PSE device supporting both options will not need to be replaced during a future replacement of powered devices. duplicate signatures or both when planning a deployment. A PSE device supporting both options will not need to be replaced during a future replacement of powered devices. duplicate signatures or both when planning a deployment. A PSE device supporting both options will not need to be replaced during a future replacement of powered devices.
The advantages of PoE technology are:
- Only one set of cables to connect to Ethernet hardware, simplifying installation and saving space.
- No additional costs for hiring an electrician, or waiting for their availability – saving time and money.
- Equipment can be easily moved as long as it can be connected to a LAN cable – ensuring minimal downtime.
- Safer, since there is no need to run power lines anywhere.
- An inverter is enough to guarantee the supply of equipment even in the event of a general cut.
- Devices can be shut down or cold restarted remotely – no need for a reset or power switch.
