|
Implementation of this technology simplifies the network infrastructure significantly, eliminating the need of power cables for all the IP-devices as specific devices may be powered from a central location.
The most important feature of the standard is that Power over Ethernet is completely compatible with existing Ethernet switches and networked devices. Because the Power Sourcing Equipment (PSE) tests whether a networked device is PoE-capable, power is never transmitted unless a Powered Device is at the other end of the cable. It also continues to monitor the channel. If the Powered Device does not draw a minimum current, perhaps because it has been unplugged or physically turned off, the PSE shuts down the power to that port. Optionally, the standard permits Powered Devices to signal to a PSE how much power they require.
Network devices which can accept the injected DC power directly from the Category 5 cable through their network connection are considered to be “PoE Compatible” or “Active Ethernet Compatible”.
Devices which are not PoE Compatible can be converted to Power-over-Ethernet by way of an “Active Ethernet Splitter (also known as a DC “Picker” or “Tap”). These devices take the DC voltage that has been injected into the Category 5 cable, by the injector, and make it available to the connected device via a conventional DC power socket.
Two basic types of “Active Ethernet Splitters” are available; passive and regulated.
A passive Active Ethernet Splitter simply takes the voltage from the Category 5 cable and directs it to the device for direct connection.
A regulated Active Ethernet Splitter takes the voltage from the Category 5 cable and converts it to a different voltage. Several standard regulated voltages are available such as, 12VDC, 6VDC and 5VDC. This allows a wide range of non-PoE devices to be powered through a Category 5 cable.
Using the same LAN infrastructure, and without making any modifications to the end points, installed devices, such as Wireless LAN access points and Network Cameras become Power over Ethernet enabled when connected to the active splitter.
Standards
Power over Ethernet equipment has been available for a number of years, so what has changed? The most important change is that a stable, official specification now exists that the vendors can build to. The US based IEEE (Institute of Electrical and Electronic Engineers) approved the standard for Power over Ethernet products in June 2003. The 803.af-2003 standard ensures that:
|
