The power of Power-over-Ethernet

In addition to increasing power delivery, four-pair powering also uses lower current, which extends PoE technology’s reach by reducing losses on the cable.  For instance, if Type 1 devices are used over four pairs with worst-case Cat5 cables, the resistance is dramatically lower than that of Cat3 cables. Cat3 cables have a loop resistance of 20ohm for 100m, while Cat5 cables with 4-pairs have a resistance of only 6.25ohm for 100m.
This means PoE could power PDs over three times longer distances using four-pair powering, or up to 320m for devices that consume 12.95W.  Of course, this approach only works if the physical-layer (PHY) device being used to transmit data also supports these long distances. For Type 2 devices, as long as the input voltage to a PD is 37V or higher and the current is below 600mA, the PD will work with cables up to 200 meters, with identical performance since the PSE monitors the load of the cable and PD as a single entity.

Reach
IT professionals have options for even longer reach.  By combining four-pair powering with PoE extender technology, IT professionals can more than double the distance PDs can be located from network PSEs.  PoE extenders can increase reach by as much as 100 additional meters, without reliance on specific PHY implementations.

In addition to boosting power and the distance over which PDs can be powered, the latest PoE technology also improves network-deployment flexibility, boosts overall network power efficiency and simplifies maintenance.  Power capacity can be added to the network in as little as one-port increments, and each PD can also be monitored and managed remotely using the midspan’s SNMP power modules, Web-based power monitoring and management, and other flexible power-management features.  Midspans also enable centralized control of multi-site or multi-building installations, and support immediate alert (e.g. E911) and response if IP phone status changes.

The latest PoE midspan technology delivers more power over longer distances with greater flexibility and energy efficiency, while also providing smart power-management capabilities that simplify monitoring and maintenance. High-power PoE midspans can be used to improve network performance while future-proofing the network for optimal effectiveness over the life of the installation