Product category:
AC/DC Power Supplies
News Release from: Phihong Europe
Edited by the Electronicstalk Editorial
Team on 10 February 2006
Task force looks for more power over
Ethernet
Last month's meeting of the IEEE802.3at task force discussed achievable limits of two- and four-pair solutions for the new PoEPlus standard.
Phihong USA presented its proposals on achievable limits of two- and four-pair solutions at the 12th January meeting of the IEEE802.3at task force, along with several other member companies Based on these presentations, the task force concluded that the standard's objective of providing enough power for multiband access points and controllable security cameras can be met with a two-pair solution, which is lower in cost and simpler to implement compared with four-pair solutions
This article was originally published on Electronicstalk on 12 Mar 2004 at 8.00am (UK)
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Designated PoEPlus, the new standard will more than double the wattage available to powered devices.
"The specification is far from finalised but most members believe a source voltage from the PSE of 51-57V with up to 840mA is a reasonable expectation", said Keith Hopwood, Vice President of Marketing for Phihong USA.
"The drop per pair total in a worst case scenario of 100m cable and connectors is 12.5ohm, which would provide over 30W at the powered device".
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"The limiting factor is the temperature rise in bundled cabling", said Hopwood.
The cable working group is testing 196 cables bundled in a conduit and measuring the temperature rise in all the conductors when current runs through them.
The testing does not reflect a safety concern or fire hazard, but the cables will permanently deform above certain temperatures, causing data attenuation.
"At Phihong, we offer both two-pair and four-pair solutions, so we know the two-pair option is feasible", said Hopwood.
In addition, at the meeting, a group was formed to define a detailed classification proposal.
The new classification will not only give a much higher resolution of current required by the powered device but will also signal the powered device of the source power capability of the power sourcing equipment.
If implemented as a standard, PoEPlus will allow at least 30W of power and potentially up to 45W.
Phihong has already developed many products that deliver high-power PoE, but most customers would prefer a common industry standard for all devices on the market.
Applications that will benefit from the IEEE802.3at initiative include wireless multi-radio access points, pan tilt zoom security cameras, and IP phones with streaming video displays.
"For some interested in implementing PoE, 12.9W maximum of 'af' just isn't enough power", said Hopwood.
"PoEPlus will allow increased power to many more devices, enhancing their capabilities, such as those used for streaming video, VoIP, IP security applications and broadband wireless access points".
Other emerging applications, including emergency lighting, security system sensors and even medical monitoring, will greatly benefit from combining data and centralised backup power.
The IEEE802.3at working group has formed three ad hoc groups to define voltage limits, advanced classification and a MIB (Management Interface Base).
Phihong will be participating in each of these groups in an effort to develop a pragmatic standard and ensure Phihong products comply to the standard as soon as it is released.
The next meeting will be held in Denver in March.
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