PROVIDING MAXIMUM POWER FOR POWER OVER ETHERNET OVER OPERATING TEMPERATURE RANGE
Publication Date: 2010-Aug-09
The IP.com Prior Art Database
Roni Blaut: INVENTOR [+3]
A fixed minimum power, which is valid over the entire temperature range is defined. Power in excess of this limit is allowed by allowing power draw up to the temperature dependent allowed power. Optionally, for power draw up to the temperature dependent allowed power an alarm condition is set.
PROVIDING MAXIMUM POWER FOR POWER OVER ETHERNET OVER OPERATING
Power over Ethernet (PoE) supplies power from a power sourcing equipment (PSE) to a powered device (PD) over structured communication cabling, typically in accordance with IEEE 802.3af or IEEE 802.3at. Upon discovery of a connected PD requesting power, a PSE is to supply the requested PSE, provided that the PSE has sufficient available power.
A PSE unit, such as a switch or a midspan, arranged with a plurality of ports, is typically supplied with a single power source. Often, the single power source is insufficient to supply the full allowed power for each of the ports of the PSE unit or midspan. This is particularly true when taking into account the temperature derating of the single power source.
In further detail, the power source is rated to provide a maximum rated power whose value changes responsive to the ambient air temperature. As the ambient air temperature rises towards a maximum rating the maximum rated power of the power source declines.
In order to reliably provide power over the operating temperature range, prior art devices de-rate the power supply in accordance with the maximum temperature. Thus, the prior art sets a fixed limit for available power which is lower than the actual available power at most ambient temperature conditions.
Description of Preferred Embodiments
The PSE unit is supplied with ambient temperature information, either by supplying an on-board temperature sensor or by receiving over the network ambient temperature information.
In a first embodiment, the available power limit is set responsive to the received temperature information. In this first embodiment, the PSE unit supplies power up to the temperature dependent available power limit (TDAPL), or up to a guard band set in relation to the TDAPL, as described in U.S. Patent 7,257,724 issued 14 August 2007, and in U.S. Patent Application Publication S/...