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Technical article
May 2015 81
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The increasing demand for more power
supplied from the Power PSE to the PD is
obvious, with powering over all four pairs
expected to be IEEE standardised[11] and a
variety of non-standard products currently
available on the market which provide
power levels in excess of those stated in
IEEE 802.3at.
Higher power levels will increase perfor-
mance risk, but will also allow PoE to be
used for a wider range of applications.
Conclusions
A two-dimensional model was set up
using COMSOL Multiphysics software in
order to replicate measured results.
A test method proposed by IEC
subcommittee 46C to assess cables for
Power over Ethernet was followed, which
outlined the measurement for heating
data cables by DC current.
Excellent correlation between simulated
and measured results for a single cable
has been demonstrated. This correlation
encourages use of the software for the
thermal prediction of cables in densely
populated networks. It is also expected
to provide a strong indication of the
temperature rise for varying bundle sizes,
ambient temperatures, and containment
systems, etc.
The thermal performance of a CCA cable
subjected to DC powering has also been
proven to radiate more heat than cables
which use solid copper conductors using
equal DC current values.
Installations using PoE technology differ
greatly in terms of their configuration and
environment.
With an increasing demand for more
power, which is likely to require powering
over all four pairs, further work is required
to investigate cable and component
performance in areas such as bundled
cables, thermal behaviour in different
ambient temperature environments, cable
reach under PoE, and connector demating
under load. n
References
[1] IEEE Standard 802.3at, 2009
[2] M Gilmore, ‘The impact of copper clad aluminium
(and steel) conductors within balanced pair cables
(intended for use within implementations of
generic cabling),’FIA-IAN-002, 2011
[3] IEC Subcommittee 46C, ’Proposal for measuring
of heating of data cables by current,’ 46C/906/NP,
2009
[4] COMSOL Multiphysics:
[5] G J Anders, Rating of Electric Power Cables
in Unfavorable Thermal Environment, Wiley-
Blackwell, pp 2-4 (2004)
[6] National Instruments LabVIEW:
labview
[7] Minitab:
[8] J Wilson and C Hernández-Hall, Physics Laboratory
Experiments, Brooks/Cole, p 361 (2009)
[9] F S Akinnuoye, H Sasse, V Kang, A Duffy, ‘Heating
Effects on channel performance for Power over
Ethernet (PoE) applications,’ Proceedings of the
International Wire & Cable Symposium (IWCS),
November, 2013
[10] H Congdon, B Davis, ‘Mythbusting takes on
shielded cabling,’Bicsi Presentation, 2009
[11] Four-pair PoE study group: 802.
org/3/4PPOE
Paper courtesy of the 63rd IWCS Technical
Symposium, Providence, Rhode Island, USA,
November 2014.