Poe plus enabling ip convergance over twisted pair cabling
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PoE Plus Enabling IP convergance over twisted pair cabling. PoE Plus. Definition Standards Advantages/Drawbacks Modelling Cabling Options Benefits of higher graded Cabling. PoE : what is it?.

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PoE Plus Enabling IP convergance over twisted pair cabling

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Poe plus enabling ip convergance over twisted pair cabling

PoE PlusEnabling IP convergance over twisted pair cabling

Poe plus

PoE Plus

  • Definition

  • Standards

  • Advantages/Drawbacks

  • Modelling

  • Cabling Options

  • Benefits of higher graded Cabling

Poe what is it

PoE : what is it?

  • Power over Ethernet describes any system to transmit electrical power along with data over standard twisted-pair cable in an Ethernet network.

  • The IEEE802.3af standard provides the capability to deliver both power (max 12.95W) and data over standard ethernet Cat.3/Cat.5 cabling.

Working principle

Working principle

Usb firewire poe


Actual applications

Actual applications

  • Power supply <13W

    • IP phone

    • Webcam

    • Wifi Accesspoint

Future applications

Future applications?

  • Charge of a laptop

  • Providing both power supply and internet connection in trains and planes

  • Peripheral devices : screen, printer, home theatre…

  • Power backup for PC

  • Power supply for specific PC

Examples of power consumption

Examples of power consumption



  • Advantages :

    • Only one cable to carry datas and power

    • Up to 100m

    • Ethernet connector standard (RJ45) is widespread

    • Compatible with Gigabit Ethernet (1000BASE-T)

    • centralized backup power

Challenges and answers

Challenges and Answers

  • Learnfrom the challenges at the beginning and how they have been answered

    • Data cables are not made for this use (copperconductors are toothin,

      • 24 AWG = diameter of 0.5106 mm)

    • Higher power levels over thincoppercableslead to temperaturerise in cables

      • What are the limits ?

      • Do weneed new cables?

Nexans thermal modell

Nexans Thermal Modell

  • 3D Modelling Project in Nexans Research Center, France

Nexans modelling results 1

Nexans Modelling Results (1)

  • Heating of Ethernet cable depending on the category

Nexans modelling results 2

Nexans Modelling Results (2)

  • Heating of a bundle of cat5e ethernet cables

Nexans modelling results 3

Nexans Modelling Results (3)

  • Power of 1A results in ~10° temperature rise in a bundle of 19 cables

Results for cat5e utp cable worst case

Results for Cat5e UTP cable (Worst Case)

  • Cat5e UTP usable if bundle size <100

Isc sc25 poe ad hoc result

ISC SC25 / POE Ad Hoc Result

  • ISO SC25 Temp. Rise Data provided to IEEE

    • For 100 cable bundles Cat5 UTP minimum: all pairs energised

Ieee choice

IEEE Choice

  • Maximum acceptable Temperature Rise = 10°

    • Max maximum rating for cable = 60°

    • Max temp for equipment / ambient temperature = 45 ° = 15° Max.

    • Including some tolerance finally 10° Temperature Rise accepted

  • Leads to limitation to 25 Watts

    • 10° TR equals 600 mA

    • using 57 Volts  24/25 Watts Limitation (using 2-pairs only)

  • 50 Watts target only achievable with 4 pairs but this is patented technology

    • No licenses available (PowerDesign)

  • Ieee standards

    IEEE Standards

    • The existing standard : IEEE802.3af (PoE)

      • 48V DC over two pairs of cat3/cat5 ethernet cable

      • 400mA per pair

      • 12.95W (with losses)

    • The future standard : IEEE 802.3at (PoE Plus)

      • Uses the up to four pairs of cat5e cable

      • 57V DC

      • 600mA per pair

      • Up to 25.5W



    • FINALLY:

      • POE PLUS is possible with ALL Copper LAN Cables !!

        • IEEE Standard based on worst case CAT5e UTP

        • No need for ‚thick‘ cables

    • Big Achievement:

      • Run POE PLUS and IP Convergance over existing LAN cabling

    • ..but some cabling can support it better than others.....

      • Get around some limitations and compromises made to enable worst case

    Benefits of better cable

    Benefits of better cable

    • Let us look into benefits of better cabling. This would potentially allow

      • Limit the temperature rise (and save energy for cooling(?))

      • Tolerate higher power levels (some equipment oversubscribes)

      • To use larger bundles than 100 cables or even “bundles of bundles”

      • Tolerate environments at higher temperature without reaching the 60° limit when using PoE+

      • Keep maximum distances (100m)

    Poe p 2 pairs

    POE /P 2 pairs

    Temperature Rise per cable grade remember to double temperature rise due to 4 pairs (IEEE) instead of 2 pair (used in comparison these chart) Almost linear behaviour from 2-4 pair!!!

    Temp rise per cable grade

    Temp Rise per Cable Grade

    Difference between AWG 23 and AWG 22 cables is 1° !!

    Acceptable ambient temperature

    Acceptable Ambient Temperature

    Tolerate higher power levels

    Tolerate higher power levels

    Cat7A cable would allow to run ~ double power level

    Larger bundle size

    Larger Bundle Size

    AWG 23

    10 bundels = 331 cables

    AWG 22

    10 bundels = 331 cables

    Impact on distance

    Impact on distance

    • All International Standards specify insertion loss requirements at 20° C and have quantified a small increase of attenuation of less than 0.2%/degree C for shielded cable and up to 0.6%/degree C for unshielded cable.

    • UTP Insertion Loss

      • Reduces by -0.6%/degree C

      • Example: +10° for UTP

        • 90m - 6% = 84,6 m link length

      • Example: 60° for UTP

        • 90m - 24% = 68,4 m link length

    • FTP Insertion Loss

      • Reduces by -0.2%/degree C

      • Example: +10° for FTP

        • 90m - 2% = 88,2m link length

      • Example: 60° for FTP

        • 90m - 8% = 82,8 m link length

    In High Temp envronments use higher cable grade to ensure 100m distance (application dependend f.ex. Cat5 app over Cat6 cabling)

    Impact for office cabling

    Impact for Office Cabling

    • High Impact estimated for Office Cabling where a frequent use of POE/P can be expected

      • Devices like VoIP Telephones, Sensors, Printers, thin clients, new generation laptops require pontially fully energised large bundles of cabling

  • Bundles Size in horizontal cabling = typically 100 FD, often larger than 100 cables

    • 1 Floor of 50 users equals 150 cables at 3 drops /users

  • Summary


    • POE/P is a key technology to enable IP Convergence

    • Cat5e UTP cabling is required as a minimum

      • 10° temperature rise at 600mA per pair

      • Max. bundle size = 100

    • Better cabling Higher Grade (Cat 6 and Cat7) or shielded cable allows to

      • Lowering the expected temperture rise

      • Use larger bundles sizes

      • Tolerate higher power level

      • Save energy for cooling in comms rooms

      • Enable full distance of 100m

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