Powering up an EAP245

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Powering up an EAP245

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Powering up an EAP245
Powering up an EAP245
2018-09-03 17:48:14

I have just got some Access Points following an office upgrade.  These are my first POE devices and I am not sure how to power the EAP245.

I have found documentation on the TP Link website that lists the Access Points and the power options for each one and the only option for the EA245 is powering it from a switch.  I have found other documentation that says the EAP245 can be powerted from a passive injector.  Which is right?  I have a 48v 0.5A passive injector but I have heard that passive injectors can damage some AP's so I am unsure.  Any advice would be greatly appreciated....   Thanks.

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#1
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Re:Powering up an EAP245
2018-09-03 19:08:33 - last edited 2018-09-03 19:09:25

Little_Old_Me wrote

I have found documentation on the TP Link website that lists the Access Points and the power options for each one and the only option for the EA245 is powering it from a switch.

 

The documentation from TP-Link for EAP245 describes three possible ways to power an EAP245:

 

  1. Using the 12V power adapter included in the package,
  2. using an IEEE 802.3at (not af!) compatible PoE injector or
  3. using an IEEE 802.3at compatible PoE switch.

 

See the Quick Installation Guide for the EAP245.

 

Don't use a 48V passive power injector, it does not conform to 802.3at.

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#2
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Re:Re:Powering up an EAP245
2018-09-03 19:27:15

Thanks R1D1, I was just about to post that I found out that you could power it off a Passive injector becasue the spec page states:

 

Power Supply

 

802.3af/A PoE
48V Passive PoE (+4,5pins; -7,8pins. PoE Adapter Included)


https://www.tp-link.com/en/products/details/cat-5692_EAP245.html#specifications
 

The TP Link documentation is not clear.  I will have to try to get hold of technical tomorrow.

 

Thanks for the response.

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#3
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Re:Powering up an EAP245
2018-09-03 19:40:52

OK I have sorted it and for the benefit of anyone that comes across this post I will explain.

 

There are actually 2 EAP245 devices made by TP Link, a v1 and a v3 and while they provide the same function they are totally different units.  My v1 cannot be powered by a passive injector but the v3 can be powered by a passive injector.  Why the hell they change the hardware but not the model number is a mystery to me but there you go.  Cheers all.....

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#4
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Re: Powering up an EAP245
2018-09-04 02:38:49 - last edited 2018-09-04 02:48:58

Absolutely right, I also don't like the version numbering for different models such as the EAP225 v1/v2 and v3. Those are completely different platforms with different specs and it would be much better to call them EAP225 and EAP226 or something like this.

 

Note also that EAP245 v1 needs up to 12.7 watts, thus exceeding 802.3af (else you could use 802.3af-capable power injectors such as the TL-POE150S). There are guys using 802.3af power supplies instead of 802.3at (aka PoE+) with the EAP245v1, but maximum power of af injectors is only 12.5 watts over long cable runs. You should always have ~15% reserve in the power budget.

 

Of course, there are indeed 803.3at-capable power injectors on the market, but they are not made by TP-Link.

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#5
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Re:Re: Powering up an EAP245
2018-09-04 16:58:14

Hmmm, I had noted that 802.3af could deliver up to 15.4 W, while only an assured 12.95W due to cable losses....which puts the EAP245 within the range, though a bit close.... but I'm no where close to the 100m limit.  Just a 5m CAT7 ('cause its shielded...)

 

Plus the 802.3af injector I was using claimed to provide up to 19W.  I had missed which I needed, so I got the 802.3af based on these figures....

 

I thought about getting a POE power meter to see just exactly what was being used, etc.  But, buying an 802.3at injector was cheaper...the spec says up to 25.5W, while the injector claims it can do up to 30W.

 

Though I might end up getting a power meter... 

 

LK

 

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#6
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Re: Powering up an EAP245
2018-09-04 18:37:20 - last edited 2018-09-04 18:41:12

TheDreamer wrote

Hmmm, I had noted that 802.3af could deliver up to 15.4 W, while only an assured 12.95W due to cable losses....which puts the EAP245 within the range, though a bit close.... but I'm no where close to the 100m limit.  Just a 5m CAT7 ('cause its shielded...)

 

Depends on the actual voltage (can be 44 to 54V), the length of the cable and the resulting voltage drop. In my experience, a PD can use between 11.5 and 13.5 W, so I calculate with 12.5W (theoretically it's 12.95W on 48V and a loop resistance of 12Ω/100m for the cable, that's correct). Next, actual power requirements depend on the load of the EAP, so with only small loads an EAP245 could easily work with an 802.3af injector, especially on short cable lengths.

 

BTW: CAT.5e cables are available as shielded cable too, even with double shielding (braided shield and foil shield/pair) and also with solid wires, which have better conductivity characteristics for PoE than have stranded wires used in standard patch cables.

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#7
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Re:Powering up an EAP245
2018-09-05 18:25:37

OK I am lost on all the number and haven't had chance to do anything with this AP yet.

It requires 48v at 0.4A and I have a passive POE injector that is rated at 48v at 0.5A.  Clearly this can provide the power needed but will the EAP245 v1 power up or does it NEED to talk to a smart switch?  Oh and the pin out is correct with 4&5 providing the positive and 7&8 the negative.

Thanks...

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#8
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