Loss of PoE Connection After Transfer to Generator

[ekrengel_apc]

This was originally posted on APC forums on 2/15/2010

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We have VoIP phones that loose connection after we simulate a transfer to our generator. Nothing else looses power of course...but for the however many milliseconds that it takes to transfer to the generator, PoE is lost.

Is it normal for PoE to loose connection after transferring from load on battery, to a generator? If it's not, what is causing this and how do I prevent it?

[BillP]

This reply was originally posted by Angela on APC forums on 2/15/2010

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yes i agree it doesnt make sense because as far as i know, that UPS has a 0ms transfer time.

[BillP]

This reply was originally posted by Laurie on APC forums on 2/15/2010

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I'm not sure I understand the issue. Do you have a UPS in place now? If so, which model? Depending on the unit, I would expect that if your equipment is connected to the UPS and it transfers to battery fine, it would transfer off of battery (online) fine as well. The equipment wouldn't notice a generator, the UPS would, and then the UPS would go online.

Could you offer some more information about your config?

[ekrengel_apc]

This was originally posted on APC forums on 2/15/2010

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Yes we have a UPS in place now (Symmetra 40K and 80k).

I actually think this might be more related to our phone system, Shortel. I just doesn't really make sense because we don't loose power to anything else, but the phones loose connection for a second and reboot.

[upsguy_apc]

This was originally posted on APC forums on 2/17/2010

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The phones or POE injectors are probably not plugged into UPS protected outlets so when the generator comes on they loose power during the transfer. I would have someone verify that the outlets they are plugged into are actually UPS outlets.

Message was edited by: upsguy

[ekrengel_apc]

This was originally posted on APC forums on 2/16/2010

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It's most likely when it transfers off battery, to the generator. The generator has like 33ms transfer time.

[BillP]

This reply was originally posted by Angela on APC forums on 2/16/2010

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ah ok

[ekrengel_apc · Accepted solution]

This was originally posted on APC forums on 2/17/2010

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The Cisco switches, which are UPS protected, provide PoE to the phones (or at least I think). We will have to verify that early morning within the next couple weeks.

It is very possible that those outlets are not UPS protected (even though they are labeled that they are). Our HVAC units shut off for a couple seconds when we transfer over to generator, and could be the same for those other outlets connected to the cisco switches.

Message was edited by: ekrengel