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I noticed, that there is no clear notification about PoE voltage. For example, I bought TP-Link WA901ND WiFi AP, which is entitled as supporting PoE. There is no clear statement, on which voltage this PoE should be. Simultaneously, this AP is packaged with 12V adapter and PoE adapter, which allows to feed power into the wire.
It works, but what will happen, if I plug this AP into switch also supportin PoE like D-Link DGS-1008P? There is also no clear statement, which voltage it passes to the line.
In wikipedia I see it can be more than 40V!
What will happen if I plug WA901ND into DGS-1008P? It will just burn?
How to avoid this?
Or PoE can adapt voltage automatically somehow?
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PoE is typically 48v, and it is a "negotiated" service. When a PoE device connects to a switch, it does handshaking with the switch on it's initial connection to start the PoE power. In normal PoE equipment there is no danger in connecting a non-PoE device to any PoE port. Wikipedia has a some nice info on how PoE works https://en.wikipedia.org/wiki/Power_over_Ethernet Basically, if your device supports standard PoE, it will tell the injector/switch what power it needs and the switch/injector will provide it to the device. There is no danger to your device.
– acejavelin – 2016-07-27T11:23:23.560