What is the maximum PoE power per port under 802.3af?

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What is the maximum PoE power per port under 802.3af?

In 802.3af, the limit is defined by what the Power Sourcing Equipment can push onto the cable per port. The PSE can provide up to 15.4 watts per port. The powered device doesn’t absorb all of that because some power is lost as heat due to the resistance of the cable and the PD’s own circuitry. As a result, the device typically receives around 12.95 watts at most, with the rest dissipated along the line. So the maximum per-port PoE power from the source is 15.4 W, and the actual PD power is lower because of losses.

In 802.3af, the limit is defined by what the Power Sourcing Equipment can push onto the cable per port. The PSE can provide up to 15.4 watts per port. The powered device doesn’t absorb all of that because some power is lost as heat due to the resistance of the cable and the PD’s own circuitry. As a result, the device typically receives around 12.95 watts at most, with the rest dissipated along the line. So the maximum per-port PoE power from the source is 15.4 W, and the actual PD power is lower because of losses.

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