Power Over Ethernet Interoperability Guide

Maximum Power Delivery over Long Distances Using Available PSEs

Here we are restricting ourselves to available PSEs. So we have two types available basically: AF PSEs that can support 0.35 A, and AT PSEs that can support 0.6 A. We will drive this current either through single pair or two pairs. Note that by fixing the port current, the current per strand is perhaps no longer completely “safe” for the single-pair case, because ideally we would halve the port current for that as we did in Fig. 13.2. But we keep in mind that since single-pair cables are not necessarily found in bundles similar to Ethernet cabling, this current level may very well be acceptable in terms of its temperature rise. Let us assume for now, that it is acceptable.

Having ...