PoE+
How it works
The power source (PSE — Power Sourcing Equipment, e.g. a switch or injector) and the Powered Device (PD) negotiate a power class via a resistive signature or the LLDP protocol. The PSE supplies 50–57 V DC, the PD operates at 42.5–57 V, with current up to 600 mA per pair. Power and data travel over the same standard Category 5 (or better) Ethernet cabling (up to 100 m). 802.3at uses two wire pairs and does not allow powering over all four pairs simultaneously.
Problem solved
Plain PoE (802.3af) delivered only 12.95 W at the device, which was not enough for more power-hungry edge devices such as PTZ cameras, access points or vision modules. Powering such devices separately meant running mains power and a socket to every mounting point, raising cost and complicating installation.
Evolution
The first PoE standard — up to 15.4 W at the port, 12.95 W guaranteed at the device.
The update raising power to ~25.5 W at the device; introduces power negotiation via LLDP.
Four-pair power — up to 51 W (Type 3) and 71.3 W (Type 4) at the device, up to 90 W at the port.
The PoE standards were merged into the main IEEE 802.3 revision.
Hyperparameters (configurable axes)
Power delivered by the standard.
DC voltage range.
Maximum current per wire pair.
Cabling requirements.