About passive POE, active POE, POE+ & POE++

Power over Ethernet (PoE) is a technology that allows network cables to carry electrical power along with data, enabling powered devices to receive power and data from a single Ethernet cable. PoE is commonly used for powering IP phones, wireless access points, and network cameras, among other devices.

There are different types of PoE, including Passive PoE, Active PoE, PoE+, and PoE++. Here's a brief overview of each type:

1. Passive PoE: In Passive PoE, power is simply applied to the Ethernet cable, regardless of whether a device is connected or not. The power level is fixed and cannot be adjusted. Passive PoE is often used for non-standard applications and can be less reliable than other types of PoE.

2. Active PoE: Active PoE uses negotiation between the device and the power source to determine the required power level. This allows for more precise power delivery and can help prevent damage to devices that cannot handle higher power levels.

3. PoE+: PoE+ (also known as IEEE 802.3at) provides up to 30 watts of power per port, which is more than the 15.4 watts provided by standard PoE. This allows for powering devices that require more power, such as pan-tilt-zoom (PTZ) cameras and video phones.

4. PoE++: PoE++ (also known as IEEE 802.3bt) is the latest PoE standard and provides up to 90 watts of power per port. This is enough to power devices such as high-end IP cameras, video conferencing systems, and industrial equipment.

In summary, while Passive PoE is the simplest and least expensive option, it can be less reliable than Active PoE, which offers better power management and device protection. PoE+ and PoE++ provide higher power levels and are suitable for more demanding applications, but require a PoE+ or PoE++ compatible switch or injector.