Introduction to Power over Ethernet
As its name suggests, Power over Ethernet (PoE) is a technology that lets you transmit power and data over a single Ethernet cable. This can be useful in a number of scenarios, such as when you want to deploy devices in locations where there is no easy way to get power to them.
PoE comes in a few different flavors. The most common is 802.3af, which can deliver up to 15 watts of power. There is also 802.3at, which can deliver up to 30 watts of power, and 802.3bt, which can deliver up to 60 watts of power.
In order for PoE to work, you will need both a PoE-enabled device and a PoE injector or switch. The PoE injector simply takes the data and power from your regular Ethernet connection and combines them into one cable that goes to your PoE-enabled device. A PoE switch has built-in PoE capabilities and can provide power to multiple devices at once.
Once you have your hardware set up, all you need to do is connect your device to the network and it will receive both power and data. Pretty simple, right?
Passive PoE
Most of the time, Power over Ethernet (PoE) is used to refer to the 802.3af and 802.3at standards, which are sometimes collectively called Active PoE. However, there is also a less commonly used standard called Passive PoE.
Passive PoE was standardized in 2003 with the 802.3af specification. It allows for up to 12.95 watts of power to be delivered over Ethernet cabling. The main advantage of Passive PoE is that it does not require any special equipment; any Ethernet switch can provide it as long as it supports the 802.3af standard.
The downside of Passive PoE is that it is less efficient than Active PoE and can only be used with shorter cable lengths (up to 100 meters). In addition, due to the higher voltage required, Passive PoE is not compatible with many devices that require Active PoE (such as VoIP phones and Wireless Access Points).
Active PoE
PoE can be used to provide power to devices over an Ethernet connection. This is useful for devices that need to be powered but don’t have a dedicated power source, such as IP cameras or WiFi access points. There are two main types of PoE: active and passive.
Active PoE is the more common type of PoE. It uses a Power Sourcing Equipment (PSE) to inject power onto the Ethernet cable. The PSE has a power supply and circuitry to control the amount of power that is injected onto the cable. The device that is being powered, called the Powered Device (PD), has a receiver that extracts the power from the cable and uses it to operate.
Passive PoE requires no PSE; instead, power is injected onto the Ethernet cable by the PD itself. This type of PoE is less common because it requires special PD hardware that can generate its own power.
High-Power PoE
The PoE standard provides up to 15.4W of power per port, which is enough to power most low-power devices such as VoIP phones and wireless access points. However, there are some devices that require more power than the PoE standard can provide. For these devices, you’ll need a high-power PoE injector or switch.
High-power PoE injectors and switches can provide up to 30W of power per port. This is enough to power high-power devices such as IP cameras and outdoor wireless access points. High-power PoE injectors and switches are also available with multiple ports, so you can power multiple devices from a single unit.
Ultra PoE
There are four types of Power over Ethernet: Ultra PoE, 802.3bt PoE, Passive PoE, and Active PoE. Ultra PoE is the most recent and powerful type of PoE. It can provide up to 100 watts of power to devices, making it ideal for devices that require a lot of power, such as IP cameras and Access Points. Ultra PoE is also backward compatible with older types of PoE.
Conclusion
Power over Ethernet (PoE) is a technology that allows you to transmit both power and data using a single cable. There are different types of PoE, each with its own advantages and disadvantages. In this article, we’ve looked at the five main types of PoE — IEEE 802.3af, IEEE 802.3at, Passive PoE, Active PoE, and High-Power Active PoE — so that you can make an informed decision about which one is right for your needs.
