Control Network Newsletter
Understanding Power over Ethernet Options
We often have customers who need a solution when they are installing an access card reader or a security camera on their Ethernet network at a remote spot with no immediate source of power. When both battery and solar power are not feasible, Power over Ethernet (PoE) is often the most economical solution.
PoE equipment adds power along with data to Ethernet wiring so devices, such as surveillance and card access machines, can be powered via standard Ethernet cabling. Power Sourcing Equipment (PSE), such as the Skorpion PoE Injector and Skorpion PoE Gigabit Switch, provide the required 48 VDC power onto the Ethernet cable while the Skorpion PoE Splitter extracts power from the Ethernet cable to power non-PoE compliant Powered Devices (PD). All PoE models support the IEEE 802.3af standard.
To better understand PoE, be sure to review Information Sheet—The ABCs of Power Over Ethernet (PDF).
PoE Mid-Span Injector
PoE requires a 48 VDC power source but most automation systems operate from 24 VAC/VDC power. If only one PoE device needs to be powered, an injector like the EIPE-1 can be used. An injector is inserted mid-span between a standard Ethernet switch and Ethernet powered device (PD). Power to the injector can be either 24 VAC or VDC. The injector develops the required 48 VDC and injects the voltage into the Ethernet cable in order to provide power and data to the powered device.
PoE Mid-Span Splitter
Under certain circumstances, a non-PoE compliant device can be made compliant with the use of the EIPE-2 splitter. If the end device is 10/100 Mbps Ethernet-based but requires 24 VDC to operate, the splitter will accept combined power and data connections from a PoE-compliant power sourcing equipment (PSE) and use the 48 VDC to generate 24 VDC at 10 W to power the end device while passing the data signals.
End-Point Power Sourcing Equipment
For multiple PoE port applications, an Ethernet switch equipped with PoE sourcing ports is required. An end-point PSE, such as the EISK8P-GT, can drive a PoE splitter or a PoE compliant powered device directly. Power for the PoE switch is derived from an isolated 48 VDC power supply. PoE applications typically involve surveillance and card access systems.
