The Power over Ethernet (PoE) uses a single Ethernet cable to transmit both power and data to the edge device. It eliminates the extra power cord to the edge device. Where the cable go, the power arrives. It not only simplifies the cable wiring but also saves the installation time and cost.
I guess we are all familiar with the network. The mobile phone, tablet, PC computer require the network to access the information online. The WiFi, 3G/4G even 5G become popular ways to access the internet. However, in the commercial infrastructure, we still use the Ethernet cable (cat5e/cat6) to link the IP devices to a switch. The typical application is the connection between the IP camera and the Network Switch. The Wireless is not reliable, especially where there are mass devices that are being deployed in the field. The cable is still a reasonable solution.
The Ethernet cable (cat5e/cat6) is conduct which not only can transmit the data, but also the power. Power over Ethernet cable comes from that. After all, the IP edge devices such as IP camera, assess point, VoIP also needs power. What a good idea to satisfy two requirements with a single Ethernet cable.
The PoE Power traveling through the cable is DC power which is safe for humans. Unlike the AC power may do serious harm to humans. The PoE Power is limited to DC57V, but usually, we use a voltage between DC48V-DC55V. In the PoE Power system, there is always a power supply unit that converts the AC power to DC power.
What are PSE and PD?
The equipment which supplies the power is PSE. The PoE Switch, PoE injector, and PoE NVR belong to PSE. The PoE injector is simply the power source to inject the power to the Ethernet cable. The PoE injector doesn’t provide data exchange. The PoE injector has to attach to a regular switch to obtain the data. After the injector combine both data and power, it will then send to the remote edge devices. The PoE Switch has integrated a regular switch and POE injector into a single device. The POE switch provides not only data but also power. You can connect the PoE IP device to PoE Switch, the edge device will have both power and data.
PoE NVR is the network video recorder with PoE Switch integrated. It is a cost-effective solution to install the IP surveillance system. Only all the connection has returned to the PoE NVR.
The edge device which features PoE is PD (powered device). The PoE IP camera, PoE access point, PoE VoIP belong to PD. The PoE Power system uses DC48V-DC55V power and most of the low voltage devices use DC12V-DC5V. The first thing the PD needs to do is regulate the voltage to DC12V. There should have a circuit design to regulate the power in a PoE edge device.
The second thing the PD needs to perform is the power handshake. In the IEEE802.3 standard, the PSE (PoE Switch or PoE injector) should perform the power handshake before PSE can send the power and travel through the Ethernet cable. Technically, the PSE sends a small current to the edge device, and the PD (IP camera, access point, VoIP) should return the feedback current, so the PSE can verify whether the edge device is POE compatible or not. The PD needs an extra Circuit design to complete the Power handshake, otherwise, the PoE system will not works.
If your edge device doesn’t feature the PoE function to regulate the power and perform the power handshake, you can add a PoE splitter before the edge device. The POE splitter can receive the PoE and separate the power from the data, as well as regulate the power output.
Can I use connect the no-PoE device to the POE switch?
PoE Power handshake has answered one question. Can the PoE Switch work with non-PoE edge devices such as PC computers? The answer is yes. While the PoE Switch detects the edge device doesn’t feature with POE, the switch only supplies data that works exactly the same as the regular switch. However, there is one kindly non-standard POE, also call Passive PoE. The Passive PoE has removed the PoE Power handshake and release power after the edge device is attached to the switch. Just be careful to use Passive PoE unless you know what you are dealing with.
Expand PoE beyond 100 meters
The PoE is limited to 100 meters according to the IEEE802.3 standard. In some practical installation, you may need PoE beyond 100 meters. Can we just add extra cable to reach 200 meters PoE? The answer is negative. What could go wrong after 100 meters?
The first thing is the data. You may have no data after 100 meters. The power handshake could be another problem. Everything means to be within 100 meters. If the power handshake can’t be done, the PoE Switch will never release the power at all. The power seems to be the easier part because we can’t boost up the power after all, but once the power loss inline is being considered, we need to deal with power as well. Power loss is a very tricky thing in long-distance PoE.
The below are the solution which can extend the PoE beyond 100 meters. We will see how each one deals with the power and data.
1. PoE Switch and CCTV mode
Some of the PoE Switch support CCTV mode. With CCTV mode enabled, the switch can supply 250 meters of PoE. Why it name CCTV mode? because this feature design only for IP cameras. It trades off the bandwidth and the distance. While CCTV mode is turned on, the bandwidth will reduce to 10mbps. It still can carry one 1080p IP camera. However, if the resolution goes up, the bandwidth will become block neck. The IP camera should return to an NVR. Otherwise, it may still create new issues while multiple users trying to access the camera at the same time. The bandwidth will double when two video streams going out from the same IP camera.
Moreover, the CCTV mode has to compromise all the PoE ports. You can’t just enable the CCTV mode for specific ports. That is why VLAN has to be turned on automatically while the CCTV mode is enabled to make sure each of the ports doesn’t occupy the bandwidth from each other. Never use the CCTV mode to connect the NVR. The NVR needs to connect to all the IP cameras which need higher bandwidth rather than a single IP camera.
2. PoE Extender
The PoE extender is the most common solution to repeat the PoE Network. You only need the PoE extender for the ports you want to extend the PoE Network. The PoE extender doesn’t require an external power supply unit. The extender can take a small part of the power from the back-end PoE Switch and forward the reset of the power to the edge PoE device. Basically, the PoE extender doesn’t process the power, but it still provides the power handshake. If the edge device is not standard PoE, the PoE extender will not release the power at all. The whole PoE system still should satisfy the IEEE802.3 PoE specification.
Rather than a power handshake, the PoE extender can boost up the data. You can daisy chain the second PoE extender to the link to achieve 300 meters POE link. The power loss also needs to be considered. Technically, we can’t boost up the power. Since the distance increase, more power loss will happen inline. It is important to evaluate the power consumption of the edge device.
3. Ultra Distance Distance PoE extender
Technically, we can chain up to 4 units of PoE extender to achieve the 500 meters distance. However, we don’t recommend keeping more than 3 nodes (PoE extender) between the edge device and the back-end equipment, especially for the IP camera system. Too many nodes between the edge device and the server could cause the delay, even the frame dropping. The fast cabling Ultra long distance PoE extender has equipped with a special chipset to achieve 300 meters between two PoE extenders. Plus the 100 meters to the back-end and another 100 meters to the edge. One pair ultra long-distance PoE extender can achieve 500 meters PoE.
Now we can explore the exploit 300 meters for burial solution. No matter how reliable the PoE extender, it still the activated devices. As there are 300 meters between two PoE extenders which is pure cable. If there are less than 300 meters between the edge device and the server, we can install two PoE extenders at both ends, and leave simply the cable between. The cable is the most reliable solution to bury. One thing to point out, the edge device has to be standard PoE with IEEE802.3 compatibility. The ultra long-distance PoE extender doesn’t provide the power handshake. The power handshake needs to be done between the PoE Switch and the PoE edge device. If your edge device is non-PoE equipment, this solution will not work. You should add a POE splitter at the end to complete the power handshake.
4. PoE Powered Switch
The PoE extender can repeat the specific PoE distance. Sometimes, we need expand PoE ports at the edge as well. The most logic solution is wiring extra power cable from the PoE Switch to the edge. It is just not so easy to wire the new cable which could cause the break down in the business. The POE powered switch is the perfect solution. The POE powered switch can receive the power from back-end switch and provide the multiple standard PoE output at the edge. The maximum distance between the edge device and the back-end switch is 200 meters.
The powered power switch work very similar to POE extender, only the PoE powered switch provide multiple PoE output. It may doesn’t make sense to use PoE powered switch with POE+. The maximum power budget of POE+ is 25.5W. Thanks to new PoE standard IEEE802.3bt (aka PoE++). The power budget has increase to 72W. There is about 70W remaining power at the POE powered switch to supply the edge devices. Now you still can hook up 5-6 IP cameras after 100 meters. The PoE powered switch not only expand the distance but also the PoE ports.
5. 800M PoE Switch
The 800 meters PoE Switch is designed for ultra long distance POE. Even the standard cate5/cat6 cable is 300 meters in roll. It will need about 3 roll cable to come up with 800 meters by using the ethernet coupler. There is no need for any activate device within 800 meters, but it do needs PoE adapter sitting next to the edge device. The PoE Switch is capable of sending 800 meters, but you will need PoE adapter to return the single, that is what the PoE adapter do.
The bandwidth is 100mbps within 500 meters with 22W power budget. All 4 twisted pairs has been used to transport the power. The bandwidth will reduce to 10mbps after 500 meters which is still enough for one IP camera. The beautiful thing is you can use 500 meters pure cable to come up with 100mbps PoE Network link with 22W power.
6. Fiber Optical PoE Solution
The fiber optical cable is plastic. Technically, the power can’t travel through the fiber optical cable, but we still can exploit the feature of fiber optical cable. One of the advantages of fiber optical cable is long distance. It is very easy to set up a 10-kilometer fiber optical network with a common single-mode fiber optical cable. We should have fiber optical converters on both ends to convert the signal to electricity (RJ45). The PoE feature can be added to the edge equipment. The PoE Switch with a fiber optical slot could serve the purpose. The PoE Switch will receive the data several kilometers far from the center. The PoE Power can be taken from the local power source at the edge. All the above solutions still can be used to extend the POE. Now just there is several kilometers network link being added to the system.
The PoE solution is the centralized power solution. All the power could come from the same switch. Now backup the whole power system becomes possible and easy.
