PoE (Power over Ethernet) provides an extremely convenient way of supplying power to large numbers of Ethernet-enabled devices. By supplying power over the same twisted pair cable used to transmit data, PoE has changed the very nature of the network infrastructure of a variety of industrial applications, as it has considerably reduced the effort required to install power cables, and has allowed more communication units to be connected to the same system.
PoE Plus has brought industrial development into a completely new era, since devices that require high power can now be easily connected to and implemented as part of an Ethernet network, thereby expanding the scale of the network and adding more benefits. However, ideal industrial PoE Plus Ethernet solutions require a sophisticated design, and should have the right set of characteristics to be suitable as reliable power supply units that can connect powered devices like IP cameras, network routers, and control units.
The Right Set of Requirements
An ideal industrial PoE Plus Ethernet switch must satisfy several requirements:
To be suitable for use with heavy-duty industrial powered devices, the switch must be able to supply a high power output that meets or exceeds the level required by the PoE Plus standard.
The switch must support Gigabit Ethernet, since many heavy-duty industrial powered devices are expected to transmit over a wide bandwidth.
The switch should support a smart management tool that makes it easier for human operators to control and monitor powered devices.
The switch needs to be industrial grade to provide the level of reliability required to operate successfully in harsh environments.
1: High Power Output for High-Power Devices
PoE Plus is based on the IEEE 802.3at standard, which requires PoE Plus switches to supply up to 30 W of power. This is almost twice the level required by the IEEE 802.3af standard, which requires a maximum power supply of 15.4 W. The IEEE 802.3at standard was created to accommodate the increasing number of industrial applications that are using heavy-duty powered devices, including PTZ/outdoor cameras, LED display boards, and long distance LAN devices, which are showing up in more and more industrial applications. The characteristics and requirements of each of these high-power devices are outlined below:
Low-power IP cameras are well-served by IEEE 802.3af PoE technology. However, cameras that support PTZ (Pan/Tilt/Zoom) functionality, which require more power to operate their PTZ motors, have become increasingly popular. PTZ cameras are often used as part of safety-critical applications, since fewer cameras are required to give security guards complete visibility of their entire perimeter, and cameras designed for harsh, outdoor conditions need more power to run their heater and/or wiper units. 802.3af PoE technology simply isn’t capable of providing enough power for these devices.
LED Display Boards：
Ethernet-connected LED display boards that display up-to-date messages transmitted over a network are being used in a wide range of industrial applications, including intelligent transportation systems and railway onboard systems. The displays use bright LEDs, which demand substantially more power than the 15.4 W available from an IEEE 802.3af PoE line.
Long-Distance LAN Devices：
Basic wireless access points can accept 15.4 W of power. However, high-performance wireless devices that provide wider coverage use high-gain antennas and multiple RFs, all of which demand much more power. These high-power wireless devices are particularly common in widely distributed, remote applications, which are precisely the type of applications for which power supplies and cables are a major cost. However, power supplied by IEEE 802.3af devices is too weak to offer a viable alternative to conventional power sources.
An important point to keep in mind is that when high-power devices are turned on, the inrush current that’s generated might exceed 30 W, albeit for a brief 1 to 2 millisecond time interval. However, as the current rushes in, the PoE port will interpret the rush to mean that the device requires more power than it actually does, and then disconnect its PoE function. The best way to avoid this situation is to offer a power supply higher than the maximum wattage required by the PoE Plus standard.
2: Gigabit Ethernet for Bandwidth-Hungry Systems
In addition to being required to generate a high power output for high-power devices, PoE+ switches are also required to support Gigabit Ethernet to provide enough bandwidth for seamless network transmissions. As we saw in the previous section of this article, devices like PTZ cameras, LED display boards, and high performance wireless devices that can generate large amounts of data need sufficient bandwidth to ensure smooth communications. For example, PTZ cameras deployed to provide greater visibility are likely to support HD imaging, which requires a large bandwidth to provide seamless video streaming. A similar situation also applies to LED display boards used to transmit multimedia information that includes data, voice, and video, which needs Gigabit bandwidth to support continuous information delivery.
3: A Smart Management Tool for Specific Industrial Tasks
PoE+ communication requires a smart tool that can handle specific industrial tasks, such as power management, power scheduling, PD failure detection, and a remote PD reboot function. The tool must be multi-functional and easy to handle from the control room. A web-based console design is ideal, since it allows system managers to easily monitor and diagnose the power mode of the PoE Plus switches. In addition, the tool should be capable of troubleshooting single failure points by checking the indicator status of an LED.
4: Industrial-Grade Reliability for Harsh Environments
Since PoE Plus switches are often implemented at field sites where the environment could be extremely cold or hot, unusually wet or dry, or hardly accessible, reliability is a critical factor for guaranteeing reliable system operation. The switches must be able to endure a wide range of temperature changes, from -40 to 75°C for example, so that they will be able to work reliably in extremely hot or cold conditions. In addition, to guarantee that they will continue to operate when hit by a sudden power surge when transmitting data, they must satisfy strict LAN surge protection requirements to survive voltage surges as high as 3 kV.
Moxa’s Solutions Satisfy High Power Requirements for Industrial Applications
There is an ever-increasing demand for PoE Plus Ethernet solutions that can offer a higher power capability, bigger network bandwidth, a smarter tool that makes it easy to monitor and manage remote PD units, and greater reliability to ensure stable and continuous network communication.
Moxa’s EDS-G512E-8PoE switch is a powerful data communications solution that supports up to 8 Gigabit Ethernet PoE+ ports and is perfect for high bandwidth, high power device communications, including IEEE 802.11n and IEEE 802.1ac wireless access points and high resolution GigE machine vision cameras. The EDS-G512E-8PoE can provide up to 30 W of power per PoE+ port in standard mode, and allow a high power output of up to 36 W to handle the inrush current generated when heavy-duty industrial powered devices are turned on. Moreover, the smart management tools supported by the switch include power management, PoE diagnostics, and LED indicators for easy troubleshooting, allowing operators to manage the status of their powered devices. Industrial reliability features include wide temperature support, 3 kV LAN surge protection, and a redundant design to ensure network availability. The complete package of high power, high bandwidth, easy management, and industrial reliability make the EDS-G512E-8PoE series the ideal industrial PoE Plus Ethernet solution for any industrial application.