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Title WP-37- The Benefits of PoE for Industrial Applications REV0-1909-1/5 © 2009 by B&B Electronics.

The Benefits of PoE For Industrial Applications - 59059 The Benefits of PoE For Industrial Applications

The drive for Power over Ethernet (PoE) started in the late 1990’s. At first, Voice Over IP needed power from a separate source. The simple DC power of Plain Old Telephone Service was missed. PoE answered the question of how to provide power and data over a single cable, simply and dependably Early proprietary solutions for PoE gave way to standards based ones, after IEEE 802.3af was finalized in 2003. The standard provides for 15 watts at the source, at a nominal 48 VDC. Key devices are Power Sourcing Equipment or PSE (usually a PoE enabled switch) at one end and a Powered Device or PD at the other. The reliability and cost effectiveness of providing both data and power over a single cable are improved with PoE. We’re just starting to explore what PoE can do.
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Cost effectiveness make PoE a natural fit for industrial applications. And as the technology matures, it will become the logical choice for many reasons.

A “Missing Feature” Finds A Home In Industry

PoE is an elegant technical solution. As Ethernet-TCP/IP has become common in control rooms and network backbones and access links, PoE will expand the use of Ethernet on the factory floor. There’s now no technical reason why Ethernet can’t reach and power most industrial devices. Here are some of the benefits that motivate the move to PoE in industrial settings. Cost Using one cable for both data and power to industrial devices is most cost effective, for both installation and maintenance. The cost to run a power cable can be $10 to $100 a foot, and changes may be frequent. Safety PoE is a safe power solution. Maximum voltage is under the limit for “high voltage” applications. To avoid damaging devices or accidental contact with even this relatively safe level, the PSE sends a 10 volt test current to verify there’s a 25 ohm resistor at the PD before full power is applied. If the PD stops using power, power from the PSE stops and testing resumes. Over-current, under-current and fault protection are also part of the PoE standard. Flexibility PoE is standards based, so interoperability across vendors is guaranteed. All variations of network topologies can be configured with PoE, including ring, mesh and other networks. Plus, industrial
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