The Current War Rematch at the Edge – My VantagePoint

Eric Broockman Chief Technology Officer Published 9 Dec 2019

Edison vs. Westinghouse Round Two

There is an interesting movie out about The Current War – the collision between George Westinghouse and Thomas Edison over the type of electrical power for both home lighting and ultimately appliances. Edison pushed DC current and Westinghouse (with some genius from Nicola Tesla) fought for AC. So, we know who won the war of course – or do we? 

A century later as we all watch this interesting movie on the current war between these two giantsin the guts of the shopping mall at our local Cineplex, there is a new and silent current war being won by the ghost of Edison. DC current is chipping away at AC when it comes to our day-to-day lives, and moreover, DC is taking share as we look into the future.  So – what is that all about? We are all familiar with the fact that in our everyday lives, we are continuously hunting for DC power – in the form of a phone charging cable, or a USB-C connector for our laptop. The backend of this adapter is an AC outlet – but more and more we are finding DC in the form of USB ports in the chairs of planes, our cars, etc. DC is coming to the edge.  

Perhaps much more interesting, in the reversal of fortunes of that earlier war, is the use of new forms of PoE direct current that are 60W and 90W. These levels of power along with its concomitant wiring simplicity open up entirely new forms of the wiring of Smart Buildings when coupled with the introduction of LED light trays powered by PoE. Moreover, in the Smart Retail marketplace, higher power PoE can actually be used to power many forms of checkout stands; thus providing flexibility to the retailer while greatly reducing costs. Pulling a Cat-5 cable is far cheaper than hiring a certified electrician to install AC in a conduit. Furthermore, leveraging sophisticated forms of .1BR port extension technology enables Smart Retail to extend the range of DC PoE Ethernet to 200 meters. 

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But, where is this ultimately going when we look at the Smart Building of the future, or the Smart City of the future, or the Smart Retailer or the Smart Healthcare facility? If we think of a hospitality use case – think of all of the gizmos in a hotel room that could be powered by DC PoE. The smart thermostat, the information touch panel on the wall, the wireless access point, the mini set-top box, all of the LED lighting, etc, etc. In a similar fashion, a checkstand for a retailer can power their hand-held scanner, the weigh scale, the touchpad, a printer and much more. 

Ok – so the ghost of Edison is winning more of the power war for Smart Buildings as PoE takes over a larger and larger percentage of the inbuilding device power. PoE, of course, is no substitute for long-range transmission of power with AC, and not so good for powering your home air conditioner, and . . . but wait a moment. If you have solar panels, you have access to DC power which may be converted to AC in order to operate a traditional air conditioner. This same panel can provide DC into a wall storage battery to power up your electric vehicle or to use as supplemental power at different times of the day. Again, DC is creeping in at home, not just in the Smart Buildings of the future. 

Now let’s think about IoT devices. We are being overwhelmed by smart things of all types. The problem is that classic 4wire Cat-5 PoE Ethernet is just a bit cumbersome, a bit inflexible, and somewhat too expensive for the majority of more telemetryoriented IoT use cases. Have you heard of SPE – Single Pair Ethernet? Though today the prevalent version of this technology is focused on the automotive market, a new proposed variant is targeted at delivering 15W or power over very simple twisted pair, capable of supporting up to 10Mbps. For dozens of IoT use cases, this is more than sufficient for devices that often operate at hundreds of bits/sec, or perhaps kilobits per second. For a smart retail, you can envision refrigerator cases using this to power and connect to sensors of various types. You can easily envision many other sensors for other IoT use cases as well. Just another front on the silent, but friendly do-over of the current war, a sequel played out over 100 years later. This time Edison is winning a piece of the action with the steady march of PoE across more and more edgeoriented applications.

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