OJ, Isolation and Bad Decisions
OJ is apparently a slower learner than I have given him credit for. Comprehending how that man’s mind works is well beyond me.
But you, my dear reader, are much easier to grasp. Not because you’re a Simpleton, but because you’re intelligent and pragmatic. When armed with the appropriate information, you make the most correct decision.
As Mark, our esteemed Sales Manager says, “I’ve never made a decision that didn’t sound like a good idea at the time.”
I’m 100% confident that applies to you too. But the treacherous loophole remains. On occasion we all make decisions without the appropriate information.
That's how a good day goes bad.
Quite frankly, I’m writing today’s email because I’ve just caught a couple of you making bad decisions. And since I know you would never make a bad decision if you had all the facts, I blame myself. My job is to give you the right information. I’m ready to take my lashes, but right now let's focus on putting this topic to rest and making sure that you understand the when, why, and what-for of data line isolation.
Here’s the scoop. The crux of all the confusion around the topic of isolation starts with a misguided assumption that electrical “ground” equals zero Volts. Simply not true. While the *average* voltage may well be zero Volts, vast swarms of electronics-zapping electrons are swimming around between your “ground” connections, wreaking havoc in their path.
Throw out the assumption that the two ends of your data cable are both at zero Volts and you grasp the problem. Connecting a ground cable between two ends of a system is, at times, the equivalent of shorting a nearly infinite capacity power supply through your little 22AWG cable and whatever piece of hapless equipment lies at its ends.
Now, if you’ve done your homework (and I’ve done my job) you’ve connected at least one end of that cable to a piece of B&B Electronics equipment featuring isolation. In that case, all those rushing little electrons have nowhere to go. As a result, the voltage at the remote end of the cable will rise to a similar level as the opposite end, but your data will continue to flow without interruption. No smoke, no equipment down, no last minute field visits, no calls to tech support.
To do the job right, you’re looking for Triple Isolation. That simply means that we’ve got three ground connections in any one box to deal with – the field, local and the power supply. Triple isolation, found in our Ilinx line of serial converters and isolators, is the defense you need.
http://www.bb-elec.com/product_multi_family.asp?MultiFamilyId=59&s=INBE0907
But what if the voltage goes too high? Anything up to 2000-3000 volts isn’t generally a problem for our converters and isolators, but if you suspect you’ve got even more pesky electrons lurking, then it’s a good idea to pick a point on your system to install a heavy duty surge suppressor. Its role in life is simply to siphon off some of those rogue electrons to keep things within a range that the isolators can handle. Don’t skimp on that surge suppressor and certainly don’t skimp on the ground connection to it – 12AWG usually isn’t going to cut it, that’s why we make our heavy duty units like the 485HESP so you can bolt them right to your cabinet and teach those electrons a lesson.
http://www.bb-elec.com/product_family.asp?FamilyId=38&s=INBE0907
There you have it, all the information you should need to make the Right Decision. Unlike OJ, I’m confident that you will use it wisely!
Happy Connections,
Mike Fahrion
support@bb-elec.com
(800) 346 - 3119
P.S. I almost forgot. The ISA show is next week in Houston and Yours Truly is going to be there. I'll very likely be chained to our booth (#2259) all week, so stop by to keep me company and I'll show you all the great new stuff that's coming out in October.
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