I have been in the trade for a few years and still learning, so bare with me.. I have heard many different terms in the field, but clean and dirty power are new to me. What does it mean on a commercial job site and what does it refer to? Im thinking ac/dc, transformer, etc.... Im drawing a blank. I know its not solar, wind, etc. Can you tell me what it means?
"dirty" power has a lot of "noise" in it -- surges, sags, sine wave distortions, etc. Many electronic items (including newer ballasts) can't handle dirty power for very long without failure.
See the wave form in my avatar? That is a perfect 60 cycle wave form and perfectly clean power. If it were powering something that was causing distortion or harmonics, you would see it on the oscilloscope as really erratic instead of smooth, that's dirty power.
Some triac dimmers chop off the front half of a wave form, some chop off the back half of a wave form, although not what I would consider "dirty power" it is certainlty not ideal, and can damage fan controllers in ceiling fans.
Im on a job site running seperate conduit runs for "clean power" and "dirty power". Although i dont know what they mean Im pretending to understand... Im at a new company and trying to understand the lingo from my new foreman/co-workers. At this time I dont need to terminate any wires, just continue the EMT runs so, I wont ask what the terms mean.. yet..
Most of the jobs I work we have 'clean' and 'dirty' power.
The dirty will come from any panel with any other type of equipment connected to that panel as well.
The clean may come from just another panel with only similar loads or may the panel maybe supplied by a simple isolation transformer or it may be supplied via a UPS system etc. It all depends on what the engineer is looking for.
Dont pretend to understand something you dont know, this is the wrong trade to act like a smart guy by not asking. Their is two many things that can HURT you. Their is nothing wrong with asking questions it shows you care about your career and want to learn. Dont be that guy that always screws things up on the job because his ego is to big to ask questions.
The terms are relative to the end user, anything that effects your operation. If it doesn't effect your facility there is no issue.
Often (quite often) the power is blamed for anything that goes wrong and the term "dirty power" gets thrown at all issues that in reality are hardware or software problems.
Often (quite often) the power is blamed for anything that goes wrong and the term "dirty power" gets thrown at all issues that in reality are hardware or software problems.
Most likely what they are talking about is "dirty" power is used for receptacles or lighting.
Your "clean" power is an IG circuit, A neutral and a ground for each circuit Instead of sharing a neutral for every 3 circuits and 1 ground per pipe. This will be used for point of sale equipment and computer loads.
Some of the ones I've done you can share a neutral, some you can't. It just depends on how it is speced.
Clean power has its own transformer (K-factor or an non-linear type). A clean power panel (which is nothing more than a regular panel with a 200% rated neutral). And if its true clean power it will have one neutral for one circuit (no neutral sharing). Non linear loads (switching power supplies, electronic ballast..etc.) cause harmonic distortion, mostly on the odd numbered harmonics.
Most affected is the 120/208Y system. Single phase 120/240 does not seem to have the same harmonic distortion problem.
Not not necessarily true, that may be some engineers solution to trying to obtain "clean" power, but if the equipment causing the power issues is fed from your xmfr, 200% pnl, oversized neutral, the "dirt" is still there. The fix for a PQ issue depends on what the issue is.
The most common source of poor power quality are neutrals grounded down stream from the main N-G bond, the fix for this is clearing the short(s).
Single phase does have harmonic issues, but they do not have triplen harmonics, that is additive issues that result in possible overloaded neutrals.
In 30 years of doing PQ issues, and 100's maybe 1000's of investigations, I have only seen a handful of problems with harmonics. Typically the issue is not when the system is fed from the utility but when the source is a standby generator.
Most of the issues with harmonics when fed from the utility were in the really days of electronics, PC's, VFD's, with overloaded transformers.
To my knowledge (old memory) I cannot remember ever having neutral issues with any lighting panels.
Over time,in my years here at Ford people have blamed a lot of malfunctions on dirty power. That I know of we just keep building cars and nothing changes. I don't know what is is. I think about the hetrodyning of different frequencies... if the offending frequencies have enough power to affect each other, I can see the possibility of creating circuits that would eliminate certain problem cycles.
As these terms are not defined in IEEE Dictionary of Standard Terms I would bet your foreman has only his interpretation, as you can see from this thread there is no REAL consensus as it means different things to different people.
Myself I NEVER USE the terms, clean power or dirty power when discussing power quality (PQ) with customers. Though I have seen the terms (mostly "clean ") utilized on drawings. But often the engineers do not know what they are discussing only what they hope to achieve which is a project with no equipment operational issues, to achieve this they try a variety of installation practices many that have worked in the past and there fore they utilize again. Not because of sound engineering but because the practice SEEMED to work.
I say seemed to work because there may not have been any issues to begin with. As noted many engineers spec IG circuits, there is NO evidence that IG buys anything in the field of PQ. It is a good practice for electricians as it increases work and job cost, but for PQ there is NO advantage. As a matter of fact most IGs systems I have seen are not NEC compliant or introduce more issues than they are suppose to solve or leave the system with un-grounded circuits or result in multiple grounds on the neutral or, or, or................
This may be what you are dealing with, as the two types of circuits require separate conduits.
As these terms are not defined in IEEE Dictionary of Standard Terms I would bet your foreman has only his interpretation, as you can see from this thread there is no REAL consensus as it means different things to different people.
Myself I NEVER USE the terms, clean power or dirty power when discussing power quality (PQ) with customers. Though I have seen the terms (mostly "clean ") utilized on drawings. But often the engineers do not know what they are discussing only what they hope to achieve which is a project with no equipment operational issues, to achieve this they try a variety of installation practices many that have worked in the past and there fore they utilize again. Not because of sound engineering but because the practice SEEMED to work.
I say seemed to work because there may not have been any issues to begin with. As noted many engineers spec IG circuits, there is NO evidence that IG buys anything in the field of PQ. It is a good practice for electricians as it increases work and job cost, but for PQ there is NO advantage. As a matter of fact most IGs systems I have seen are not NEC compliant or introduce more issues than they are suppose to solve or leave the system with un-grounded circuits or result in multiple grounds on the neutral or, or, or................
They do not require separate conduits, except if sepc.'d or based on conduit fill.
I'd say it's more like the difference between the young spry eager kid choosing to go into politics because he wants to better the world around him and the middle aged burned out guilt free greedy lawyer that is in politics because he gets perks off the common mans back.
Round here clean and dirty get thrown around all the time. Clean is always the IG panels or 200% neutral panels. Makes people feel better that their power is supposedly clean. Dirty will be used for convienience receptacles and non-computer items. As has been pointed out, it in no way mitigates PQ issues.
I think the whole 'clean power, dirty power' thing was invented by engineers so they could look like they actually knew something, plus it drove the cost of a job up, thus more money for them.
I had a conversation recently with Steve Albini who owns an unbelievable recording studio here in Chicago. He was telling me about a problem they were having with an unwanted noise in their system that was showing up in the recordings. He has a chemical ground, isolation trannys, the works. His tech assistant rigs up a portable amp, headphones and antenna and walks the neighborhood. On and off for two years he is pinpointing the source of the noise. He finds out that there is a copier with a bad power supply in the third floor of an office 6 blocks away. Electrical Audio even footed the bill to have them fix it. Sounded more like an RF problem, but still best troubleshooting story I've heard in a while.
There are power quality issues, usually related to improper grounding, something harmonics, sometimes voltage drop. But the amount of money spent on equipment to mitigate these issues would be better spent on proper engineered installations.
Transients can be devastating to electronic equipment, hell to distribution equipment if the magnitude and duration are sufficient.
This does not mean data centers and the like do not need to spend money for UPS, to minimize primarily from power outages and sags.
That is exactly what I am talking about. You must keep your mind on your work. You'll never catch me looking at one of those videos. When at work I am very intense and just want to get the job done. No time for that garbage. When I was younger I could have been tempted to stray and watch but, even then, I would only watch until my arm got tired.
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