Back EMF harmonics threaten the grid

| The solution, of course, is to suppress harmonics."

Show schematics of solutions (don't you just hate the buzz word).

This lack of information is not worth the discussion. Most Utilities that I am aware of have started charging customer for anything less than 85 power factor. Forcing the maker/user to fix his problems. I know of one utility that will disconnect you if you go below 80 pf.

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Yes, thats about the only option the utility companies have. The user in the end is left with options to put pf correction on any high VARS equipment in order to reduce that charge from the utility company. The odd ball harmonics issues are another situation the user can do nothing. the manufacturers of these items (PC power supplies for instance, in most but not all cases, will have to come up with cleaner ways to get what they need from the grid,,,and that will be a selling point to end users as it will help then reduce their pf charges.

So its all solveable. Recognition of the issue while not a mystery to the utility companies is still a mystery for many EE's apparently, even those working for the utility who are aware only of parts of the problem..VARS in this case......but were fully not aware of harmonic distortions/backEMF into the grid as the article discusses.

Phil Scott

Harmonics and back EMF are not the same thing. Period. You have yet to provide a single reference that supports that claim. Any you never will, because none exist.

Charles Perry P.E.

Charles you MUST get your friend Daelstrom under contol...he has been getting a clue and no has posted that emf harmonic feed backs while not at the predicted 50% level yet are in the

Now charlie...THATS progress... just think charlie, even though the posted reference is 7 YEARS! (gasp) old... the laws of physics STILL have not changed.

Newton would be edified as well.

Regarding the rest of your...er spin jobs...I will be addressing those as the hole you are digging for yourself gets deeper and as you reach critical mass... addressing each blurp and fart has been tedious.

See Daelstrom for his latest in the other tread... that was Great (gggg)

Phil Scott

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emf harmonics? New term you just invented? Hahahaha.

Charles Perry P.E.

You are an idiot who cannot read. I have said, and still maintain that back emf from induction motors is NOT a concern for utilities. Harmonics are a concern, but are in NO WAY related to emf. Harmonics from induction motors are almost nonexistent and not a concern. The harmonics from motor drives are a concern, but they are in no way related to emf.

Never denied harmonics, did deny emf as a concern. Harmonics are not much a problem at this point either. We have not seen the huge increase in distortion that was predicted several years ago. Of course my access to hundreds of monitoring points across the country mean nothing to you. I am sure in your special world, harmonics are bringing down the power system every day.

You will never post a relative article. You will continue to change your definition of emf until it suits you. Unfortunately, the rest of the world disagrees with your definition(s).

Actually, I did not say the study was bogus. I pointed out your error in stating that the article covered emf.

You never will.

As I have asked before, please post one credible piece of evidence to support your claims. Just one. I have posted many, all major engineering texts, that dispute your definition of emf. You have posted none in support. Oh and don't say it is all about harmonics. That is just your latest spin. Back emf, emf, are what you claim are affecting the grid. Prove it. Harmonics from ASDs, pc power supplies, or other power electronics devices are not emf, never have been, never will be. You need to post at least one reference of your definition of emf.

Charles Perry P.E.

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Stunning...simply stunning. I am breathless. Dear NG reader... amazing isnt it? Charlie is a PE too.

Phil Scott

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Yes, and he is correct. You haven't posted any credible tie between induction motor emf and harmonics. You persist in twisting our position into one of "harmonics don't exist" even though we have repeatedly corrected your misstatements. You persist in using the term 'back emf' in some vague way to include all of electro-magnetics instead of the clear, concise definition of emf that is given in a number of engineering texts on the subject.

What truly is amazing is your ability to completely ignore every credible engineering and physics text on the subject and your ability to mis-interpret even high-school level texts describing the issues of harmonics.

daestrom

Another LIE!! I did *NOT* say they are in the 25% range. I said they were

And after 7 years, the problem of harmonics destroying the grid and consuming an ever increasing amount of power *STILL* hasn't come to pass. The prediction was woefully wrong then, and it is still wrong.

And harmonics are *still* not caused by induction motors. Unlike your silly extrapolations of an article describing one source of harmonics.

daestrom

Well at least we have progress both you are charlie are admitting that induction motors can adversely affect the grid significantly. What else can a man ask?

You may continue to assert that harrmonics are not an aspect of EMF you like and spin that 40 different ways.

the basic facts and industry experience and detrimental harmonic feed back, other detriments from motors drawing amperage out of phase with voltage remain.... and yes indeedie you can continue to try, to parse these terms apart as though these operate in isolation...

and some will agree.... you should recruit these to yer cause here.

Phil Scott

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Good going...congratulations...nice hair split... can you elaborate on the actual figures then and why you chose 25% as a marker, instead of say 5% for example?

Enquiring minds want to know. btw the figger varies regionally, and more on local grids...and with time. So any single figure stated is nothing more than a broad shoot scope of the range of such issues... A grid may have 5% or less harmonic distortion...or the same in pf losses at one hour...and 5 times that an hour later... and it varies line to ground in most cases, by the minute.... how do I know? Ive spent 40 years being there and metering such things, nation wide in all sorts of weather for all sorts of clients... unbalanced power is the utterly pervasive rule...disasterously unbalanced power goes to epidemic levels in most cities in heat waves... its a non secret.. that that mess has many many different causes, power factor issues, harmonics issues, various combinations...impedance and capacitance isssues...

Attempts to say its just this or that single thing ...or non existent ....are bogus...and anyone of competence in the business can see that clearly...does see it clearly...owns the test instruments...and advises his clients accordingly.

so what is it with the 25% figger you so loosely tossed out... did you really mean 2% just to be flapping your face? Nah. We both know what the deal is.

You are just trying cover your and Charlies asses...and its too late for that. so tell me... what was up with yer 25% toss out number? Was it all smoke? or did you mean it? or what?

Phil Scott

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Charles- Mr Scott has his own definition of emf and back emf which are contrary to what is in established literature and usage. He uses emf for "Electromagnetic forces." however, even there his definition is at odds with usage. His forces are voltages and currents. On the basis of his reasoning, a light bulb will produce emf. He also seems to have his own definitions of VARS etc. The study that he refers to is simply a rehash of old stuff at the trade level and is, in fact an advertisement for harmonic filters. Note that he has not given any reference to support his position and is adept at misreading what other's say.

I smell troll.

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Oh please... a light bulb produces nothing it is a pure resistance, there is no reactance in that case.. motors and transformers produce a reactive back force. ...for a while there I thought you were going to be straight with me..

You can do a lot better bud

Phil Scott

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--------- Reply was expected: A motor draws current and so modifies voltages. A light bulb draws current and so modifies voltages. If one uses your definition of back emf- then this is what you have been implying.

If one uses the standard back emf definition- true- that does require a d(phi)/dt -i.e. transformer or speed voltages and this doesn't occur in a resistor.

Are you now getting in line with the rest of the world and admitting that the standard definition of "back emf" is the correct one.? -- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer

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with a motor you have reactance and back emf issues. You have neither with a light bulb. Voltage does not drop on a single light bulb as long as the grid has the capacity. So there is no effect from the bulb back onto the grid.

You three have demonstrated your intellect and characters here. For better or not... others see this. It is not for me to comment further.

Phil Scott

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----------- The fact that the light draws a current does imply that there will be an IZ (voltage) drop in the lines as well as power losses. That is fact and is all that I implied. A motor draws current so that there will be an IZ drop in the line as well as losses. Also fact. I said nothing about how big the effect is - that is also a fact. With your private definition of emf - the lightbulb fits as well as the motor. That is the point.

The fact that a lightbulb does not produce a back emf is noted in my second paragraph below. Are you having reading comprehension problems? See d(phi)/dt (or d(Li)/dt or rate of change of flux linkages)

Oh yes, if it is harmonics you want, I'll gladly feed my light bulb through a triac. No reply needed.