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14 % Harmonic Distortion at residential customer

14 % Harmonic Distortion at residential customer

14 % Harmonic Distortion at residential customer

(OP)
I have some high end audio equipment that displays the distortion of the incoming power.
My incoming power had always been between 2% and 3% distortion. Since a storm 4 weeks ago it has been 14% distortion. I have called LIPA (Long Island Power Authority) twice and have gotten the runaround. It seems that as long as my "appliances" are functioning, they are not interested in one residential customer's whacky complaint.

2 questions;

1.  Do I have the right to expect much lower distortion power from LIPA?
2.  If so, any suggestions on how to get their attention?
 
Here is a picture of the incoming waveform:
[IMG]http://i706.photobucket.com/albums/ww62/st50maint/untitled.jpg[/IMG]
 
 

RE: 14 % Harmonic Distortion at residential customer

Incoming what waveform?  Voltage, current?  Certainly not power.

RE: 14 % Harmonic Distortion at residential customer

(OP)
The waveform is of the voltage.

RE: 14 % Harmonic Distortion at residential customer

IEEE Std 519, IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems has limits for utilities which generally limit the voltage distortion to 5%.  This standard is a recommendation, not a legally binding requirement, but you should try to get the utility to meet its requirements.

The flat top on the voltage waveform could be a result of a large amount of distorted current from switched mode electronic power supplies causing voltage drop through the service transformer.  Switched mode power supplies draw current only during the middle of each half wave.  Was your transformer replaced in the recent storm?  Maybe the replacement has a higher impedance than the original.
 

RE: 14 % Harmonic Distortion at residential customer

It could be that, after the storm, your neighborhood is now on a different feeder from the LIPA substation than before, or from a different substation. The overhead line distribution system in the USA is flexible in that pole top switching can be done to change customers easily to another source, unlike cabled systems where that is difficult.

If you are near the electrified portions of the LIRR, it can be that harmonics from the silicon rectifiers in the DC substations are appearing, they will however vary with the load current drawn by the trains.

Here in my city in Europe, harmonics from the rectifiers feeding the rail system are clearly hearable at consumers near the grid substations, as well as the variations due to the load changes. Even in fan motors and audio systems.

rasevskii

RE: 14 % Harmonic Distortion at residential customer

It may be that people you contacted just didn't understand the complaint...  Usually utilities are pretty aware of and responsive to power quality issues.  In a utility that size, I'd guess there are a half dozen people charged with u=investigating PQ isssues.  These usually occur with commercial services, and their focus will likely be the same, so it may take a bit more effort for a residential customer to get their attention.  

If this was presented as a 'distortion' issue, it likely didn't ring any mental bells for the receptionist, and it didn't wind up in the appropriate pigeon hole.  I'd write an e-mail making a power quality complaint.  If no response, send a copy to the PUC.

This is probably not creating a problem for you, but may be indicative of an incipent problem on their system.

RE: 14 % Harmonic Distortion at residential customer

It depends on what contract, in writing, do you have with the utility company.

Rafiq Bulsara
http://www.srengineersct.com

RE: 14 % Harmonic Distortion at residential customer

As was mentioned before, 5% voltage THD or less would be normal per IEEE Std 519.

How much current were you pulling with your high end audio equipment when you recorded this unscaled voltage waveform?

In calling LIPA again, I would reference this as a PQ issue.  The PQ folks deal more with harmonics and voltage distortion and should be able to check it out.

RE: 14 % Harmonic Distortion at residential customer

Chances are the problem is in your house. If you have a battery powered portable radio, turn it on and see if you hear loud buzzing noise at the low end of the AM dial, then check the high end of the AM dial. Nothing? Carry the radio to various rooms and see if you can detect the LOUD BUZZING noise.  Nothing? Then the noise is probably coming from the power company or one of your neighbors.

If you do hear the buzzing, turn off the main circuit breaker in your breaker panel in your house.  If buzzing continues with main breaker off, problem is from the power company.  If buzzing stops when you open the main breaker, close the main breaker, and open the other breakers one at a time until the buzzing ends. The breaker that is turned off when the noise ends is the problelm breaker. Turn that breaker back on and go to the area in the house fed by that breaker, and unplug or turn off each electric device fed from that suspect breaker. If you unplug a lamp and the buzzing stops, the lamp probably has a bad dimmer.  If the problem is in the garage, it might be the door opener.  It might be a computer document scanner, or a new refrigerator, or an Obama light bulb.

RE: 14 % Harmonic Distortion at residential customer

This is clearly an LF harmonics issue and that will not be noticed on AM. Not even in the long-wave band, where frequencies are in the 100 - 300 kHz range as compared to the 180 - 3000 Hz range produced by these LF harmonics.

But not good and there may be a transformer running hotter than expected when voltage looks like this. Contact the utility PQ people. They should react to this.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: 14 % Harmonic Distortion at residential customer

(OP)
When the scope photo was taken, the audio equipment was shut off. The only items drawing significant current were incandescent light bulbs and the vacuum tube oscilloscope itself.   

The problem is not only in my house. I borrowed test equipment from work and tested my neighbor's house. I measured the same 14% distortion. I went to a delicatessen about 1/5 mile away and same problem. I then went to my mechanic about 1 mile away and his distortion was good at only 3%.


 

RE: 14 % Harmonic Distortion at residential customer

(OP)
The problem has been corrected by LIPA. Distortion now measures 2.6%. Thanks for the help.   

RE: 14 % Harmonic Distortion at residential customer

Keith,

Refer to the first post! poke

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: 14 % Harmonic Distortion at residential customer



Thanks Scotty.

So it was the delivered power and they fixed it.  Nice.
And nice sleuthing st50maint.

st50maint;  Did they happen to tell you what they did to fix it?

Keith Cress
kcress - http://www.flaminsystems.com

RE: 14 % Harmonic Distortion at residential customer

(OP)
No, LIPA did not tell me anything about the fix.  

RE: 14 % Harmonic Distortion at residential customer

(OP)
After 4 good months the problem has returned. I have had 14% distortion for the last 10 days. I am not looking forward to calling customer service. If any new readers of this old thread have any suggestions, they will be greatly appreciated.

  

RE: 14 % Harmonic Distortion at residential customer

(OP)
The first post was not formatted properly to show the picture. Here it is now.

RE: 14 % Harmonic Distortion at residential customer

Do you have your own grounding systems at home?

If there was no electricity there would be no internet. Good point, don´t you? :D

RE: 14 % Harmonic Distortion at residential customer

Even more flattened now. Looks like more SMPS have been added. But the transients at the end of the flattening seem to be gone.

Has the buzzing sound returned? I guess not.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: 14 % Harmonic Distortion at residential customer

Yuck.  That's hideous.

That picture should help get the point across and ultimately some quality recording equipment installed by the POCo.

Keith Cress
kcress - http://www.flaminsystems.com

RE: 14 % Harmonic Distortion at residential customer

Sounds like your best option is to move or become an Amish farmer.  On a more serious note, turn off all of your feeder circuits on your panelboard and then see what your getting.  This may clue you in to where the problem may be occurring.  If your THD problem disappears with all your feeder circuits off, then the problem resides from within.  Also, check your neighbor's service.  If your sharing a transformer with a neighbor, check out what his voltage THD is.  If you find similar THD problems throughout the neighborhood, then you have more ammunition to complain to the local utility.

RE: 14 % Harmonic Distortion at residential customer

(OP)
mmt019, Thanks for your suggestions. I have already done them. My neighbors also have the problem.

Here is the latest Email response from LIPA.

Thank you for contacting online services.
The initial investigation involved electric service securing the connections between the pole and the building structure.
This included checking and securing neutral and voltage connectors .
I have forwarded your information has been submitted to investigate electro magnetic field in the area.
Our interference personnel is now investigating the matter.

Ms Adams
Customer Online Services

 

RE: 14 % Harmonic Distortion at residential customer

Quote (st50maint):

After 4 good months the problem has returned.
I'd guess that there is some customer with a 'dirty' (i.e. nonlinear) load out there on the system somewhere. Possibly only on one phase. Initially, during restoration following that storm, this customer was switched onto your phase. And now when the complaints ensue, LIPA just moves him to another phase, whereupon those customers start complaining.

LIPA may know who the culprit is. But they don't want to cause trouble by leaning on this customer. They'll just go on switching him around until they find a group of customers that don't mind the buzz.

RE: 14 % Harmonic Distortion at residential customer

(OP)
5 days ago I went to a LIPA customer service office. The representative gave me a couple of names to call in the "Electric Construction" department.

The woman who answered my call actually seemed interested in my problem and said she would have the appropriate person call me back that day. I never did receive a call back. However, 2 days ago the problem was fixed. I now have 2.9% distortion.

I called LIPA back to thank them and hopefully find out what they did. The woman looked up the records for my address but did not find anything specific that had been done to correct the problem. So I do not know if my phone call helped or not. She did tell me to call back if it happens again.

Thanks for all the help on this forum.

 

RE: 14 % Harmonic Distortion at residential customer

This conversation or something like it probably took place. "John" and "Bob" are fictional employees.

Oct.2010- John- "What phase did you put BSPC (big@@@ single phase customer) on last night?"

Bob- "$%^^& I don't remember, it was raining down my back and I wanted to finish and and get back home.

Dec. 2010- John- "Bob, some guy is complaining about buzzing on his record player. Go see if maybe he is on the same phase as BSPC, and what you can do about it. I'm taking time off pretty soon for the holidays and don't want to hear about it then."

April 2011- Bob- "John, when I moved BSPC a few months ago, I put them on the same phase as my mother-in-law, We are going to have to do something."

John-"I don't care what you do, but don't put them on the same phase as MY house."

May 2011- John-" Bob, the record player guy is calling again. Maybe we can move your mother-in-law to a different phase, I'm getting tired of this #$%^".          

RE: 14 % Harmonic Distortion at residential customer

Right on!

Only - it wasn't Bob and John. I recall Wayne and Chuck having those conversations...

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: 14 % Harmonic Distortion at residential customer

st50maint;  Thanks for the come-back.  That's disappointing but at least it's fixed.

Gunnar are you sure it wasn't UP and Chuck?

Keith Cress
kcress - http://www.flaminsystems.com

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