# MF'n EMF Problem



## oldtimer (Jun 10, 2010)

rugger said:


> Hello to all, I have been lurking for some time. I enjoy the forum alot, very informative and thought provoking. We just finished the LV systems on a home, (phones & audio). We were not the EC on this job. The home is on top of a mountain, at the end of the road & utility lines. Approx. 1 mile. The service is 1-ph., 120/240, 400A. The well contractor installed a single to 3-phase converter to accomodate the 1000' ft. well for the water to the house. 240v1ph to 3-ph. fed from a 2p/20A CB. When the well comes on there is so much interference that the phones go all staticky (is that a word?) and the DSL (also on the phone line) shuts down completely. We have tested for just about everything we can imagine to find a cure. Last week the manuf. of the converter sent a man out to install a filter on the circuit. This seemed top help at the time but now the contractor called to say the problem is back. He said that the problem was eliminated when the CW Bond was disconnected. (they reconnected it). Any ideas to correct or isolate or determine the cause would be greatly appreciated. Thanks to all.


 I would check out the grounding for a start.


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## wildleg (Apr 12, 2009)

if you didn't do the electric or the well pump why is it your problem ?


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## hardworkingstiff (Jan 22, 2007)

FE Petro (makes water pumps and fuel pumps) came out with a controller that converted single-phase to 3-phase to drive their variable speed fuel pump (this was over a decade ago). There was so much noise that the communication circuits to the fuel dispensers would lock up and go crazy.

FE Petro finally figured it out (took years). 

If I was in your shoes, I'd start with the manufacturer of the converter. See what they can do to help. 

Where is the converter mounted? If it's in the house near the service, maybe you can have someone move it out near the well pump, moving the controller for us in the fuel business helped. We also found installing all metal conduit helped.

I also agree with the poster that asked why this is your problem if you can demonstrate that the interference is coming from the well pump. I think there are laws/rules about equipment not causing these problems.


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## micromind (Aug 11, 2007)

I suspect that the 1 to 3 phase converter is an electronic type, similar to a VFD. 

If so, the output isn't a sine wave, like you get from the utility. It's called 'pulse width modulated'. 

Where a sine wave rises and falls on a steady slope, PWM (pulse width modulation) is comprised of a series of full-voltage pulses. These pulses are timed so that there are few when the 'wave' is near the zero crossing point, and they're much closer together when the 'wave' is near its peak. 

Unless there's shielding involved, the pulses will interfere with any and all wiring in close proximity. Using shielded cable for the comm wiring will help, shielding the power wiring from the converter to the pump will help too. Both is better. Installing a load reactor near the converter will help some, but not very much. 

Shielding can be accomplished with shielded cable, or steel conduit. If using shielded cable, ground the drain wire at one end only, never both. 

Moving the converter out to the well will help a lot. There'll still be some interference in the single phase line, and if needed a line reactor can be installed. 

Considering the type of phase conversion, the length of 3 phase wire, and the close proximity to the comm wire, the interference doesn't surprise me at all.

Rob


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## mattsilkwood (Sep 21, 2008)

micromind said:


> If using shielded cable, ground the drain wire at one end only, never both.


 Why is that? I've never had anyone able to give me a straight answer on that. 

That is the way I was taught and that is the way I do it. But why?


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## RIVETER (Sep 26, 2009)

mattsilkwood said:


> Why is that? I've never had anyone able to give me a straight answer on that.
> 
> That is the way I was taught and that is the way I do it. But why?


You want it shielded to ground but not be a conductor of small currents?


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## hardworkingstiff (Jan 22, 2007)

mattsilkwood said:


> Why is that? I've never had anyone able to give me a straight answer on that.
> 
> That is the way I was taught and that is the way I do it. But why?


It is my understanding having it grounded on one end provides a path for magnetic fields to drain away (hence drain wire). 

If grounded at both ends you can set up a ground loop which will probably make things worse.


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## RIVETER (Sep 26, 2009)

Having it grounded only at one end keeps a magnetic field from being of any consequence.:thumbsup:


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## wildleg (Apr 12, 2009)

we have installed pulse modulated flame detection systems in hangars and other areas where if someone accidently landed both ends of the ground they would get interference that caused false alarms (don't know the exact reason but I would assume it's induced emf)


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## RIVETER (Sep 26, 2009)

wildleg said:


> we have installed pulse modulated flame detection systems in hangars and other areas where if someone accidently landed both ends of the ground they would get interference that caused false alarms (don't know the exact reason but I would assume it's induced emf)


Were they called "purple peepers"? At least that is what we called them. They operated in the infrared spectrum.


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## wildleg (Apr 12, 2009)

http://www.det-tronics.com/utcfs/Templates/Pages/Template-53/0,8062,pageId%3D2648%26siteId%3D462,00.html

(actually I think that model has some signal rejection features, but I think it was an older model that didn't and are more susceptible to the interference)


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## RIVETER (Sep 26, 2009)

wildleg said:


> http://www.det-tronics.com/utcfs/Templates/Pages/Template-53/0,8062,pageId=2648&siteId=462,00.html


Those are the kind that we use in the paint booths. The purple peepers I talked about were used to monitor the flame of a gas burner.


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## rugger (Jun 30, 2010)

Thanks to all for the replies. I guess I inherited the problem when everyone else threw up their hands. Checking the grounding was my first thought but it checked out fine. The manuf. blamed the ground also and had the well contractor drive 2 more ground rods. (no easy feat around here). Of course there was no change. We had them also bring a new converter but it did not help either. I had run a temp. ckt. (romex) from the breaker to the converter thinking that the proximity to other wiring might contribute to the interference. I ran it from a 2p breaker, the only branch breaker in one of the 200A Main disconnects (which are located on the inside wall opposite of the meter can), directly to the converter (about 15' away) with the ground tied to the Neut./Grnd. bus. Also no help. The manuf. was adamant and had us checking grounds and blamed the dry earth and blah, blah. Then, after hours of troubleshooting they come out and say "well there is this filter that we have for correcting this problem that we have never seen before". I was really PO'd.
I think relocating the converter to the well head, and running the ckt. in metal conduit will be my next step. That is a relatively easy thing to try. What are the Rf/EMF Filters for circuits like this? This cannot be an isolated problem with all the VFD's and similar equip. out there. Thanks again, I'll keep you posted.
Rugger


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## wildleg (Apr 12, 2009)

RIVETER said:


> Those are the kind that we use in the paint booths. The purple peepers I talked about were used to monitor the flame of a gas burner.


pic or link ? don't know what a purple peeper is.


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## RIVETER (Sep 26, 2009)

wildleg said:


> pic or link ? don't know what a purple peeper is.


I don't have a picture but we called it that just because it was that color. It mounted on a flange to a 1/2 in conduit (actually black iron pipe.) The pipe pointed towards the flame and monitored the presence...or not, of the flame.


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## RIVETER (Sep 26, 2009)

Actually, google Purple Peeper flame detector by Honeywell.


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## wildleg (Apr 12, 2009)

http://www.lesman.com/unleashd/catalog/combustion/combustion_honeywell_C7027MinipeeperUV.html

gotcha


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## RIVETER (Sep 26, 2009)

wildleg said:


> http://www.lesman.com/unleashd/catalog/combustion/combustion_honeywell_C7027MinipeeperUV.html
> 
> gotcha


Not that one . Did you check the other Honeywell site ?


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## wildleg (Apr 12, 2009)

http://customer.honeywell.com/honeywell/ProductInfo.aspx/C7012A1145

looks similar, but not quite as advanced as the detronics models. what kind of paint booths you use them in ? (how do they keep the face clean ?)


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## RIVETER (Sep 26, 2009)

wildleg said:


> http://customer.honeywell.com/honeywell/ProductInfo.aspx/C7012A1145
> 
> looks similar, but not quite as advanced as the detronics models. what kind of paint booths you use them in ? (how do they keep the face clean ?)


Automotive spray booths. We cleaned them infrequently. The spray booths are generally air balanced and any dirt, etc, gets sucked away. The purple peepers I spoke of were for flame monitoring. Just Google"purple peeper flame detector" plain and simple.


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## rugger (Jun 30, 2010)

Riveter & wildleg, why don't you guys PM each other about the incredibly interesting purple people eater. I am new here but it seems kind of rude to hijack a thead like that.


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## TOOL_5150 (Aug 27, 2007)

rugger said:


> Riveter & wildleg, why don't you guys PM each other about the incredibly interesting purple people eater. I am new here but it seems kind of rude to hijack a thead like that.


thats how this site goes. and seeing that they have 1000 times more posts than you... they can do what they want, within the rules of the site.

~Matt


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## wildleg (Apr 12, 2009)

rugger said:


> Riveter & wildleg, why don't you guys PM each other about the incredibly interesting purple people eater. I am new here but it seems kind of rude to hijack a thead like that.


I thought your solution was discovered ?


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## RIVETER (Sep 26, 2009)

Where, in the system was the cold water bond removed?


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## JohnR (Apr 12, 2010)

mattsilkwood said:


> Why is that? I've never had anyone able to give me a straight answer on that.
> 
> That is the way I was taught and that is the way I do it. But why?


Re: grounding at both ends.
As I understand it, and I could be somewhat off base.
If you ground at both ends, the shield turns into an antenna and pumps the emf or static into the electrical system. 

I believe this is partially because of the difference of potential from your starting point and the end of the circuit that is shielded.

The Difference between the "noise" that one grounded side "hears" combines with the "noise" at a slight time delay from the other end. 
The shield is not your equipment ground, it is only for noise in the system.


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