Safety Ground Conditioning

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mgalusha

Re: Safety Ground Conditioning
« Reply #60 on: 16 Aug 2013, 05:09 pm »
Excellent design, excellent implementation, excellent data.

Poor wrap-up.  I disagree with the descriptor "semi".. :thumb:

Thanks John.  :oops:

Note*: The DENO isn't made for being in the circuit mgalusha has it in, if anyone is reading this and curious. It basically doesn't work in that condition. It's meant for ground (earth). 

Obviously but exactly how would you go about measuring the Z vs I? Please propose a viable alternative. Since you already have been using them and have not presented any data, I suspect you don't have one.

Folsom

Re: Safety Ground Conditioning
« Reply #61 on: 16 Aug 2013, 05:13 pm »
You're right, I asked for one :lol:

I was thinking something like wiring a smaller 20a breaker into a (much) larger one, then producing a load (fault) that would obviously trip a 20a breaker, and using the DENO in it. It'd take a little construction, it'd be empirical. It'd be setup and performed by an electrician that has very extensive experience with conditions that supersede anything ever mentioned on here. But I don't see the point in doing it since everyone has come to the conclusion that they are safe.

I assume someone else on here finds the progression of this thread amusing. "I trust code, and not the people selling individual pieces that have to meet code for importing and selling, but I do trust made devices that are certified with code stickers/silk screen" ...... "wait it's ok"

jneutron

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Re: Safety Ground Conditioning
« Reply #62 on: 16 Aug 2013, 06:14 pm »
You're right, I asked for one :lol:

I was thinking something like wiring a smaller 20a breaker into a (much) larger one, then producing a load (fault) that would obviously trip a 20a breaker, and using the DENO in it. It'd take a little construction, it'd be empirical. It'd be setup and performed by an electrician that has very extensive experience with conditions that supersede anything ever mentioned on here.
A few points.  Sounds like a reasonable test, you can use varying lengths of #12awg romex to change the fault current peak, like 2 feet out to 100 or so.  Just be careful in breaker selection.  Make sure you're using a 10 kiloamp rated breaker, and make sure the panel board rating is compatible with that.  Industrial systems may not have the same bolted fault limit that a consumer home would.  Utilities control the fault current max to homes, but set industry for best efficiency.

If you have a clamp-over current probe, you can scope and save the fault current to determine the peak.

But I don't see the point in doing it since everyone has come to the conclusion that they are safe.
Actually, the conclusion is that the reactive drop does not allow lethal voltages to be presented to the chassis as a consequence of core saturation.  That is only one concern.
What cannot be concluded is the fact that they are safe in the application for 20 ampere breakers under various fault conditions.  That is what you as a manufacturer should demonstrate prior to selling product.  Positive test results would be a great selling tool.  Negative test results help you immediately.

I assume someone else on here finds the progression of this thread amusing. "I trust code, and not the people selling individual pieces that have to meet code for importing and selling, but I do trust made devices that are certified with code stickers/silk screen" ...... "wait it's ok"
While slanting the progression of the thread with a skewed view may amuse you, the facts are different.

1.  A reactive device was proposed to be inserted into a safety bonding circuit to eliminate ground loop problems.
          Breaking into the safety ground and inserting a reactive component is extremely dangerous if the "fix" is incapable of clearing the breaker, dangerous if the chassis
          potential is allowed to exceed lethal levels, and is dangerous if the integrity of the connection cannot be guaranteed for the life of the equipment.
2.  A link to the device was given, and the data from the manufacturer did not indicate control of lethal voltages, only that it was a reactive device.
          Further discussion ensued on how circuit breakers work, what criteria is needed for controlling chassis potentials, and how long the nominal reactances cited by the
          manufacturer would take to clear typical 15 and 20 ampere breakers.
3.  Further discussion on application ensued and test data generated by participants was presented.
          A believed to be design feature of the device, extreme core saturation, limits the reactive voltage drop of the device to 4 volts when driven at 4 times the rated current.
4.  Now it is being stated that the device is safe because the drop is 4 volts max at currents tremendously small with respect to fault currents.
          The manufacturer does not present data in support of the device surviving fault conditions, nor how to connect it in safely.

Trust code?  It is not a case of trust.  It is a case of use but verify.  I follow code as I wire a 10e+9 dollar machine and at home during reno, but I always examine the code and the application.  Code updates every 3 years, and some of those changes are a result of people like me notifying the NFPA about errors we find.

Trust people selling individual pieces?  Only if the pieces are certified for use in the application.  The vendor's datasheet is severely lacking in fault current tolerance data (which is the defining parametric for this safety device), reactance vs ac current, ampacity curves for current vs time, and detailed direction on how the connections to the device should be made which remain safe for the life of the product.

Trust things certified with a sticker/silkscreen?  That is the entire purpose of NRTL's.  Verification that the product has been made consistently using a process and materials of known quality such that the product will provide the expected results.  I expect that of medicine, food, airbags, and all my electrical equipment.

And there has been no "wait, it's ok."

Several hurdles have been cleared, but the race is only half over.

Trying to characterize safety concerns in a non engineered application of a safety circuit as ""much ado about nothing"" does nothing to support your reputation.

Solid engineering on the other hand, does.  I hope you do the tests if you are going to use the product.  I'm more than ready to assist if requested.

John

 

Folsom

Re: Safety Ground Conditioning
« Reply #63 on: 17 Aug 2013, 04:15 pm »
I don't think anyone is using the DENO as a ground loop elimination device.

We can talk more when I get a breaker, or set one up for independence from the panel with the larger (10 kiloamp) breaker.


Speedskater

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  • Kevin
Re: Safety Ground Conditioning
« Reply #64 on: 17 Aug 2013, 06:24 pm »
'Salis' that (10 kiloamp) is the breaker's 'Interrupting Rating'.  That means when something really bad happens with the power company equipment and the high-voltage line gets connected directly to your house.  Under these conditions, thousands of amps are flowing into your house.  So this rating means that the breaker will still trip with all this current flowing through it rather than failing as a dead short.

Folsom

Re: Safety Ground Conditioning
« Reply #65 on: 17 Aug 2013, 07:54 pm »
'Salis' that (10 kiloamp) is the breaker's 'Interrupting Rating'.  That means when something really bad happens with the power company equipment and the high-voltage line gets connected directly to your house.  Under these conditions, thousands of amps are flowing into your house.  So this rating means that the breaker will still trip with all this current flowing through it rather than failing as a dead short.

And? I'm just agreeing with jn that I'll use one that is rated for that. Most of them are now anyways. The larger one refers to the actual amperage rating for use and trip (in-circuit) that is exceeding the 20a test one substantially enough.

Speedskater

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  • Kevin
Re: Safety Ground Conditioning
« Reply #66 on: 17 Aug 2013, 09:23 pm »
Oh, sorry.  I saw that (10 kiloamp) number out of context and thought that you were talking about getting a huge breaker.  If you have a spare breaker and a magnifying glass you might be able to read the very fine print for the 10kA rating.  But I think that all the breakers that fit in your breaker box (panel board) have the same rating.

jneutron

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Re: Safety Ground Conditioning
« Reply #67 on: 19 Aug 2013, 01:04 pm »
I don't think anyone is using the DENO as a ground loop elimination device.
Actually, that is the only reason to ever consider using the device.

The biggest problem caused by safety ground is the creation of a low impedance loop when independent components are hard wired together in an attempt to share a reference node for the audio signals.  That loop is capable of trapping time varying magnetic flux being created by the AC delivery system and the system itself.  Faraday's law of induction shows the reference ground wire will not have exactly the same potentials with respect to each other as a consequence.

The gist?  Insertion of a reactance in the safety ground is NOT "conditioning" the AC power waveform, it is affecting the ground loop currents which can alter the sound of the system.

This device is only one type which is used in attempts to control that loop and the resultant current flowing in it.  Misguided attempts at using 1 ohm or 10 ohm resistors, inductors, diodes to break the safety ground may solve the immediate concern of loop currents, but they compromise the safety of the system.  From what I can see, this unit is the best I've seen for this function, but there is still work to be done.

The supreme requirement for the safety bonding circuit is for it to be totally effective for the life of the equipment, not the life of the owner..
We can talk more when I get a breaker, or set one up for independence from the panel with the larger (10 kiloamp) breaker.

I read this the same way speedskater did.  That of a very very large circuit breaker with a remote operator to rack the puppy, and a Back to the Future "Darth Vadar from the planet Vulcan" suit.  I guess we are all on the same page now...the 10 kiloamp rating is the surge the breaker is supposed to be able to survive without a containment failure (blowing up).  The standard is consistent with what the power company will allow into the residential system, so that there are no arc flash incidents.

I recommend the test be performed using a 20 ampere breaker mounted into a 200 amp residential loadpanel.  I suspect this is one of the larger service panels used in residential application.

I do not know what the European utilities set as the maximum fault current that can be delivered to a residence there, so cannot say if the design is adequate for US residential 20 amp breaker time/current curves.  I also do not know if the saturation breakpoint is sufficiently high for use in pro equipment, as Whitlock has measured AC ground loop currents at up to 58 milliamperes AC.  Use of these devices in that environment would render the low current isolation ineffective.

jn

Folsom

Re: Safety Ground Conditioning
« Reply #68 on: 19 Aug 2013, 03:16 pm »
When does the 2mh version (25a) saturate? It might be better for places like studios and what not.

Getting rid of loop noise is good, but so is eliminating anything not 60hz. Ground noise has been associated with making a difference on digital equipment. (I don't think we should get into this too much right now)

My dream Halloween costume is an authentic Darth Vader costume but... I've got no interest in close exposure to things like electrical flashes given that within a certain proximity no suit, Sith or not, will stand up to it.

200a is a good sized one in the US. Give me a few days to see what I can organize.

jneutron

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Re: Safety Ground Conditioning
« Reply #69 on: 19 Aug 2013, 03:36 pm »
When does the 2mh version (25a) saturate? It might be better for places like studios and what not.
If one assumes that the inductance is proportional to the number of turns squared and they use the same core, then half the inductance would require 70% of the turns. (1/sqr2).

The magflux is proportional to NI, so the current required for the same effect would go up as the square root of 2, or 1.414.

But remember, the idea is to lower the ground loop current.  Lowering the inductive reactance of the element will raise it.  You want higher inductance, but you want that higher inductance component to still survive operation under the upper line of the breaker clearing  curve.

Getting rid of loop noise is good, but so is eliminating anything not 60hz.
I have already detailed ad nauseum the concept of odd harmonic modulated and non modulated haversines and music content making it into the ground loop and coupling to the signal path..that is all non 60 hz.

My dream Halloween costume is an authentic Darth Vader costume but... I've got no interest in close exposure to things like electrical flashes given that within a certain proximity no suit, Sith or not, will stand up to it.

Ah, some explanation.  In the Back to the Future second film, Marty wore a 40 cal rated arc flash suit, called himself Darth Vadar from the planet Vulcan.  The suit is rated for an electrical flash at the 40 cal level.
200a is a good sized one in the US. Give me a few days to see what I can organize.
Me, I'd just go home to do it.  Seems you're going to sell the product, eh?.

Good luck in your endeavor.  Be careful.

edit:  I graphed mgalusha's data log-log.




jn

Folsom

Re: Safety Ground Conditioning
« Reply #70 on: 5 Sep 2013, 12:40 am »
Reactance value at 60hz, direct information from the factory.

DENO-25-0001 and DENO-40-0001 => 1.5 Ohm
DENO-23-0001 => 0.75 Ohm

They also noted zero concern with breakers.
Inductance they are rated at goes from 50-300khz.

Occam

Re: Safety Ground Conditioning
« Reply #71 on: 5 Sep 2013, 01:37 am »
Reactance value at 60hz, direct information from the factory.

DENO-25-0001 and DENO-40-0001 => 1.5 Ohm
DENO-23-0001 => 0.75 Ohm

They also noted zero concern with breakers.
Inductance they are rated at goes from 50-300khz.

Good Grief! Are you impressed that Schurter knows how to use a reactance calculator?
Direct information from the factory?????
http://www.electronics2000.co.uk/calc/reactance-calculator.php
put in 60 Hz and 4 mH and mirablie dictu! you gets 1.508 ohms

Quote
They also noted zero concern with breakers.

Who cares?
The ability to find a reactance calulator and plug in numbers doesn't merit credibilty on safety issues in North America, that, and the fact that only the DENO-40, which isn't imported to North America, would be their only offering rated to 'clear' a breaker from a faulty 15 amp appliance plugged into a perfectly ordinary 5-20R outlet, as defined by their own documentation. FWIW, YMMV

Folsom

Re: Safety Ground Conditioning
« Reply #72 on: 6 Sep 2013, 09:27 pm »
Relax Occam. I'm not "impressed". That's just what they replied.

If anything I'm disappointed that they didn't give details about how they react in a fault in this reply. But I can say that without any word of caution or concern they are fully liable for fault of a properly used DENO. That is important, too.

A test is still in order. It'll happen.