Design a clean system from an EMF perspective

[Apogee]

I would be very interested to learn how to build the cleanest system possible from an EMF standpoint.  I'm hoping Bruce will jump in here and share what he's learned, but am also hoping there are others that have researched this topic as well.

If you were going to design an off grid system from the ground up to minimize potential health effects from dirty power, how would you do it and what components would you choose?  Also why...

I look forward to any info others are willing to share.

Thanks,

Steve

[BruceM]

Sure, this isn't too hard. EMC or the field of Electro Magnetic Compatibility is the EE field which covers this area, though of course concerning with equipment emissions compatibility, not biology. You can find textbooks on the subject at a University engineering library. It is not for the faint hearted, or easy reading, but it's not Voodoo.

Inverters and solar charger units, and battery chargers today all use switch mode power supplies.  The are light, compact, powerful, and relatively cheap for the kind so power they manage.  But they do generate a tremendous amount of EMI. By design, they could be greatly improved, at some expense, but right now there's no motivation for that.

The batteries and solar charger, inverter need to be located away from the house, which is not uncommon anyway, but if you haven't built it, I'd push it out 100 feet or better if practical.  But absolutely, positively, don't put it in the house, as distance is cheap and effective at reducing the high frequency magnetics that the PWM systems generate in operation.

So now the noisy gear is all in one space, away from the house and we need to clean up the emissions on all wires leading from the system, as they will carry this noise (conducted radiation) and then re-radiate it (emitted radiation) as an antenna.

High performance passive power filters are a very carefully designed series of inductors and capacitors.  The allow low frequencies (60Hz), but block and convert high frequencies (typically start at 10KHz to 2GHz) to heat, and shunt some of the energy to their required, high frequency capable earth ground.


The best filters to be found are surplus military grade, or new from Genisco in CA, or RFI Corporation on Long Island, NY.  There are a few other vendors, too.   There are lessor commercial filters, which will provide at least some improvement, but I won't waste my time installing them.

AC inputs to the dirty room may need to be filtered, though you could skip the AC filter or go with a lessor filter if the AC line were buried steel conduit back to a generator shed. There are no meaningful high frequency emissions from a power cable in buried steel conduit.

The PV power must be filtered, as the panels will radiate quite effectively.  The filter gets mounted to the wall, and steel conduit must be used for the run to the PV array(s), or at least the first 40 feet. (Same rule would apply to a filtered AC.)  This is because, otherwise, the unshielded wire will pick up the emissions from the input wire to the filter (radiated emissions picked up by wire, coming conducted emissions, again.

The filtering of the inverter output is where you want to lay down the dough or be a good surplus scavenger with a  military grade facility filter, 13KHz to 2GHz, -100dB filter.  Those filter figures are somewhat bogus as the standard test is done with a 50 ohm source. If you put a 50 ohm power resistor in the line to the inverter, you'd get the spec'd performance.  But of course that would be a disaster, power wise. So the test lies and makes capacitive elements more effective than they really will be.  But starting with a -100dB lie gives you some headroom for reality.  

If your inverter power output is 2 hots and a neutral, you need a three element filter facility filter.  You'll want to run buried steel conduit to the home, to keep your clean power that way until it's as far from the inverter as the house is.

The use of steel siding and roofing on the battery/inverter building would be helpful in blocking emissions radiating directly from the equipment, and does not add a bunch of cost.  Foil backed drywall from US Gypsum, applied foil to the interior and with seams taped with foil tape does even more, if you're going for best, cheaply built containment.  Use a steel door with steel frame if you're going that far, and it should be a slab on ground, not raised wood floor.

With this arrangement, you have accomplished getting back to a power quality of the power company, in fact often much cleaner. Your homesite and outside areas are free of strong emissions. A typical off grid setup has some of the worst high frequency EMI situations that you would ever find in an on grid home. The FCC is phasing in emissions requirements for this equipment, but their specs are the sloppiest in the world, and are only concerned with telecommunications interference.

At that point, there are some things to do to make sure your house wiring doesn't have some problems such as two different circuits neutrals connected together in a big wire nut, which can cause dramatically elevated magnetic fields, but you have now achieved a clean off grid power setup that only a few homes in the world have today.

Grounding practice for the off grid setup is something I'll add later, not a big deal, just the age old, effective single point grounding (with extensions), with your  ground at the dirty power building, constructed to provide good high frequency grounding of your filters and the lead out steel conduits.  

For new off grid home construction, EMT conduit with compression fittings is best. It shields the wires, so that Dad's computer doesn't radiate all over the house when it's on.  In a cost constrained situation,  romex for most but  EMT conduit gets used for any dirty circuit like office/computer locations.

Selection of appliances and motors avoids the use of digital circuitry, and switching power supplies.  And you will be disappointed to know that your previous effort was half wasted if you the use compact or other fluorescent lighting in the home.  Even LED bulbs which use a SMPS in the base are a disaster.  One of the reason conduit is a good idea, is that down the road, LED panel lights and such could be operated cleanly off of DC.  Conversion of AC to DC at the bulb/lamp is just too noisey, from diode noise if nothing else.  The DC needs to be created and regulated in the dirty room, via buck/boost regulator, and then filtered, and run to conduit carried lighting circuits. This gives you the ability to deal with any lighting technology in an ideal manner

Now you're sorry you asked, right?  

Bruce

[Apogee]

Bruce,

Just wanted to say thanks for taking the time to share what you know.

No, not sorry that I asked.

Why not just run DC for almost everything?  I would think if one shopped carefully, one could track down the DC versions of almost everything necessary.  I'm thinking of boats where they run 32 vdc for almost everything.  One could wire direct, bypassing the power supply, to run computers, televisions and most kitchen appliances...

Am I missing something?  Just doesn't seem like it would be that tough.

Thoughts???

Steve

[BruceM]

What's out there for DC is pretty limited, so I wanted to address cleaning up a more typical inverter system.  The short form is filter inputs and outputs, on a budget go look at powersolutions.com. 

Another issue is that once you do anything with DC that involves motors or electronics, it's not DC anymore, it's DC with high frequency AC on top; in fact, the AC induction motor is the cleanest electrical motor there is- zero high frequency emissions.  So for a more conventional home, you really do want to just clean up the AC, though down the road some other voltage DC for LED lighting may be very helpful for energy reduction.  Thus my advise to use conduit for lighting circuits, or at least keep lighting separate.

For myself, I've designed a 120VDC system, which is mostly built now, with 12V also available in the home.  There's no switchers or PWM involved, just linear DC.  It's been a big project.

This handles my lighting, and is also used to power my custom rear projection computer/entertainment display/workstation, as well as shop lighting, and computer.  Some switchers will run off 120VDC, some need a little boost to 150V.

I only use switchers remotely, like in the shop for the laptop which drives the remote workstation projector via fiber and steel conduit with substantial filtering to keep my 120VDC clean.  Keyboard, trackball are custom, no processor, no active matrix strobing.  The keyboard problem (I don't last long with one in my lap) took me almost a year to solve.  Lots of failures to learn from there!

Bruce

[mobile_bob]

Bruce:

because my homesite is on a hillside, i have been giving some thought into
cutting back into the hill and burying a 20ft shipping container to house the complete
power generation system, battery/inverter, control system, basically everything
and then bring the power underground to a standard entrance at the house.

of course doing the filter thing before it enters the house.

wood the steel container, "contain" most of the emi made within its walls?

i am not emi sensitive (at least as of yet), but have other reasoning to keep my emi footprint to a minimum.
as well as my heat signature, carbon output and sound radiation.

bob g

[WGB]

Bruce:

because my homesite is on a hillside, i have been giving some thought into
cutting back into the hill and burying a 20ft shipping container to house the complete
power generation system, battery/inverter, control system, basically everything
and then bring the power underground to a standard entrance at the house.

of course doing the filter thing before it enters the house.

wood the steel container, "contain" most of the emi made within its walls?




i am not emi sensitive (at least as of yet), but have other reasoning to keep my emi footprint to a minimum.
as well as my heat signature, carbon output and sound radiation.

bob g

LOL, Bob you sound as paranoid as I am!

[mobile_bob]

when you set out to build out in the country, are known to be a right wing conservative antiglobal warming gun loving anti liberal sort of guy, the left no longer refer to your place as a rural home but rather a "compound", so

i figure if i try to mitigate my footprint, that alone should drive them nuts trying to figure out what the hell i am up to out there.

my hope is to make it where i have no visible means of support as well, have already decided should the government still have
two nickels to rub together to send me a SS check, i will have a po box set up in a neighboring town maybe 30 miles away
rather than have it delivered to the local PO that is a mile away.

that should really get em talking,

"hell, he don't even get any mail"!!!

"what the heck is he doing out there"

the county is supposedly useing a remote flyover drone to take pictures of questionable activities now
and i plan on doing my level best to give them something to sit around and  ponder about.

who knows, maybe i will get into remote control aircraft too, and build myself a small airforce of fast response
fighters!  ya... thats the ticket!

now that would be fun, wouldn't it?  i nice summer afternoon, out on the deck remote control in one hand
and a beer in the other.

not particularly paranoid, just got a twisted sense of humor.

wait till you see what i have in mind for the drive from the highway up to my homesite. 

maybe i will also grow some of that evil weed in my greenhouse, you know the stuff "tobacco"!



bob g

[BruceM]

We have a few militia groups out here east of Snowflake, the small town gun store owner is doing VERY, VERY well, with what he thought was going to be a modest hobby -retirement business.

Also what I call the "guns and Jesus" survivalist groups, ultra conservative, bible quoting, big on explosives and buried supplies and stockpiles of weapons and ammo.  Seems an odd mix of philosophy to me, but then I'm sure I seem even more odd.  There's a large former hippy group who are a lot of fun, and the old bikers group, and where I live, the disabled with chemical injury group.  Oddly, we all seem to get along pretty well, there has been some cooperation on community issues like developers wanting to put megawatt windmills within 500 feet of people's homes.  I know some nice folks I enjoy in every one.

Yes, a steel container is a decent shield room, often much cheaper and easier to do than building a lesser structure. By putting an aluminum plate on one wall, and mounting filters to it, and a good ground, you'd have a first class setup.   Cleaner power won't hurt you, and if Milham's cancer cluster research is repeated in other dirty power schools and homes, I think we'll see that dirty power really is the engine driving the cancer and autoimmune epidemic that may bankrupt our economy, besides causing untold suffering.