Author Topic: DIY Low EMF 5 step Sine Inverter  (Read 1248 times)

BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #45 on: August 21, 2018, 11:13:05 PM »
Yep, the power factor of the GTI (capacitor inputs) would likely goof up some generator-regulators.  Most AVRs are NOT RMS regulators, and will regulate AC true RMS voltage  lower when faced by this type of load.  (200V instead of 230)  Bob's ST-5 on harmonic would likely do fine. 

With a inductor (choke or reactor) above the critical value for filtering, there will be excellent power factor and no problem with voltage regulation by the generator head, regardless. 

I hope we hear from Bob soon- getting overrun by wildfire is very dangerous.







« Last Edit: August 21, 2018, 11:14:45 PM by BruceM »

glort

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #46 on: August 22, 2018, 01:32:34 AM »

I looked up the fires in the area, they are not good. Was hoping Bob could have posted by now he was OK. Seems there is a Fire right where my Aunt and Uncle Live which isn't far from Bob. I know they will be OK,  Uncle has a concrete tank on the hill full of water for running sprinklers and they are well away from any scrub. Only thing they would have to deal with a is a grass fire from the surrounding cow paddocks.  The fire will be down the road opposite them which is my namesake. 

There is heavy rain predicted in the area on the weekend.
Chances are they will be dealing with flash flooding by then knowing how the rain goes in that area. Just the same, I reckon the way half the state is burning and all of it is deep in drought, I reckon it will be the most welcome rain in a long time.

If it does not happen, I think the meteorological guys better shut the door and leave quickly.

glort

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #47 on: August 22, 2018, 04:42:10 AM »

I emailed Bob:

Hi David, yes still here. House still intact, fires still blazing and the wind has blown up again. Water bombing aircraft flying over as I type. Will post more later.

Bob

Good to know he is OK.

BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #48 on: August 22, 2018, 05:34:47 AM »
Thanks for the update!

ajaffa1

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #49 on: August 22, 2018, 10:03:27 AM »
Hey Guys, still here and still OK, I have just seen another two fire engines go past my home, that makes nine in the last hour. Looks like the fire service are throwing everything they have at this fire. The problem they face is lack of water due to the ongoing drought and very dry bush.

If we can stay safe till Friday we should get some rain, the first in three months. Hoping that will help extinguish some of the fires. At the moment We are sandwiched between two fires if the wind blows from the west or east we could be in serious strife.

Pray for rain, not just for us but for all those NSW farmers doing it tough.

Bob

glort

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #50 on: August 22, 2018, 10:22:43 AM »

I just looked at the weather.  I'm about 700K from Bob but what was predicted as a sure Downpour here the weekend has been revised to the possibility of a damp path.  ::)


Bob's area is forecast to have medium to high chance of showers and thunderstorm Fri and sat.
Unfortunately the wind is forecast to pick up again and become north easterly.
Sure hope the rain prediction holds true.  I think it's not been as badly needed for a long time and over such a wide area.

Where I am and where my father is as well seems to have some anomaly.  It will pour rain 1Km or less down the road but where we are, barely a drop if anything.  There is a weather station less than 3Km from me as the crow Flies and the difference in the rain that falls there and here is way too much just for my rain gauge to be out.... especially when the guy next door gets exactly the same tally as I do.

The rainfall for the majority of the country and the most heavily populated areas is for a Dry spring.
Not what anyone wants to hear atm.

ajaffa1

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #51 on: August 22, 2018, 12:24:08 PM »
Hey Glort, North easterly I can cope with, the fire to the west is much closer.

Rain in Australia is a strange beast, it`s all or nothing and very localized. I can get 100 mm in an hour while my neighbor gets next to nothing. I have seen the Nymboida river rise by more than 20 meters overnight when we do get proper rain. Always breaks my heart to see it run down hill and out to sea. We need to do a lot more to capture it for use in dry spells like this. A couple of good inland dams would provide us with water, hydro electric power and fishing. Got to be a win all round but the gubermint are too busy squabbling among themselves to make any decisions or useful investment. If you want to find the source of global warming it`s  coming from all the hot air and BS produced by the politicians. I wonder what the emissions are from all the journalists, analysts and TV presenters that hang on their every word? What a useless bunch of overpaid assh*les they all are. I retract that statement, assh*les are useful when you have the sh1ts, politicians, analysts and he media are not! >:(

Well, while I was typing this I got a phone call from a friend of ours who is fighting the fires. She tells me that we are not out of the woods yet. It gives me hope for humanity and enormous pride in the Australian people when a forty five year old woman is voluntarily fighting fires in the dark to protect me and mine. God bless her and all the firefighters.

Bob

tiger

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #52 on: August 24, 2018, 04:43:47 AM »
52 years ago tomorrow I was on my honey moon near Shaver lake California at her cousins cabin. under the eves were 1 pint mason canning jars upside down glued to the underside of the roof. The bottom metal screw on cap had a shot gun shell punched through it, the shot removed. I asked later what? they were filled with Borate and or baking soda. The 99 year lease from the forest service was expiring and they told the owners no renewal and no fire support any more. later a land trade was made and a volenteer fire Dept formed. they would not cover homes with the bombs installed. with the plastic bottles available now they could work even better with reduced risk to fire fighters. I was told a house fire starts under the Eves in a clockwise swirl, the bombs go off and the structure has another chance all be it slim. Maybe south of the equator the swirl goes counter clockwise? We have smoke from Canada BC and Olympics and Cascades, but nothing close. Wishing you all the best
Metro 12/2 ST 10 KW

ajaffa1

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #53 on: August 25, 2018, 12:22:36 AM »
Thanks Tiger, I`ll look into that idea. I have shot gun cartridges and mason jars, baking soda is cheap enough. I will run the plan by some of my fire fighter friends. I expect they will be horrified! :laugh:

Most house fires here start in the gutters. Burning embers fall on the roof igniting dry matter in the gutters, The fire then burns up into the roof space. A lot of Australian homes have sprinkler systems on the roof to fight this problem.

So far we have had lots of smoke and falling ash but no burning embers, lets hope the rain continues to fall and the wind keeps down.

Bob

BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #54 on: August 27, 2018, 08:23:31 PM »
I'm still working on that last 10% of my inverter install.  It's been really educational. ;)
It's fully functional when I'm not pulling it apart.

What I've been working on is minimizing higher frequency EMI on AC and 120VDC lines, plus limiting low frequency ripple on the 120VDC from the inverter load. With side orders of adding an AC circuit breaker, improving AC voltage regulation, and adding soft start resistor and time delay relay to the 230 to 115V step down transformer outside the shop.

High and low frequency problem solutions tend to conflict which is why many EE's think EMC is a black art.  It's not, but it sure can be a challenge.
 
I'm revising the grounding of the PV/battery bank system to tie it into the HF grounding system.  The interaction of that system with the inverter EMI/ripple seems to be a big contributor. Even a 6 gauge kludge makes a big difference.  I'll have to extend the copper flashing and add some capacitors across the load and charge shunts to "stiffen up" the ground. Once I'm finished with the EMI and ripple issues, then the PV charge regulator control circuitry will have to be revised to improve stability.  Under certain inverter load and sun-PV conditions I've seen a 6 Hz oscillation of less than 1 volt which was clearly PV charge regulator.  I haven't seen it lately so hopefully it will disappear when everything else is up to snuff.






glort

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #55 on: August 27, 2018, 10:31:46 PM »

You have certainly put a lot of development and refinement into this Bruce.
There are so many aspects to it beyond the simple voltage conversion.  Probably the reason the EMI is normally disregarded. The techs designing the inverters don't know about it and the companies paying them wouldn't want to spend the extra on R&D if they did.

BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #56 on: August 28, 2018, 12:27:39 AM »
The Magnum design EE I spoke to was very much aware of his product EMI issues and even knew where some minimal filtering would have the greatest benefit (a common mode choke on the PV input to the unit significantly improved the conducted emissions on the AC output).  He is of course not allowed to add it.  I don't think off grid inverters have to meet any emission standards.  What standards there are are to insure that radio commerce is mostly unaffected at 30 meters from the equipment...there are no standards for human health at present beyond not cooking you like a hot dog. 

I keep thinking that I'm almost finished...but I'm determined to make this as good as can be practically done.  The PV regulation mods are going to take some time; I can't just stand there and tinker with the wireless breadboard daughterboard if I have to have the inverter running to test it.  It will be a very slow process.

 I just love not having to run the Listeroid 6/1 so much.  I'm going to start looking for a 1.5 hp induction motor, 230VAC air compressor that can do 150 psi.  Then the inverter on PV power can handle daily topping off of my big 500 gallon air tank.  I'll add a processor to do available PV and load monitoring, and top off the 2200 gallon gravity feed well storage tank and air tanks as power is available.














glort

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #57 on: August 29, 2018, 02:38:18 PM »

Bruce,

I was wondering if one of these devices would be helpful in finding stray EMF radiation same as you use a transistor radio for?

https://www.ebay.com.au/itm/Wireless-FNR-Full-frequency-Detector-Radio-Wave-GSM-Laser-Lens-RF-Signal-Detect/253566993786?hash=item3b09c5457a:g:aNgAAOSwWcRa1aKb

They have a very wide frequency range and their sensitivity can be adjusted.

Specification:

Power in the 50mv-200mv detection range 30-50cm
The power in the detection range 300mv-600mv 100-200cm
The power in the detection range 800mv-1200mv 300-1000 cm

receive the frequency range: 1 MHz-6500 MHz

BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #58 on: August 29, 2018, 03:25:31 PM »
A real time spectrum analyzer (the data recording/FFT type) is the right tool for capturing peak EMI levels from low frequency events (diode noise).  Alas, these run over $8K plus a few thousand for ancillary gear.  I do have the old Spectrum Probes from Smith Designs.

The "meter" you found is a ''toy'' broad spectrum meter, which would not detect anything from my equipment.  The specifications are a farce- they mention power but then don't give power units, instead millivolts but not in units with any meaning like mv/m2.

Cornet, GHz Solutions, and Acousticom all make fairly decent, semi-calibrated broadband meters.  I have an old Aaronia and a Cornet broadband meter, but they are not sensitive enough or shielded properly for conducted EMI measurment; they would only see the highest ambient radio/microwave level across their entire range of frequencies.  They are useful tools, but not for this job.

For diode type noise (pulsed broad spectrum at ELF rate) the well chosen AM radio is actually the far more sensitive tool. 

I did get a little work done yesterday. All is well, i found the Franklin well pump QD controller diode (Triac actually) noise is fairly well controlled with a single common mode choke.  I'm considering some wiring changes for light filtering of power for the use of the well pump and future air compressor motor, with more substantial filtering of the AC distributed to the shop, since that shares the conduit with my 120 VDC line.

I've got to address the needed changes to my PV charge controller now; there is still some interaction and minor oscillation at high PV/low inverter load. The inverter load (3 mv of ripple for the well pump) is also affecting the float state circuitry- it gets kicked out to bulk charge when the inverter is running and it should stay in float.

This afternoon I should get the copper flashing to extend the HF ground over to the battery bank earth ground connection. 











BruceM

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Re: DIY Low EMF 5 step Sine Inverter
« Reply #59 on: August 31, 2018, 09:47:17 PM »
I'm pretty much done now on the inverter project.  I did just edit a short video that shows the installation in my battery bank shed.  Some minor EMI work left- I need to replace the Siemans time delay relay controller for my 240 to 115 step down transformer as it's a noisy bastard, and I have to add a box for a small common mode choke filter for the Franklin QD pump control box, which is another minor EMI source. 

https://youtu.be/U36qiYWODBk

I have more detailed videos on the design but won't put you to sleep with those.