Help, RFI woes

Hello,

I have an AIMS 1000 watt inverter, hooked up to a stand alone deep cycle battery. Its ran with 2' of el cheapo 4awg wire. I receive a large amount of RFI. My test equipment will not function when connected to the inverter. I have read about ferrite chokes, twisted pairs and shielding. I will be trying the chokes and twisted pair options soon. I must get this inverter working with little to no RFI. How would I go about testing for RFI?
How do I know if its on the DC cables, the AC lines, or from the inverter its self? I will be trying out an AM radio to try and deduce the source of the RFI.

I have tried a triplite power strip with filtering, and a triplite Line conditioner. So far only the power strip has helped.
Can anyone help me further diagnose and reduce the RFI? Also, what is the best method for testing, measuring and tracking the sources of RFI in an inverter system?


ANY input is GREATLY APPRECIATED.


Thanks in advance.

Brad

Comments

  • mike95490mike95490 Solar Expert Posts: 9,571 ✭✭✭✭✭
    Re: Help, RFI woes

    Is the inverter pure sine wave or mod sine?

    Does it have a FCC class B cert sticker on it ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Help, RFI woes
    mike90045 wrote: »
    Is the inverter pure sine wave or mod sine?

    Does it have a FCC class B cert sticker on it ?

    Thanks for the speedy reply Mike. 8)

    The inverter is advertised as a "pure sine wave" inverter. Which played a big part in its selection.

    I cant say about the FCC sticker. But after doing some reading, I will definitely check.

    The inverter is at my shop at the moment. I will be checking it in the morning.
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: Help, RFI woes

    You might wish to read through this thread:

    Radio Noise from PV System


    This was about Solar Charge Controllers--But much of the DC side of the inverter would be the same issues. The AC side tends to be an easier fix (or at least, not the problems of DC).

    Do you know what frequency ranges are causing problems? Is it conducted or radiated noise that is causing you problems (or common mode AC, etc.)?

    You might try calling NAWS (our host) and see if they have any information about a "quiet" inverter.

    It is sad, but many solar mfg. choose not to bother with FCC emissions requirements.

    You may end up getting a few different brands/models and testing them for your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Help, RFI woes
    BB. wrote: »
    You might wish to read through this thread:

    Radio Noise from PV System


    This was about Solar Charge Controllers--But much of the DC side of the inverter would be the same issues. The AC side tends to be an easier fix (or at least, not the problems of DC).

    Do you know what frequency ranges are causing problems? Is it conducted or radiated noise that is causing you problems (or common mode AC, etc.)?

    You might try calling NAWS (our host) and see if they have any information about a "quiet" inverter.

    It is sad, but many solar mfg. choose not to bother with FCC emissions requirements.

    You may end up getting a few different brands/models and testing them for your needs.

    -Bill


    Thanks Bill. I honestly do not know yet where the noise is coming from. I do not know how to truly test for the origin or the frequency of the noise. (hoping the linked thread will point me in the right testing direction. Just need time to read :(...) I figure I need a way to test and measure the "noise" before I can try methods to solve it.

    The inverter, packaging, and manual make no reference to any FCC requirements. But I did notice that in the manual, it states that the inverter is shielded and any problems that are encountered with EMI/RFI are basically the purchasers problem. The inverter is "golden"

    The model number/part number is PWRI100012s.

    I tested the AC voltage and frequency and got 120v @ 59.7hz Both under load and at idle... if that helps any.
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: Help, RFI woes

    You can try things like a 50'-100' extension cord and put the battery/inverter away from your equipment (place the battery/inverter/ac cable on the ground--don't put on a table, string wire in air). If you still are having problems--then most likely the issue is the AC wave form itself. (In the 30-180 MHz range, cables over ~10 feet do not carry that much energy to the destination).

    If that is the case (you still have problems), then I believe that the AC wave form is just not clean enough for your usage (have you looked at the AC wave form to verify that it is somewhat sine wave?).

    If the problems go away, then there is some hope that you can filter/limit the emissions from the inverter + wiring.

    What is your test equipment measuring? Audio, RF emissions, etc.? What are the problems (audio / rf emissions swamping what you are trying to measure, microprocessors rebooting, random readings on power meters, etc.)?
    • Setup equipment in "back yard".
    • Run from 120 VAC grid power and get your equipment working properly, then turn on inverter without connecting AC cord.
    • Try inverter next to test equipment and far from test equipment (but not powering your stuff). Equipment still work?
    • Run inverter AC cord near your equipment but don't connect--still work?
    • Wrap a couple turns of AC line cord around your equipment--still work?
    • Put a load on the inverter AC cord (not your test equipment)--still work? etc...
    • Power your equipment from AC Inverter--now fails?
    -Bill

    PS: If you can use a 300 watt (600 watt surge) 12 volt TSW inverter--The MorningStar unit is not too expensive and quite a few people use it off grid that have HAM/AM/FM radios here. I have not hear of any complaints yet.

    If you are serious hurting to get your equipment working, I would give it a try.

    AIM, at least their larger inverters, seem to be a bit on the "inexpensive side" and I would not be confident that they are what they claim to be at times...

    Perhaps the off-grid HAMs/DIX'ers here can make some brand/model suggestions...
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • loreleclorelec Solar Expert Posts: 200 ✭✭
    Re: Help, RFI woes
    95ImpySS wrote: »
    ... My test equipment will not function when connected to the inverter.

    What kind of test equipment, and how is it malfunctioning?

    If it's true sine, I doubt there's anything on the AC line that would cause issues. Do you have the inverter located at a distance from the affected equipment?

    BTW, I use an Exceltech inverter with my equipment, and haven't noticed any problems. Bill might be right on...a different brand might be in order, at least to troubleshoot with.

    Marc
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: Help, RFI woes

    Per Marc's recommendation--Some Exeltech Sine Wave Inverters are available from our host. And their website is:

    www.exeltech.com

    -Bill

    PS: I should add--that AM band interference is actually a very common complaint with solar equipment of many brands (including "good ones")--If your system measurement is in the "low frequency range" of AM radio band (for example)--then your only solution is usually distance between the inverter and the load. Low frequency RF radio emissions are difficult to solve and the antenna effect is usually not very efficient. Equipment that is close by might be coupling more from a capacitive coupling than by magnetic coupling. Moving the test equipment by 50' from the source might be your best bet.

    But I am with Marc in that AC RF noise on the power line might not be your problem--otherwise things like florescent lamps in your lab (i.e., arc type lamps) could be causing lots of problems.

    If your equipment is having purely "functional problems"--then it might be the not-good-enough AC sine wave.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,571 ✭✭✭✭✭
    Re: Help, RFI woes
    BB. wrote: »
    ...
    PS: If you can use a 300 watt (600 watt surge) 12 volt TSW inverter--The MorningStar unit is not too expensive and quite a few people use it off grid that have HAM/AM/FM radios here. I have not hear of any complaints yet......

    Isn't it class B rated too ??
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BajaGringoBajaGringo Solar Expert Posts: 40 ✭✭
    Re: Help, RFI woes

    Any chance this could be a grounding issue???
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: Help, RFI woes

    No--there is nothing on the MorningStar website about any FCC rating for their inverter. A few of their solar charge controllers are FCC B rated. I did a Google "FCC" search on the Exeltech website and did not find any results.

    Grounding in terms of shielded equipment (sheet metal box, seams, etc.) and shielded cables can help (again, depending on frequency--typically 30MHz to 180 MHz for cables, and 100MHz to over 1-2 GHz for chassis slot antenna, etc.).

    However, running a ground rod and tying that to the inverter/test equipment--pretty much useless. We did that for testing to try and get a "repeatable" ground plane for measuring equipment for FCC regulations. But I had never seen any reduction in output.

    A best, if you have a "door" or moving panel on an electronic device--then grounding with a very short flat braided cable (1/2" or wider--depending on length/frequency) can help (with both emissions and electrostatic discharges too).

    -Bill

    PS: If you have lots of "extra cabling" in your setup--wrap it in figure "8" (eights) instead of circular... Figure 8's do not have common mode/antenna coupling effects. Circular coils of cables are very nice antenna. Can make a big difference in some cases.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: Help, RFI woes

    The only FCC Class B certified inverter I know of is the Xantrex XW-6048 series
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,138 ✭✭✭✭✭
    Re: Help, RFI woes
    The only FCC Class B certified inverter I know of is the Xantrex XW-6048 series

    And also the xw4024 and xw4048

    SG did you see the post about backfeeding an xw with an inverter based (generator)? Sounds scary but would it charge it's battery? Reliably? More than once?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • System2System2 Posts: 6,290 admin
    Re: Help, RFI woes

    Wow, thanks everyone! Keep the info coming :D

    Heres the low down.

    These inverters are installed in mid 90's Chevy vans. They are used by a local telecom company. I do not know what exactly they test for in their boxes but it has so far been isolated to the inverter/AC power cable from the inverter. They use a laptop hooked up to the equipment, which tests something in the telecom boxes (hundreds of wires, I will know more soon). We can have the laptop charger plugged into the inverter and then try to run tests. The attempted tests will always throw an error message. As soon as we switch to the laptops battery power or city electric power, everything works a ok, every time they run a test. The van/inverter is about 15-20 feet away connected by a single plane Jane extension cord.

    The inverter is in the back of the van, attached to a tool rack with stainless 5/32's bolts. The inverter is connected to a 12v deep cycle battery underneath the inverter about 2' away with 2' 4 awg battery cables. Copper ring terminals on each end, crimped, soldered and heat shrinked. The battery is connected to a 200 amp ANL fuse (15' 4 awg run), then to a 160 amp Napa battery isolater (mounted behind the seat) by a 4" 4awg battery cable. (all terminals are crimped, soldered and heat shrinked...) The Isolater is then connected to the alternator and the vans starting battery under the hood.

    The deep cycle battery is grounded to the side of the van by a 1' cable and a 3/8 bolt. Paint removed at binding point. Inverter is grounded to the batteries negative terminal. I have noticed there is a grounding point on the inverters face plate. It has not been connected. I will soon be trying most if not all of the above solutions/tests as soon as I can. Everyones input is greatly appreciated. I hope the above info answers some of your questions. Until I can get one of these vans back into the shop, I cannot do any troubleshooting.

    Thanks again!
  • BB.BB. Super Moderators, Administrators Posts: 32,609 admin
    Re: Help, RFI woes

    Sounds like common mode noise in the AC line circulating through the laptop into the test gear (RS 232 connections are a classic for ground loops).

    You could try an AC 120 VAC isolation transformer between the inverter and the laptop. May or may not work.

    Depending on what the actual Laptop to Test gear communications link is (RS 232, RS 485, Ethernet, etc.)--you can find optical isolators for many communications standards to throw into the laptop to test gear communications link.

    Another thing to look at... Your 12 VDC is grounded in the van... Many TSW inverters will accept a grounded neutral (or may even have a grounded neutral connection inside the inverter)... So, grounding/floating the inverter output may help. But be very careful--many MSW inverters will let out the magic smoke when both 12 VDC and 120 VAC "Neutral" are both connected to the same conductor/ground (dead short right across the inverter's output transistors).

    If the only Inverter powered device is the laptop--Other than a short life on the AC adapter--I cannot imagine what would cause the laptop to have problems--they will run on almost any power or the internal battery--so nothing should be coming into the laptop and causing it problems.

    Some computer power bricks have a grounded AC plug, and some don't. Check with a ohm meter for electrical connection between the AC plug ground and the RS-232 or other Metal case ground on the laptop.

    There are DC laptop converters that you can try too.

    Yep--the more I think about it--the more the problem is probably related to the communications link between the computer and the test gear... "breaking" the ground noise/signal noise link between the computer and test gear is the right solution (isolating communications link, isolating the inverter ground).

    You could try the Morningstar inverter--It is 12 volts, very efficient, and its output is isolated from the battery bank.

    Perhaps even keeping two inverters--one powering the test gear and a second for powering the laptop would be a quick solution.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Help, RFI woes

    If the RFI is radiated, then the likely source is the battery cabling. The currents there are huge and are can really transmit. Keep them short, twisted if possible, add capacitors to both ends.
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