Trace SW5548 putting out 166v AC

AntonAnton Registered Users Posts: 6
What's up? I have three SW5548s and they are all putting out high voltage to some degree. The voltage follows the control board when I swap them between inverters. I tried replacing the precision voltage reference, but that did not fix it. A friend who knows electronics has been helping me figure it out, I am out of my depth here, but if anyone has some hint, maybe we can figure it out. I am ordering a control board to use to fix one of them, and to help diagnose, I'll see what happens.

Is this something they do after a time? I couldn't find any threads on this particular problem on the forum anywhere, but maybe I missed it?

Thanks,

Anton

Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    welcome to the forum.
    although i am not that familiar with these inverters i have to ask what voltage it is that you are seeing that has you alarmed? (note to self again-look at the thread title:cry:) out of curiosity, did you shut down the inverters for a spell to measure what voltage the utility is showing (assuming you are grid tied)?
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Trace SW5548 putting out 166v AC
    Anton wrote: »
    What's up? I have three SW5548s and they are all putting out high voltage to some degree. The voltage follows the control board when I swap them between inverters. I tried replacing the precision voltage reference, but that did not fix it. A friend who knows electronics has been helping me figure it out, I am out of my depth here, but if anyone has some hint, maybe we can figure it out. I am ordering a control board to use to fix one of them, and to help diagnose, I'll see what happens.

    Is this something they do after a time? I couldn't find any threads on this particular problem on the forum anywhere, but maybe I missed it?

    Thanks,

    Anton
    Do you have a lot of voltage drop in your AC conductors from your inverter? Voltage drop manifests itself as voltage rise when the current goes the other way, as from an inverter to a service.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Trace SW5548 putting out 166v AC
    niel wrote: »
    welcome to the forum.
    although i am not that familiar with these inverters i have to ask what voltage it is that you are seeing that has you alarmed? (note to self again-look at the thread title:cry:) out of curiosity, did you shut down the inverters for a spell to measure what voltage the utility is showing (assuming you are grid tied)?
    If his problem is voltage drop/rise in his AC conductors, measuring the line voltage with the inverters off won't show the problem.
  • AntonAnton Registered Users Posts: 6
    Re: Trace SW5548 putting out 166v AC
    niel wrote: »
    welcome to the forum.
    although i am not that familiar with these inverters i have to ask what voltage it is that you are seeing that has you alarmed? (note to self again-look at the thread title:cry:) out of curiosity, did you shut down the inverters for a spell to measure what voltage the utility is showing (assuming you are grid tied)?

    They are SW5548s, which are capable of grid tie, but I am using them off grid. They are within 2' of the batteries, and testing is being done within 2' of the inverter, thus I think there is no line loss worth considering.

    Of the three I have, one is putting out 133vac, one is putting out 142vac, and one is putting out 166vac. I had been using the 133v one, and it worked fine, but when I tried one of the others, is felt funny so I tested it. Since all of them are putting out high voltage, I suspect they all have the same problem. I bought them used as a batch, so I don't know their history.

    I have tested the 133v one and the 142v one with no load, and with varying loads from 700w to 2500w and there is no sag in voltage. I am afraid to test the 166v one under load, as I don't have a load that I don't care to fry.

    WHen I take the control board from one and put into another one, the high voltage follows the control board to whichever invergter I install it in. I can buy a new control board for $1100, but would like to see if there is anyone here who has done component level repairs on the boards.

    THanks!
  • AntonAnton Registered Users Posts: 6
    Re: Trace SW5548 putting out 166v AC

    Also, I am slightly concerned that if I buy a new board that there is something in one of the other components that will cause the same problem in the new board.

    Anton
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    yes, it sounds like something went amiss in the boards, but i'm not familiar enough with the inverters to know if another cause elsewhere in the inverter can lead to this. they are old and outdated inverters and you take a chance with them. it's a roll of the dice whether to get new boards or new inverters. maybe try 1 new board to test the waters for awhile and if good then investing in the boards for the other 2 is feasible. i don't know if there may also be a voltage adjustment within the board so after getting a working new one you can then explore the possibilities on a bad board as the bad board is junk otherwise anyway.
  • boBboB Solar Expert Posts: 965 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    It may be a broken wire on the AC feedback transformer which, I think, is on the relay board ? Those little transformers have "hair wire" and can
    break off to the pins that they are soldered down with.

    No AC feedback voltage means the output voltage would go high... Very possibly to 166 volts RMS.

    You can give this a try if you have a DC power supply... Run the inverter off of the power supply and
    turn its voltage up and down. If that AC voltage goes up and down with the DC power supply voltage,
    that transformer might just be the problem.

    If you try that with a known good inverter, the AC output voltage should stay relatively constant with
    a change in DC input voltage.

    boB
  • AntonAnton Registered Users Posts: 6
    Re: Trace SW5548 putting out 166v AC

    When I move the control board to a different inverter, the voltage goes with the inverter. When I move the AC board to a different inverter, the voltage does NOT go with the AC board.

    Also, as I say, two of them are at 130v and 140v, so if that wire being broken would send it to top voltage, why the difference between them? Maybe I should check resistance on those transformers to see if they are all the same.

    But thank you for the response, I will do that test and see what I get, what I have done so far may not be conclusive.

    Anton
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    by boB's description it sounds as if at least the 166vac inverter might have the transformer issue. not sure of the other 2.

    boB,
    do you know of a voltage adjustment to try on the other 2?
  • AntonAnton Registered Users Posts: 6
    Re: Trace SW5548 putting out 166v AC

    I just talked to someone on the phone today who tells me there is a jumper on the control board that will adjust the voltage. He didn't say how much it would adjust it, nor did I get how that works. I don't know if there is a way to make the range larger.

    If I knew how the circuit works, and what was wrong with the circuit, I would be able to assess whether adjusting it with a resistor change somewhere would be a good fix or a band aid. I have a couple of tests to do, apparently if a few FETs are out, it will cause there to be more area under the RMS curve. I have to borrow a neighbor's scope and see if I can see a waveform problem. I will also do the DC input variation if I can figure out how to rig up a variable DC source.

    Thanks,
    Anton
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    sounds good. keep us informed.
  • boBboB Solar Expert Posts: 965 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC
    Anton wrote: »
    When I move the control board to a different inverter, the voltage goes with the inverter. When I move the AC board to a different inverter, the voltage does NOT go with the AC board.


    Do you mean here that the 166 volts does not stay with the AC board ? i.e. The AC board does not appear to be the culprit ?

    If so, and I am remembering that the AC sense transformer is on that AC board, then it won't be the AC voltage sense transformer.

    And do you mean that when you move the control board from the 166V inverter that the inverter you put that control board
    in does go to 166 volts also ?

    I don't remember any jumpers adjusting the AC output voltage but maybe jumpers adjust the DC voltage reading ??
    I thought the SW used AC feedback for voltage adjustment but maybe it was feed-forward from the DC input voltage ?

    It's been a very long time since I've had my nose in an SW inverter.

    boB
  • AntonAnton Registered Users Posts: 6
    Re: Trace SW5548 putting out 166v AC

    Yes, the high output does NOT go with the AC board, and DOES go with the control board, so yes, I am of the opinion that the problem does not lie with the AC board.

    I have been told by someone who should know, that the inverter does rely on AC feedback to control output, and that the transformers that you are talking about can cause high output.

    The jumper messes with the DC side of the voltage sensing, I think, but am not sure. There is a precision voltage reference on the board that I replaced to no avail, it is putting out high voltage, and in fact higher voltage on the higher AC output control board, if you follow. Control board (CB) 1 puts out 130v in whichever inverter it is installed in, CB2 puts out 140v in whatever inverter it is installed in, and CB3 puts out 166v in whatever inverter it is installed in. CB1 has 10.2vdc at the precision dc voltage reference (PDVR), CB2 has about 10.2 also, but CB3 has 10.6vdc there. Replacing the PDVR did not fix it. Not sure what other circuitry controls it, but I will take look at the traces with the jumper in mind, thinking that there might be some resistors there that could be changed out to adjust voltage output, or more importantly, checked for accuracy to find out why it is doing this.

    I will mention that I have located a source for control boards and will buy one to install it and see what happens.

    Anton
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    Hi Anton,

    I have nothing specific to offer.
    There have been several links to schematics appear on this Fourm in months/years past You may have searched this site, and have seen this, . ... did a bit of poking around, and found some chatter in the following thread:

    http://forum.solar-electric.com/showthread.php?18513-SW-5548-Mosfet-Replacement&highlight=5548

    Some posters in that Thread may have docs for diagrams beyond the FET board.

    If time permits, will look a bit more. Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • boBboB Solar Expert Posts: 965 ✭✭✭✭
    Re: Trace SW5548 putting out 166v AC

    Aside from any voltage references, there might be a simple resistor that has changed value giving the wrong feedback.

    You might be able to compare some suspect resistors from one board to another while disconnected from the AC and power board.
  • jiggawattjiggawatt Registered Users Posts: 2
    I have a sw5548 putting out 160-170v at 54hz and making a bad noise. Possibly same problem i have replaced the fet board to no avail. Did you ever find a solution Anton?
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