AC Transformer failure Trace SW4024

stmarstmar Posts: 274Solar Expert ✭✭
I have had two AC transformers fail over  the last 15 years in my Trace/Xantrex SW4024 and I would like some opinions or theories as to why this happened. I realize things don't last forever but want to see if anything we do is contributing to the issue. First time grid was down for 3 days, we used power for heat and refrigeration sparingly. When the grid came up everything looked fine, inverter went to bulk to charge batteries. Then after a few minutes the fans came on and a fire erupted from the transformer, luckily I was there and shut it down quickly. Second time, just last week, grid was down for for several hours but the wife did not realize it and did her normal morning routine, hair dryer and curling iron, so used quite a bit of power. When we found the grid down we cut power usage and battery bank came back up to about 25 volts. After about a 12 hour outage the grid came back up, inverter went into bulk charge as normal then after a few minutes the fans came on and the coil smoked. I got to it before it burst into flames and shut everything down. Anybody have any ideas as to why this would happen? We have had grid outages in the several hours range many times and everything came back up normally. Could the excessive use of power been a factor? Hair dryer, curling iron, etc. this time and heat and refrigeration for days in the first scenario.

Comments

  • mcgivormcgivor Posts: 2,044Solar Expert ✭✭✭✭
    Hair dryer, curling iron are resistive loads, no power factor involved, anything with an indication motor or microwave is a different story, imbalance could be the cause on a split phase, hard to determine over cyber space, but the more I think of it, split phase results in more problems than it solves. Others may differ.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • mike95490mike95490 Posts: 7,786Solar Expert ✭✭✭✭
    My guess is a software glitch having to do with power restoration.   Internal limits are supposed to prevent that, but sometimes a "race condition" causes issues.   The SW line is mature enough, I'd expect these issues to be solved, unless your 2nd unit was a 15 year old spare with old software in it.
     My guess is the transformers were fine till some software glitch cooked them.  Mr Dave Angelini  ought to be able to chime in with his view

    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 ||
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  • EstragonEstragon Posts: 2,594Registered Users ✭✭✭✭
    I have a heat gun that seems to use some sort of rapid pulsing to adjust temp. At some mid-range heat levels, the thing makes lights go all disco on me. My inverters seem to be okay with it so far...

    I wonder if in your case when the power came back on it might not have been quite kosher for a spell. For example if lots of folks "upsteam" between you and the grid were running loads after the outage, and you're also drawing a lot for battery charging, the AC may have been browning out some. Browning out can be hard on loads and may have contributed to the failures?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Dave AngeliniDave Angelini Posts: 3,882Solar Expert ✭✭✭✭
    mike95490 said:
    My guess is a software glitch having to do with power restoration.   Internal limits are supposed to prevent that, but sometimes a "race condition" causes issues.   The SW line is mature enough, I'd expect these issues to be solved, unless your 2nd unit was a 15 year old spare with old software in it.
     My guess is the transformers were fine till some software glitch cooked them.  Mr Dave Angelini  ought to be able to chime in with his view

    At Mr. status, I am honored! Could be software but I doubt it. Most of many people using the old SW's this very day are not connected in any way to the grid. The grid is the source of surges and also grid owners doing dumb things under battery charging/loads. No SPD's

    Offgrid it is the use of gensets and again dumb things under load. Arc welding etc. In either case SPD's not being used.

    An offgrid home with no genset and minimal lightning, has a power system and appliances that seem to last forever, in my opinion.


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • stmarstmar Posts: 274Solar Expert ✭✭
    I would go along with grid quality in both cases, long widespread outages. When we do have an outage I minimize power consumption while the inverter is charging in bulk mode. That is not to say that the freezer and refrigerator don't run during that time. With the new SW I have a Xfer switch for grid and inverter so I will have more control if we do have an extended outage, I can wait a reasonable amount of time for the grid to stabilize then let the batteries charge with no load or I can even let the batteries charge from solar array with no load on the inverter.
    I am afraid to ask but what does SPD stand for?
  • EstragonEstragon Posts: 2,594Registered Users ✭✭✭✭
    In context, SPD = Surge Protection Device.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • westbranchwestbranch Posts: 5,083Solar Expert ✭✭✭✭
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • stmarstmar Posts: 274Solar Expert ✭✭
    edited July 17 #9
    I have two older Sq D SDSA1175 surge suppressors. Is there any way to test these to see if they are good? These do not have an indicator light. If not I will buy a new one.

    Went ahead and ordered a new surge suppressor just to make sure. Is there any place/application where I can use the old SDSA1175's? Do you have to use a breaker with them? If so I really don't know any place in my system where they would work.
  • BB.BB. Posts: 27,682Super Moderators admin
    Here is the Schneider website for these devices:

    https://www.schneider-electric.us/en/product/SDSA1175/load-center-1ph-secondary-surge-arrestor/?range=61965-type-sdsa1175&node=209917816-sds

    They say there should be a green LED on them. LED=On is protected. LED=Off is no protection.

    Looking around, they are fused MOV devices (metal oxide varistor), and they should be installed close to the output/branch circuit side of the fuse (surge=>MOV clamps voltage=>causes high current through breaker=>trips breaker == As I understand the function). So, yes, you need a breaker (Rated for the branch circuit wiring).

    No breaker (such as AC Mains from transformer), and more than likely the excess current will simply blow the fuses (and possibly the MOV themselves) and not effectively protect downstream equipment.

    If the output (AC power supplying device) has limited output current (smaller genset, smaller AC inverter), then you would not need to add any additional breakers/fuses to the system (In my humble opinion).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • stmarstmar Posts: 274Solar Expert ✭✭
    "They say there should be a green LED on them. LED=On is protected. LED=Off is no protection."

    Not on these, they are probably 20 years old, before LEDs. No indicators of any kind that I could find, I was wondering if there was a way to test with a meter? To be safe I went ahead and ordered a new unit.

  • BB.BB. Posts: 27,682Super Moderators admin
    You could test (possibly) with a capacitance meter.... If there were blown fuses or other MOV problems, the capacitance would probably read lower (do a resistance check too--Look for higher than normal leakage current).

    If a MOV is damaged--They can be blown apart (normal operation during a surge event):


    Here is a thread where MOVs and lightning suppression was discussed:

    http://forum.solar-electric.com/discussion/12968/metal-oxide-varistors-mounted-in-pv-junction-box

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Posts: 5,083Solar Expert ✭✭✭✭
    edited July 17 #13
    you might want to watch the SPD comparison video and read the second link on LIGHTNING..

     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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