In through the out door on SW2512's

Was putting in an autotransfer switch to island (during blackouts) an up and running stacked SW2512 system when things got out of hand.
Had the DC breakers disconnected, AC1 grid breakers disconnected, AC2 generator disconnected, and AC out Load disconnected. Got confused on those old generator bypass Square D disconnects and put hot AC into Inverter 1 load out for about 5 seconds. :cry:
Manual says "worst thing you can do". Yup. Now have stacking error and neither inverter will synch to AC1 grid in.
Xantrex in British Columbia says " at least the FET board is most likely smoked, maybe the control board s/w is smoked as well". Got the cover off and am searching for the FET board on the DC side, haven't figured out if it's a daughter board or the DC backplane board. Any help?

The only visible damage I see is a large black lead to the small transformer, insulation is cracked and cooked.

These inverter only have 2 years of runtime from new in box, and mostly just float charging. Only inverted about a dozen times, used to work perfectly.

I haven't tried factory reset (desperation) and I haven't tried inverting since the incident. Just trying to synch to AC1. Even with stacking cable removed, still no synch, just blink, on both inverters.

Probably stupid to hope that just because every other breaker was open, including AC out to load on inverter 2, that there was no path for the current to chase through but I'd like to at least eyeball some obviously smoked components to know which boards need attention.

Any words of wisdom or derision here?

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: In through the out door on SW2512's

    Does not sound good...

    The FETs will probably look something like this:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: In through the out door on SW2512's

    they might not look like that after blowing.:roll:
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: In through the out door on SW2512's

    I fear it's time to accept that the milk has been spilled, and start over :cry:
  • System2
    System2 Posts: 6,290 admin
    Re: In through the out door on SW2512's

    Sometimes you get real lucky...

    After reading every Trace SW post on this board and poring over the 4048 power schematic somebody so graciously posted in the past, I went back on site to do more fault isolation.

    I had only given the guts a 5 minute stare previously before reaching conclusions, so with better light, sunset into the power shed, more time and financial motivation, I wasn't able to see any fried components on any board. And the presumed bad wire just had some dried weirdness impersonating cracks but the insulation was actually fine and undamaged. So with no AC in or out, I lit up the DC side and put both units into invert mode (no load connected) which I had seen a post here. Both units acted fine and inverted with no codes.

    The schematic showed a 35A circuit breaker inline between the transformers and hot out, found it hiding on the side of the case that was buried up against the shed wall. (Tiny shed, need mirror on a stick just to cable up the a/c side with face smashed against the plywood wall...you've been there before...). Pried it out from behind with a screwdriver and sure enough it needed a reset.

    Remove stacking cable, light up AC1 in hot, set invert on, and it synched! Oh Yeah!
    Shove a stubby screwdriver into lower unit breaker, same deal, needed reset. Then it synched too. No errors so far, but no 240 yet.

    Put the stacking cable on backwards, was rewarded with stack error. Flipped it around and the error cleared. Lit up hot again and both legs synched, no errors, no financial loss, no more suicidal thoughts, Oorah!

    Now I'm back working on the damnedest custom distributed autotransfer switch (of my own design) spanning several hundred feet of service panels. This site is an active farm with the power system feeding several buildings up to an acre apart, well, and irrigation pumps. There's only 1 grid/meter input at the road with all the buildings coming off a centrally located service panel in a star configuration. The campus runs off the grid and batteries charge from both grid and solar. This job started with the campus load side doing double duty as the charging/grid AC1 in, with circuit breakers making and breaking the loop. Either charge only, or invert only, manually controlled by confused humans.

    So I trenched 6-3 from the meter directly to AC1 in (shortest copper run possible) and put real big contactors between inverter and AC1 in, AC load out to campus, and a humongus 300 amp contactor between meter and campus. The contactors that "see" grid power have 240v coils, so that a grid blackout instantly islands the campus mechanically. The load contactor is controlled by a tiny 24v dc Click PLC. The PLC senses grid up or down through 240v relay at the meter, senses load hot or cold via a relay, and ensures the loop is broken by further disconnecting both grid contactors, then connects load contactor. When the grid comes back, the PLC will sense it, wait for 5 minutes on inverter for the power lines to quit blowing in the wind, disconnect load, and then permits reconnect to grid by allowing the big contactors to fire.

    It's not instant, but it beats the long walk to the road, then to power shed, and the necessary manual button pushing on the inverters. The inverters will now just remain in search mode since it can only see a load when the PLC fires that contactor. Next step will be time of day metering, peak hours on battery, recharge at night from grid, gotta crunch some numbers on rate plans to sort out the specifics on that plan.
    Cheers and thanks for the advice.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: In through the out door on SW2512's
    87octane wrote: »
    When the grid comes back, the PLC will sense it, wait for 5 minutes on inverter for the power lines to quit blowing in the wind, disconnect load, and then permits reconnect to grid by allowing the big contactors to fire. .....

    What keeps your spinning motors from shedding copper coils, when the phase glitches, switching back to grid ? (or does the SW sync to grid ?)
    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 ,

  • System2
    System2 Posts: 6,290 admin
    Re: In through the out door on SW2512's

    The only motors are always submersed water pumps and the transfer time is long enough that they stop spinning completely. Excellent question though. I was worried about the freezers as well, used the "ear and stopwatch test". The good thing is, it's a farm, not a data center, don't have to beat that 100ms number.