Magic Smoke Incident!

[ChrisOlson]

I probably need to keep it in the 2000 dollar range so I won't get perforated.

Well, that's understandable.  If the Outback on 120 volt will work fine, that's what I'd get too.  I don't know much about the Magnum Energy inverters, but I guess they're pretty good too.  The big Xantrex is best suited to installations where 120/240 volt is needed, in my opinion.  And if you don't need that, then the Outback is a better buy.

My bride was the exact opposite.  The second time the power went out in the house she about had a conniption.  She told me in no uncertain terms to go buy a "decent" inverter no matter what it costs.  When I showed her the bill she said it was less than she expected me to spend.

With either one you could do a grid-tie, so that's a new option for you if you buy a new Outback or Xantrex inverter.  The Grid-Tie fixes your dump load problems in high winds and such.  Although you still have to have a suitable dump load, or automatic turbine/solar shutdown, if the grid fails.
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Chris

[Steve Trumann]

FreeJuice

I'm glad to hear that it still has some life in it. I haven't found those exact FETs on line that is available in stock. Have you tried the (I Store) for replacement part?  After my inverter burnt up, I bought the AIMS 1500 pure sine wave. Still working fine. Not as big as I want, but money only stretches so far. Way to go!!

Steve Trumann

[freejuice]

I probably need to keep it in the 2000 dollar range so I won't get perforated.

Well, that's understandable.  If the Outback on 120 volt will work fine, that's what I'd get too.  I don't know much about the Magnum Energy inverters, but I guess they're pretty good too.  The big Xantrex is best suited to installations where 120/240 volt is needed, in my opinion.  And if you don't need that, then the Outback is a better buy.

My bride was the exact opposite.  The second time the power went out in the house she about had a conniption.  She told me in no uncertain terms to go buy a "decent" inverter no matter what it costs.  When I showed her the bill she said it was less than she expected me to spend.

With either one you could do a grid-tie, so that's a new option for you if you buy a new Outback or Xantrex inverter.  The Grid-Tie fixes your dump load problems in high winds and such.  Although you still have to have a suitable dump load, or automatic turbine/solar shutdown, if the grid fails.
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Chris

Well Chris now that you mention it, I would  like to eventually  have the capacity for 220V...all of this is part of my long term strategy towards retirement...as power keeps getting more and more  expensive, I woul like tobbe pratically independent of the grid when I do retire...that would boost the bottom line....My long term goal is to get a solar array system too....so I guess I need to also plan to grid tie too, instead of that "semi-island situation I now have. ....hummm food for thought!

 Steve I will dig a bit deeper tonigh trying to loacte those fets...thanks for the lead!....lol I can almost hear Tom snickering at my attepmt of fet replacement....i wonder if my buddy Tom has  already printed up a "I told you so...you hard head!

[dnix71]

Those FETs don't exist in stock anymore because the maker discontinued them for "new uses."

The stock number gives clues as to what it is. It's an N-channel MOSFET, the 80 is the max amps and the 25 is 250v. There were more powerful ones in the same series but they were never off-the-shelf either.

Best bet is to buy a burned out Aims just like it, or email Aims and tell them you need two off a broken unit. Aims might just have a small stash if you ask nice, or they have something that can substitute.

It would be better if you can to move one good over so you have the same number on each side and then derate your unit. It sounds like Aims was pushing the envelope in design and yours happened to fail the luck of the draw. Some military stuff isn't intended to be operated for long periods of time., just long enough to use the device or something rarely used.

As an example, one of the geiger tube sold for CDV-700's was only rated 250 hours. That's fine in a nuclear apocalypse but unsuitable for day to day use by the TSA.

[wpowokal]

Gavin "Down under" we have as many types/brands of inverters as most places but personally I prefer units made here because the Australian environment is quite harsh where people rely on their inverters.

My first was a 3Kw/9Kw surge on of these http://www.solaraustralia.com.au/solar_energy_stand_alone_inverter_everest.html When I sold the farm I left that one in service.

My second was also a 3Kw/9Kw surge one of these http://www.latronics.com.au/products/stand-alone-inverter-ls-series-2000-7000w it has slightly more surge capability than the SEA unit. I have that one with me.

My third and fourth are one of these http://www.selectronic.com.au/grid/ the grid interactive side is used to auto back up with a generator for when it's needed. They are 6/7 Kw 18Kw surge. I have only one of them now in my new system the other was sold with the farm.

If this pic works it is of the view I most use on my computer, these units can be programmed from a computer, in my case via a coms cable to the office.



My experience with inverters is that it is advisable to blow out any dust before the wet season.

Allan of the jungle

[dnix71]

http://endless-sphere.com/forums/viewtopic.php?f=14&t=7446&start=45

The Fairchild FDA69N25 is a close replacement.

eBay has better stock than Digikey

http://cgi.ebay.com/FDA69N25-250V-N-Channel-MOSFET-IC-/110616118459?pt=LH_DefaultDomain_0&hash=item19c13c04bb more than 10 available and less than $8 each.

http://cgi.ebay.com/IXTK120N25P-120N25-Polar-HT-Power-MOSFET-IC-/280530677276?pt=LH_DefaultDomain_0&hash=item4150ee6e1c This is the 120 amp version of your original Ixys part. Better than the rest also from HongKong

[frackers]

Before attempting a repair it would be well to determine what part of the circuit the blown MOSFETs are in. My guess is in the H-bridge output stage.

MSW inverters of this type have two parts:

The input side generates DC to about 130% of the nominal output voltage. This is the part of the circuit that you see repeated several times across the printed circuit board. The job of this part is to get from battery volts to the peak output volts. There are lots of sections as the input side, although low in volts is very high in amps. Usually each section is fused individually so its obvious if one section dies.

The output side (usually a bridge arrangement) converts the high DC voltage to the modified sine wave AC (no its *NOT* a square wave). This will have high voltage devices in it, with current capabilities appropriate to the rating of the inverter. When a problem occurs here it's not unusual for *ALL* the MOSFETs to go open/short circuit so I'd remove them and check them all or just replace all of them. They are usually in multiples of 4. These devices are connected directly to the load so any highly inductive load has the potential to generate large voltage spike which will kill them.

Here endeth the lesson....

[freejuice]

Frackers,
 Thanks for the for the advice! It did blow three of the four, so I will follow up with replacing at least 4!
 
Dnix71,
 Thanks for those links! I think I will get a few fets and  give it a go....what the heck huh?
 Since my inverter is still working ( still to an unknown load limit) I think I will repace the fets and retest it...if it doesnt smoke the new fets I will be surprised....if it does, I will stop right there and see if it still works again after....lol... "round two".
 If it still works, I will throw the inverter up on a shelf as a short term emergency "back up" inverter
 My larger goal is to get another inverter...probably an outback which is sealed up tight as a drum.... Outback  has a particular model which is not vented, it is derated a bit from its vented counterpart....but if humidity was the orginal culprit...I want to eliminate that vairable.
 Wow what a weekend!

[ChrisOlson]

My larger goal is to get another inverter...probably an outback which is sealed up tight as a drum.... Outback  has a particular model which is not vented

When I was looking at Outback units they had more than one.  I think they got a grid-tie model and an off-grid model for the 48 volt system.  They looked the same to me.  But I assume the off-grid one doesn't have a "sell engine" in it to sell power back to the grid.  Or maybe the grid-tie one has dual AC inputs and the off-grid only has gen input.  I don't what the deal is there, as I didn't buy one.

Personally, I wouldn't mess with that inverter you got blown.  You're using it to power an AC auxiliary load to control system voltage, right?  And you do not have emergency over-voltage auto-shutdown on your turbine, right?  The next thing you'll have blown is your battery bank when that inverter fails again.
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Chris

[freejuice]

Hi Chris,
 Thanks for the info.
 I have a dump controller which throws the excess DC voltage to a bank of resistors....Up until the inverter "popped" I was also dumping on the AC side into a smaller  water heater which was  preheating the water for my grid tied water heater.
 From the battery bank to the Inverter I  also have a DC fuse on the positive side