Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

PowerJack smoked

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Pete:
Well the powerjack blew up again. This time I was using my table saw, it was running well, then I went to restart it and it tried to start then just ran down.
The little Taiwanese lady in the inverter was telling me there were multiple faults and the inverter was beeping constantly.
Even after I turned the inverter off there was a constant alarm sound.
So I disconnected it to stop the sound.
I pulled it apart and found that it had blown the AC mosfets to bits, so I changed the boards for some spares I had on hand.
I changed the driver board with a spare too.
Then when I turned the inverter around I found that the DC mosfets were also blown.
So I changed them too.
A quick test shows that it is working again, but as it is the second time that an inductive load has killed it I am a bit wary.
I think it is time to get hold of an 8010 board for it too. I really only want an inverter not all the other stuff such as a charger etc.
So I will install it tomorrow and see how it goes, hope it lasts until a more simple replacement board arrives.
Pete

lighthunter:
Hi Pete,
 
I feel your pain. I too have a few failed inverters in my past.

Most of the time if not all of the time, there is a reason when mosfets perish.  Usually the failure happens because of one of two things. 1... Load current exceeds specification in some way.
Load current sometimes just happens as part of life. Short circuit... like in my case, relay contact failure.
Or
2)  Wrong sizing of filter components. Poida did all the legwork of figuring this out. Warpspeed contributed imensely as well, take a look at this thread if you havent already done. Resonant frequency can be a killer of the best bridges (road bridge) tacoma narrows, let alone an inverter mosfet bridge.

https://www.thebackshed.com/forum/ViewTopic_mobile.php?FID=4&TID=9409&PID=122471&LastEntry=#122471

I certainly dont know all the answers and im not suggesting you need to invest much time in it. If there is evidence of an unexplained problem though, it can be worth it to make a change to the choke or cap to see if things improve. From reading threads it appears like some have had transformer/choke sizing that continued to eat mosfets regardless of the inverter boards until changes were made. I do think there is a solution that will make it indestructable for normal use.

Glad u got her running again!

Pete:
Thanks for the reply LH , I will look up the post you mentioned.
I have ordered a 24 volt 5000 watt board to have on hand if it becomes smoke again.
I am thinking it has to do with starting current , but as both saws I was using were universal motors it seems odd that the starting current was high enough to kill it.
I have my 500 Farad capacitors now and will charge them and fit them in the next few days. Hopefully that will help with starting currents and voltage dips.
Cheers
Pete

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