The best thing to do ( I do anyway) is to protect the input with say 120amps of breaker... standard 240v ones will do. ( yes it is DC and it is high current I know that too) The 240v ones are typically $4.00 on ebay. They are not all the same, some weld shut on startup, most perform perfectly well. I use noark ones, they seem to run fine on <60vdc... DO NOT USE ON >60v DC though. I use 2 x 68amp ones on my inverters and battery strings for that matter.
EDIT: Further to the above. Clockman had a discussion with breaker manufacturers in Europe. They agreed that <60v, the 240vac ones are fine to use, but derate them 20%... thats it.
A big problem is the start current ( to charge the caps from cold at first turn on) This is in the order of over 400 amps, and is why ANY breaker will have a good excuse to weld up on start up splat. For some reason, most of the 240v ones seem to handle this ok, the noark ones from ebay do it with ease, and Ihave yet to see any untoward effects. Some of the other ones I have used... not so good. If you just splat the cable to the input bolts, you will so substantial damage to the lug or bolt threads... it is a big big surge..... especially on the 6 cap boards.
It is best to have a resistive charge up system, but my particular design will hang if the start up voltage rises too slowly, and requires a reset switch in the design. I think the PJ suffers this slow cap charging ok. Even a push button with 40 ohms in series to charge the caps will solve it all.
End Edit.
This protection may/may not stop fet destruction ( generally not)... but it will protect your circuit boards.
I do/did a lot of experimenting on these PJ and my own designs, and I don't care if the fets go bang, but I hate the burnt resistors, burnt totem trannies, and subsequent board damage. It is stupid and unnecessary.
So input fuses will stop the cascading noises you normally hear on failure. It is just breaker goes, and the drivers and the rest of it survives, and you generally only need to replace the fets.... and they won;t have blown the pads away either.
.......oztules...... expert destroyer of fets and other tender electronic components.
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