First post here. Found this place while looking for a solution to my problem. My background is Navy trained electronic tech. (FC to be precise) So an engineer I'm not, but I do fix the stuff. Anyway, at work, I have a 3 phase full wave rectifier with a capacitor ripple filter. Here's a very basic, and badly modified, stolen schematic from wikipedia of it. http://www.rjsoap.com/work/rectifier.jpg [Broken] They're actually SCR's and a firing board for it, along with all kinds of monitoring circuits, bleed down resistor for the filter cap when the powers turned off, etc... but I'm taking it down to the basics. The rectifier output is rated at 28.5vdc, 600amp continuous with 2000 amp peak. The capacitor filter is actually an 8 capacitor bank in parallel, 50v 100000uF each, so in my book that's a .8F cap sitting there. Ripple voltage is 1.8v p-p Before I get to the problem, I want to preface this with all readings are nominal. Output Vdc is 28.5, ripple voltage is 1.8v p-p. The problem is, the physical wires that connect the capacitor bank to the bus bars on the rectifier are getting very hot. My thought is the wires are too small. They are 6 awg. We put a 300 amp load on the rectifier and ran it for 5 minutes or so. We took the temp of the wire, and it's sitting around 220 degrees f. I then put a clamp meter on the wire, and it's reading around 280-290 amps AC with a 300 amp load on the rectifier. Way too much for a 6 gauge, I know. If I put a 2000 amp load on it, the wire reads about 400 amps. Now, here's the deal. The "engineer" thinks something is wrong with one of the SCR's in the rectifier OR something's wrong with one of the caps to pull that much current. My thought on a failed scr is, if something was wrong with one of the SCR's I would never get 28.5 vdc out. I've had these fail shorted before, and that's a spectacular fail! I've also had them fail open, and that's a boring failure, but it would never reach 28.5vdc out. I've had caps fail shorted, that's a spectacular fail too. Although I've never had large caps like these fail. I'd imagine the little white pressure relief plug would come flying out. If one failed open, no big deal, but I think the ripple voltage might be a little higher. (Could be wrong on that one.) And if the capacitance in one is going down, I'd never know, because today I realized out of all the meters we have to measure capacitance, we don't have one that can measure that high. So I ordered a new one... Should be in next week. Anyway, I'm sticking with my "The wire is too small theory" as all other readings are nominal, and with all the other monitoring circuits, if something was off it would shut down. The reason I mentioned the temperature of the wire is the engineer says he ran a 600 amp load on the prototype rectifier for 12 hours straight, and he didn't fry the wire. I asked him if he physically touched the wire to see if it was hot, and he didn't. I looked up the insulation rating for that wire and it's rated for 200 degrees f. Which tells me, and I can't prove it so this is just a guess on my part, but it probably would need to be around 400-500 degrees before the insulation would start melting. We have a new rectifier that should be coming off the line tomorrow or Friday, which I will be looking at to settle this matter. But was wondering if anyone had any other thoughts on this. Thanks!