I need to have a rectifier setup capable of up to 400A, the voltage will be from 7-75v (higher voltage will have much lower amperage, max power will be about 7200 watts) and the power will not be run for extended periods, maybe a few minutes at a time, with at least equal amount of off time. This setup will be used for various things from welding, electrolysis, resistance heating and a few more things.
I found some rectifiers on ebay that have me a little puzzled as I looked at their voltage & current rating and compared them to surface area and volume, and pricing was a little odd as well.
What I found odd is the volume of the 300A vs the 400A, as it is larger than the 400A and the 60A, 100A, 150A are all the same size. The 200A is also larger in volume. None of these units have a heat sink but have a smooth metal back on which I thought I would place a computer CPU heat sink. I was really surprised by the price of the 50A units, as they cost about 17% of what a 400A unit would cost. IDK if running 8 of these in parallel would work I don't intend to use them for this high amperage project but will order them for some others.
Now if the size of the rectifier makes any difference, I guess the main thing would be heat handling, then placing a CPU heat sink should be sufficient, but I'm thinking that using 2 200A units in parallel along with 2 heat sinks, might be a better option as it has more "cooling" capacity? It would also be possible to use 4 100's and not worry about a fan on the heat sinks, less moving parts, but more connections for rectifiers.
All of these units are from the same manufacturer and look basically the same, so I assume they will have virtually identical forward voltage loss, though it isn't stated for all of them, at least all of the same amperage should be the same.
I found some rectifiers on ebay that have me a little puzzled as I looked at their voltage & current rating and compared them to surface area and volume, and pricing was a little odd as well.
Code:
Voltage amp Cm^2 In^2 Cm^3 In^3 Price $ / amp
1600v 400 74.8 11.59 254.32 15.52 $29.00 $0.073
1600v 300 73.7 11.42 294.8 17.99 $28.00 $0.093
1600v 200 71.25 11.04 285 17.39 $21.00 $0.105
1600v 150 31.2 4.84 109.2 6.66 $8.60 $0.057
1600v 100 31.2 4.84 109.2 6.66 $8.60 $0.086
1600v 60 31.2 4.84 109.2 6.66 $8.40 $0.140
1000v 50 9 1.395 10.08 0.615 $7.89 $0.016 10 pcs
Now if the size of the rectifier makes any difference, I guess the main thing would be heat handling, then placing a CPU heat sink should be sufficient, but I'm thinking that using 2 200A units in parallel along with 2 heat sinks, might be a better option as it has more "cooling" capacity? It would also be possible to use 4 100's and not worry about a fan on the heat sinks, less moving parts, but more connections for rectifiers.
All of these units are from the same manufacturer and look basically the same, so I assume they will have virtually identical forward voltage loss, though it isn't stated for all of them, at least all of the same amperage should be the same.