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I’m looking to build my own high current full bridge rectifier to power electrowinning cells.

I need a DC supply that is adjustable 0 - 5 V, and could supply up to ~50 kA (50 kiloamps.) Obviously this isn’t an off-the-shelf supply, which is why I’d need to construct one myself.

What types of diodes can I use that can handle the extreme currents?

What class of capacitors are capable of handling the high discharge current?

I’ve heard of silicon-controlled rectifiers being used in such applications, which I assume are thyristors. Could anyone give any detail as to why thyristors would be used instead of just regular diodes?

I need some form of surge protection, would spark gaps do the job? Recommendations please.

NOTE: Sorry for the long list of questions, as I do not want to spam the forum with a million different questions on specific problems of a very specific application.

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  • \$\begingroup\$ something of this magnitude needs the capacitance and low ESR of a battery bank with at least a 3 phase alternator to charge the battery \$\endgroup\$
    – D.A.S.
    Commented Feb 12, 2020 at 1:24
  • \$\begingroup\$ You probably need to figure out how to use many smaller supplies rather than one that large. You nee thyristors to make the voltage adjustable. \$\endgroup\$
    – user80875
    Commented Feb 12, 2020 at 3:01
  • \$\begingroup\$ Ok, from a little research, it looks like a common method is to use large inter digital cathodes at 300 to 400 amps each with a couple per cell. Then you add more cells. Getting 5V at 300 amps is much much easier than trying to do it with a single 5V at 50,000A supply! I've got two 13.8V @ 45A in which the output voltages are variable(used to power amplifiers), 6 or 7 of those and you've got 5V at 300A. Look at power supplies for Amateur Radio. \$\endgroup\$
    – GB - AE7OO
    Commented Feb 12, 2020 at 3:28

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A silicon-controlled rectifier (SCR) is a type of thyristor. Another type of thyristors is the Gate turn-off thyristor (GTO).

A diode base rectifier is called an uncontrolled rectifier. With the use of SCRs (among other devices) you get a controlled rectifier. The benefits of a controlled rectifier is that you can control the load voltage and power factor. Thyristor rectifiers are the most common solution for this kind of application (electrowinning).

If you want to stay with diodes, then you're looking at devices like these ones. In the case of thyristors, then these ones.

Regarding capacitors, you would need to design your own capacitor bank.

By the way, 5V at 50 kA means 250 kW, for this kind of power one normally has to take into consideration the generation of harmonics and reactive power consumption, since utilities normally impose penalties for harmonics and reactive power consumption above certain limits. You might want to look at 12-pulse rectifiers.

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