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My question concerns a future research project in electrocoagulation (water treatment) I am planning right now.

I will have a lab power supply connected to two (or more) plates in water. The operation will run in a galvanostatic mode, meaning I want to have a constant current through the system as one of the major outcome determining factor is the charge density through the plates (e.g. \$mA/cm^2\$). The plan is to procure a lab power supply that can supply up to 30 A, since that is at the higher end of the range I want to test. My measuring probes and the power supply will be programmable, meaning I have the possibility of centrally controlling the electrical inputs and the data collection of experiments from my computer.

One thing that I want to test is reversing the polarity of my electrodes to counteract electrode passivization, i.e. switching the anode and cathode during the experiment. I would like to do this in a programmable fashion as well. For example, either at timed intervals or maybe when a certain voltage drop has occurred due to the increased resistance from the passivization.

Given that I have all required signals connected to the computer, what would be the way to solve my problem? The programmable side will not be an issue for me, I am mostly interested in the best way to solve the problem.

Requirements:

  • Switching circuit should be able to handle up to 30A passing through the switching side.
  • Programable

Thanks in advance!

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1 Answer 1

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Use a H bridge / motor controller (where your anode and cathode replace the motor).

enter image description here

Image source: multiple motor h bridge?

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  • \$\begingroup\$ Would it work interchangeably? A DC motor would be an inductive load and the between the electrodes in my circuit it would be a resistive load. I've searched around a bit, have not found an H bridge/ motor controller board that can handler higher currents yet. Also searching around for high current DPDT programmable switches, but I can't find any of the shelf products. \$\endgroup\$
    – Aquapuer
    Commented Nov 29, 2019 at 10:33
  • \$\begingroup\$ No, not interchangeably, but one way: if it can switch a inductive load, it can also switch a resistive load. But not necessarily the other way around \$\endgroup\$
    – Huisman
    Commented Nov 29, 2019 at 10:52
  • \$\begingroup\$ @Aquapuer Searching internet for "30A brushed motor controller" yielded e.g.: robotshop.com/en/medium-power-motor-controllers.html or nl.rs-online.com/web/c/automation-control-gear/… (nl.rs-online.com/web/p/dc-motor-controllers/7736844). These are suggestions how to search, I didn't go into details if it fits your application. \$\endgroup\$
    – Huisman
    Commented Nov 29, 2019 at 10:56
  • \$\begingroup\$ Ok, thank you. I think you've pointed me in the right direction. \$\endgroup\$
    – Aquapuer
    Commented Nov 29, 2019 at 12:54

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