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I have some components, I believe they are transistors, that I got from a decommissioned electric train. They are rather large, but have no markings on them other than what is on the diode in the center position DSA 42-16A 436C which isn't pulling anything up for me.

Is there anything I can do to test it for it's load capacity? I was thinking of using it in a PWM for a 480V 200HP motor and wasn't sure how many I would need to run in parallel. This was located near the regenerative braking circuitry for what it is worth.

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    \$\begingroup\$ Are you sure they're transistors? I clearly see a diode -|>|- marking on the can to the right. \$\endgroup\$
    – Richard the Spacecat
    Commented May 16, 2018 at 22:34

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Found some info here, it seems to be a DSA series avalanche type diode:

http://pdf.datasheet.live/cdf8de06/abb.com/DS42-11A.pdf page 3

DSA 42-16A 436C seems to stand for:

  • DSA - avalanche type
  • 42A rated
  • -11 1100V

And the 436C could be just a datecode? No idea so far.

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  • \$\begingroup\$ Awesome Richard, that tells us info about the diode that is screwed to the top. I had been nervous to unscrew it before, but I did now and found it to be just an aluminum heatsink. \$\endgroup\$
    – Alan
    Commented May 16, 2018 at 22:44
  • \$\begingroup\$ Yeah, that's just a big heatsink. I don't think it has anything else in it, the diode (as is fairly common for power diodes) has a fairly large forward voltage. That times the large current demands a fair bit of power to be dissipated. In this case the specced Vf is 1.7V, rated current 42A, giving us about 70W to be dissipated somehow. A heatsink of just about that size with airflow sounds like a good idea. :) \$\endgroup\$
    – Richard the Spacecat
    Commented May 16, 2018 at 22:48
  • \$\begingroup\$ Oops, looking at the datasheet again, it seems to be 100A rated max RMS, 60A mean forward currentm 800A peak one cycle surge. Although the type code desc suggests otherwise. Weird, but okay. Still, a really beefy diode. \$\endgroup\$
    – Richard the Spacecat
    Commented May 16, 2018 at 23:08

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