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ANels.2
ANels.2
Visitor II
August 8, 2020
Question

FERD20L60C, Using this product in a simple 3ph rectifier and find that the diodes show conduction in both directions using a commercial quality DMM, but only in one direction using a higher quality meter, why?

  • August 8, 2020
  • 1 reply
  • 537 views

FERD20L60C, Using this product in a simple 3ph rectifier and find that the diodes show conduction in both directions using a commercial quality DMM, Behave as one would expect using a higher quality meter, why?

Using two inexpensive, but not junk DMMs, the diodes showing about 1 order of magnitude more voltage drop in reverse bias (but still conducting), both vales are not those in the data sheet. I can accept that these diodes have different construction, but I am not sure why this is upsetting a lower quality DMM so much. I find it a off-putting. None of the documentation makes mention of this. Could somebody help me out here?

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1 reply

Peter BENSCH
Peter BENSCH
ST Technical Moderator
August 11, 2020

If you did a diode measurement while checking using the DMM, then this would just give an estimation if the diode behaves as such.

To do a real check of FERD diodes you should use test conditions as mentioned in the datasheet, e.g. measuring the forward voltage drop at a forward current of 5 or 10 amps.

Good luck!

/Peter

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