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?

[ANels.2]

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?

[Peter BENSCH]

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