High voltage diodes have a higher VF than the ‘ideal’ model of 0.7V, so that many of the traditional ways of checking to make sure a diode is not failed shorted, or to verify the polarity of the device, will not work with high voltage diodes.
Using a Fluke handheld multi-meter that has a diode check function, for instance, probably won’t be able to overcome the forward voltage of a diode, even at low currents. A multi-meter is providing perhaps 2.4V and some of our diodes have a rated VF of over 30V!
What will be the proposed dc power supply?current controlled power supplies capable of providing 50V or more, here proposed 100uA resolution programmable dc power supply cabling of providing 60V 3A.
How To Tell the High Voltage Diode is Good
Once you have your setup, the diode should conduct your current (100µA – 1mA, depending on how you limited the supply) in the anode-cathode direction. Reversing the current flow by flipping the diode to cathode-anode should block the current down to the leakage levels of the diode (less than 1µA). If the diode conducts in both directions, then you have a failed (shorted) diode. If current does not flow in either direction, you have a failed (open) diode.
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