I have a question about an electronic rectifier diode component.?

on a good part, If you measure the resistance, on low range, in the forward direction it will measure a low resistance. In the other direction it will be a VERY HIGH resistance. Use fixed range not auto ranging.

Yes.

With an operating power rating of (3 amps)*(400V) = 1.2 kW you need not worry about damaging the diode with excessive current from doing a forward and reverse resistance check with an Ohmmeter.

All diodes are necessarily polarized as far as direction of operating current is concerned. Also the Ohmmeter that you use must have the capability of furnishing in excess of .75 Volts across diodes junction in order to check the diode's resistance in the forward direction.

Most meters have a diode scale. Silicon diodes have forward voltage threshold of about 0.7Volts. Compare the reading in one direction to the other direction. But if the diode is connected to low resistance parts on both sides, it is very difficult to separate the diode from the rest of the circuit unless you disconnect one end. Perhaps fortunately, semiconductors usually fail as a dead short or open, so if what you measure is not a dead short, it's probably OK.

This is a very ordinary rectifier diode. Use a multimeter on a non-autoranging low ohms scale, measure it's resistance both ways round, one way should be an open circuit and the other way round it should be a fairly low resistance. Cannot give you exact values as it depends very much on the design of your multimeter.

Many digital multimeters have a range on the ohms scale specifically to test diodes. If not, then just use the lowest range as suggested by Philomel. Low resistance in one direction, high resistance in the other.

use a volt/ohmmeter

set it to ohms

the diode should have low resistance in one direction and infinite resistance in the other..