Design of reactances and transformers which carry direct current

D. C. Prince: The first question that came into my mind was, what is the real measure of these reactances? The reasoning that I went through is something like this: if we have a certain small variable current that is produced by a ripple voltage in the case of a rectifier or by whatever the alternating impulse is, and then we have a steady direct current that must be carried, the function of the reactor is to keep the ratio of the incremental current, the variable current to the direct current, as small as possible.