1) monopolar d.c. link
2) monopolar DC link
a link having only one energised pole whatever the means of return of the direct current (d.cVDC)
GRM: n. (1,2)
USG: both DC and d.c. are accepted abbreviations for direct current
References:
SEE bipolar d.c. link
SEE bipolar DC link

ENERGY TERM COURTESY OF ENERGY.EU