Mercury-arc rectifiers in the coal-mining industry

ALTHOUGH mercury-arc rectifiers at present constitute only a small part of the total installed capacity of a-c to d-c conversion equipment in coal mines, in the past three years 21 rectifiers of a total rated capacity of 8,100 kw have been placed in service in 15 coal mines. Considered alone, this would not be important, but, since these rectifiers exceed in number of units and capacity other forms of new conversion equipment installed in the same period, a definite trend toward the use of rectifiers is indicated. It is the purpose of this paper to discuss the causes for this trend and to record, in so far as it is possible, the results which have been obtained with rectifiers in mining service.