Frequency-changing with mercury-arc mutators

This paper deals with the existing systems for the conversion of 3-phase 50-cycle alternating current, to single-phase at 16¿ cycles, with mercury-arc-mutators. Frequency-changing with mercury-arc mutators may be performed either with a direct-coupling mutator convertor or with a mutator convertor with intermediate direct voltage. The direct-coupling mutator convertor is characterized by the method of producing the single-phase voltage curve, which is built up from sections of individual 3-phase voltage curves; this method involves direct coupling of primary and secondary networks. The mutator convertor with intermediate direct voltage consists of a rectifier and an invertor having a d.c. circuit as intermediate element between the a.c. networks. No type of existing mutator convertor is perfect in itself. The future development of mutator convertors for traction purposes depends largely upon the demand for frequency-changing.