mercury arc rectifier

mercury arc rectifier (plural mercury arc rectifiers)

1. (electrical engineering) A rectifier which converts alternating current to direct current, using a cathode tube with a pool of liquid mercury. Now superseded by solid-state rectifiers.
   • 1961 March, “Interim report on the Glasgow suburban electric train failures”, in Trains Illustrated, page 175:

     The secondary winding is laid in four coils, one on top of the other, with oil passages round the laminated-steel core; its 2,770V a.c. output is converted to 1,970V d.c. by four air-cooled mercury arc rectifiers, which feed each pair of 975V traction motors through a smoothing choke.

• “mercury arc rectifier” in Lexico, Dictionary.com; Oxford University Press.