A metal rectifier is an early teep o semiconductor rectifier in which the semiconductor is capper oxide or selenium. Thay war uised in power applications tae convert alternatin current tae direct current in devices sic as radios an battery chairgers. Westinghouse Electric wis a major manufacturer o thir rectifiers syne the late 1920s, unner the tred name Westector (nou uised as a tred name for an overcurrent trip device bi Westinghouse Nuclear).
In some countries the term "metal rectifier" is applee'd tae aw sic devices; in others the term "metal rectifier" normally refers tae copper-oxide types, an "selenium rectifier" tae selenium-airn types.
Metal rectifiers hae nou been replaced bi silicon diodes.