Drysdale ac polar potentiometer

Drysdale ac polar potentiometer

[′drīz‚dāl ¦ā¦sē ¦pō·lər pə‚ten·chē′äm·əd·ər]
(engineering)
A potentiometer for measuring alternating-current voltages in which the voltage is applied across a slide-wire supplied with current by a phase-shifting transformer; this current is measured by an ammeter and brought into phase with the unknown voltage by adjustment of the transformer rotor, and the unknown voltage is measured by observation of the slide-wire setting for a null indication of a vibration galvanometer.