power supply vs relay

power supply

noun
  • That part of a piece of electronic apparatus that provides appropriate voltages for the rest of the electronics from the connected AC source. 

  • A source of power such as the mains or a generator. 

  • Used other than figuratively or idiomatically: see power, supply. 

relay

noun
  • An electrical actuator that allows a relatively small electrical voltage or current to control a larger voltage or current. 

  • A track and field discipline where runners take turns in carrying a baton from start to finish. Most common events are 4x100 meter and 4x400 meter competitions. 

  • A series of vehicles travelling in sequence. 

  • A new set of horses kept along a specific route so that they can replace animals that are tired. 

  • A new set of hounds. 

  • A new set of anything. 

verb
  • To pass on or transfer (information). 

How often have the words power supply and relay occurred in a corpus of books? (source: Google Ngram Viewer )