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backup relay

noun

Definition of backup relay 

: a secondary relay to protect a power system against faults in the event of failure of the primary relay to function as desired

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First Known Use of backup relay

1950, in the meaning defined above

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Dictionary Entries near backup relay

back up

backup

backup light

backup relay

backup signal

backveld

back vent

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Time Traveler for backup relay

The first known use of backup relay was in 1950

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