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Systems & Data Center · Intermediate

Automatic Transfer Switch (ATS)

A switch that automatically transfers electrical load from a failed utility source to a backup source such as a generator.

Definition

Facility ATS units move building load to generators after a utility outage, while rack-level ATS units let single-corded equipment draw from either of two feeds.

Example

When utility power fails, the ATS transfers load to the generator once it reaches stable voltage and frequency.

Exam tip

Use a rack ATS to provide feed redundancy for devices with only one power supply.

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