Automatic Transfer Switches (ATS) are electrical devices that automatically transfer power from a primary source (usually the utility) to a backup source (such as a generator or UPS) when it detects a power failure – and switches back once utility power is restored.
It ensures uninterrupted power supply to critical loads without requiring manual intervention.
How an Automatic Transfer Switch Works
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Normal Operation: Utility power is available → ATS connects load to the utility.
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Power Failure: ATS detects utility power loss or voltage/frequency deviation.
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Backup Activation: ATS signals generator (or UPS) to start.
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Transfer: Once backup source stabilizes, ATS switches the load to it.
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Return to Normal: When utility power returns and stabilizes, ATS reverts load back to utility.
Why Use an ATS?
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Ensures continuity of power to essential systems
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Automatic operation during outages or power quality issues
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Avoids downtime for critical operations (e.g., medical, IT, security)
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Supports generator startup and load transfer without human input
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Complies with safety and code requirements (NEC, NFPA 110, etc.)
Common Applications
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Hospitals
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Data Centers
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Industrial facilities
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Telecom sites
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Commercial buildings
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Fire alarm and emergency lighting systems
Key Features to Consider When Selecting an ATS
| Feature | Consideration |
|---|---|
| Amperage Rating | Match load size (e.g., 100 A to 4000 A+) |
| Voltage | Match system voltage (e.g., 208V, 480V, 600V) |
| Number of Poles | 2, 3, or 4-pole depending on grounding system |
| Transfer Time | Fast enough for your load type |
| Source Sensing | Monitors voltage, frequency, phase, etc. |
| Communication | Remote monitoring and control (e.g., via BMS or SCADA) |
| Enclosure Type | NEMA rating for indoor/outdoor use |
| Manual Bypass Capability | For maintenance with no load interruption |
IBPS Repairs/Tests all brands of Automatic Transfer Switches. In addition to Repairs IBPS represents the GE line of ATS Switches through our sister company Atlantic Controls. This line-up is available from 40A through 4000A as well. Contact us today to find out more.