Alright class, let’s dive into one of the most critical components of backup power systems: the automatic transfer switch, or ATS. Think of it as the brain behind your facility’s emergency power system. Its job? To automatically switch your facility’s power source from the utility grid to your backup generator when there’s an outage—and back again when power is restored.
What Does an Automatic Transfer Switch (ATS) Do?
In simple terms, an ATS is like a traffic cop for electricity. When the utility power is flowing normally, the ATS directs it to your facility without a hitch. But if the grid fails (say, due to a storm or a blackout), the ATS instantly senses the problem. Here’s what happens next:
- Detection: The ATS immediately detects the power loss. Within milliseconds, it kicks into action and sends a signal to start the backup generator.
- Transfer: Once the generator reaches the correct voltage and frequency, the ATS switches the power load from the utility to the generator. Now, your facility is running on backup power.
- Re-Transfer: When the utility power is restored and stable, the ATS reverses the process. It transfers the load back to the utility and signals the generator to shut down.
- Testing and Monitoring: Many ATS models can run automatic tests to ensure everything is working correctly. They also monitor power quality, checking for things like voltage drops or surges.
Steve Saari, Duthie Power Generator Technician, further explains in the video above, “When normal power, or utility comes back online there is a time delay preventing the generator from switching back – just in case normal power is unstable for a while (usually 10 minutes is a good number).”
Types of Automatic Transfer Switches
There are a few different types of ATS setups, and which one you use depends on your facility’s needs:
- Open Transition ATS: This is the most common type. It briefly disconnects power before switching from one source to another. There’s a tiny gap—usually just a fraction of a second—when your facility isn’t powered, but it’s barely noticeable.
- Closed Transition ATS: For facilities where even the slightest power blip could cause problems, closed transition switches offer a seamless transfer. There’s no break in power because the ATS overlaps the utility and generator power sources during the switch.
- Soft Load ATS: This type gradually shifts the load between power sources to avoid sudden changes that could stress your electrical systems.
- Bypass Isolation ATS: This is a specialized type that allows maintenance on the ATS without interrupting power. It’s common in hospitals and other critical facilities where power reliability is paramount.
Why is the ATS Important for Facility Managers?
Understanding how your ATS works isn’t just a technical detail—it’s essential for ensuring your facility stays operational when the lights go out. A malfunctioning ATS can leave your facility in the dark, even if your generator is in perfect shape. Knowing the ins and outs of your ATS also helps you troubleshoot issues, manage maintenance, and make informed decisions about upgrades or replacements.
Key Maintenance Points
- Regular Testing: Schedule routine tests to make sure the ATS responds quickly and correctly to power outages.
- Load Bank Testing: Use load bank testing to simulate a real power loss, ensuring the ATS works under actual conditions.
- Visual Inspections: Look for signs of wear, corrosion, or loose connections in the ATS, especially in older systems.
Final Thoughts
The ATS might not be the most glamorous piece of equipment in your facility, but it’s absolutely essential for keeping your operations running smoothly. As a facility manager, your job is to ensure that this device is properly maintained and tested, so it can do its job when you need it most. When an outage happens, you want the ATS to be ready to spring into action, making that seamless switch from utility power to generator power with no drama—just smooth, uninterrupted operations.
ATS Class dismissed!
For more information on how a transfer switch works – request a service quote or give us a call at 1-800-899-3931.
