How Do Automatic Transfer Switches Work With Generators?

When the power goes out, having a generator is one thing—but having it kick in automatically? That’s where an Automatic Transfer Switch (ATS) becomes your best friend. In simple terms, it’s the device that ensures your power supply moves seamlessly from the main grid to your backup generator and back again, without you lifting a finger.

Let’s explore how automatic transfer switches work with generators, why they’re useful, and how to choose the right setup for your home or business.

What Is an Automatic Transfer Switch?

An automatic transfer switch is an electrical device that monitors your mains power and automatically switches to generator power if the main power supply fails. Once power is restored, it automatically switches you back to the grid.

Think of it as the brain behind your backup power system. It knows when there’s a blackout, starts your generator, and safely switches the power source—all in a matter of seconds.

Key Benefits of Using an ATS:

• No manual work required during an outage
• Improved safety by preventing back-feeding into the grid
• Faster power restoration
• Ideal for critical loads like medical equipment, refrigeration, and security systems

How Does an Automatic Transfer Switch Work?

Here’s a step-by-step look at how an ATS functions with your generator:

1. Constant Monitoring
   The ATS constantly checks your incoming mains power for any disruptions.
2. Detecting an Outage
   When it senses a power failure or voltage drop, the ATS sends a signal to start the generator.
3. Switching Power Sources
   After the generator reaches the correct operating voltage, the ATS safely disconnects your home or business from the grid and connects it to the generator.
4. Power Restoration
   Once mains power is restored and stable, the ATS automatically switches back to grid power and shuts off the generator.
5. System Reset
   Everything resets and returns to standby mode, ready for the next outage.

Where Are Automatic Transfer Switches Used?

ATS units are commonly used in places where consistent power is essential:

• Homes: For households that want peace of mind during storms or outages
• Businesses: For retail, offices, and hospitality where downtime means lost revenue
• Healthcare: Hospitals and aged care facilities rely heavily on ATS setups
• Farms and Remote Properties: Where power reliability is often a challenge

Types of Automatic Transfer Switches

Choosing the right ATS depends on your generator size, load requirements, and whether you need full or partial power coverage.

1. Open Transition ATS (Break-Before-Make)

This is the most common type and works by momentarily disconnecting power before switching sources. It’s reliable and cost-effective but causes a brief interruption (typically less than a second).

2. Closed Transition ATS (Make-Before-Break)

Used in critical applications, this switch connects the generator before disconnecting mains power, avoiding any power loss. It’s more complex and often used in hospitals or large businesses.

3. Service Entrance Rated ATS

This combines the main circuit breaker and ATS in one unit—handy for residential or small commercial properties where space and simplicity matter.

Key Considerations Before Installing an ATS

Before getting an ATS installed, here are a few things to keep in mind:

• Generator Compatibility: Ensure your ATS is compatible with the type and size of your generator.
• Load Requirements: Do you want to back up the whole house or just key circuits?
• Professional Installation: Always have your ATS installed by a licensed electrician to ensure safety and compliance with Australian standards.

Do You Need an ATS for Your Generator?

While manual transfer switches do exist (and cost less), they require someone to be on-site and ready to switch power sources manually. That’s not always ideal—especially during a blackout, storm, or when you’re away.

An ATS is the smart choice if:

• You want an uninterrupted power supply.
• You’re protecting critical systems like fridges, medical devices, or computers.
• You want peace of mind knowing your generator will automatically kick in during any outage.

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