A Comprehensive Guide To Understanding Your Automatic Transfer Switch, Part 2: Switch Types

A Comprehensive Guide To Understanding Your Automatic Transfer Switch, Part 2: Switch Types


As part of our ongoing effort to inform and educate our clients, Electro-Motion has created a four-part series on one of the most critical parts of your emergency backup power system: the Automatic Transfer Switch.

In Part 1, we delved into the crucial role ATS plays in ensuring uninterrupted power supply during outages. We discussed how ATS facilitates seamless transitions between the main power grid and backup generator, safeguarding critical operations.

Now, in Part 2, we’ll explore the different types of automatic transfer switches available and the most important considerations to keep in mind when choosing between them.

What Are The Two Types of Automatic Transfer Switches?

There are two types of automatic transfer switches:

1. Standard Automatic Transfer Switch (ATS):

Standard ATS is the most common type of automatic transfer switch found in backup power systems. It operates by monitoring the power status from the main utility grid and the backup generator and automatically transferring the load between the two sources during power outages.


    • Automatic Operation: Standard ATS offers fully automated operation, eliminating the need for manual intervention during power transitions.
    • Seamless Transition: It ensures a smooth and swift transition between the main power source and the backup generator, minimizing downtime for critical systems.
    • Wide Availability: Standard ATS units are widely available and come in various sizes and configurations to suit different applications.


    • Limited Bypass Capability: Standard ATS lacks the ability to bypass the transfer switch entirely, meaning that maintenance or repair work may require powering down the entire system.
    • Cost: While standard ATS units are generally more affordable compared to bypass ATS, the overall cost may vary depending on factors such as brand, capacity, and features.

2. Bypass Automatic Transfer Switch (ATS):

Bypass ATS, also known as maintenance bypass switch, offers additional functionality compared to standard ATS. In addition to automatic transfer capabilities, bypass ATS includes a built-in bypass mechanism that allows the load to be transferred directly from the main power source to the load without passing through the transfer switch.


    • Maintenance and Serviceability: Bypass ATS facilitates easier maintenance and serviceability by allowing the load to be transferred directly from the main power source to the load without interruption. This feature minimizes downtime during maintenance or repair work on the ATS itself.
    • Flexibility: Bypass ATS provides greater flexibility in managing power distribution by allowing operators to isolate the transfer switch for maintenance or troubleshooting while still providing power to the load.


    • Higher Cost: Bypass ATS typically comes at a higher cost compared to standard ATS due to the additional functionality provided by the built-in bypass mechanism.
    • Complexity: The inclusion of a bypass mechanism adds complexity to the ATS unit, requiring additional components and circuitry. This complexity may result in higher installation and maintenance costs.

How Much Does an Automatic Transfer Switch Cost?

The choice between standard and bypass ATS can have a significant impact on business continuity and operational efficiency. While standard ATS offers reliable automatic transfer capabilities at a lower cost, bypass ATS provides added flexibility and ease of maintenance, albeit at a higher upfront investment.

When considering the cost, it’s essential to weigh the potential downtime and operational disruptions associated with maintenance and serviceability. For businesses where uninterrupted power supply is critical, such as healthcare facilities, data centers, or manufacturing plants, the added functionality and reliability offered by bypass ATS may justify the higher initial investment.

What’s the difference between a Standard and a Bypass ATS?

In short, a standard ATS costs less but requires a power interruption in order to service it. A bypass ATS cost more up front, but maintenance has less impact on business continuity.

This means the choice between standard and bypass ATS depends on factors such as budget, operational requirements, and the criticality of uninterrupted power supply. By carefully evaluating these factors and understanding the pros and cons of each type of ATS, businesses can make informed decisions to ensure resilient backup power systems and maintain continuity of operations during power outages.

Stay tuned for Part 3, where we’ll delve into the type of maintenance required to keep your automatic transfer switch running and reliable. In the meantime, if you have any questions, call Electro-Motion at (650) 321-6169, or click here to arrange for a free consultation.

Comments are closed.