24 Hour Emergency Power Services • Call 608-661-9910

Close Menu

When A Flywheel UPS Makes Sense

By now we have examined flywheel UPS machines from several different angles: their history, how they work, and how to properly maintain them. We also need to examine the most obvious question: What considerations go into making sure a flywheel UPS actually makes sense for your business? Today we will examine some things to consider when looking to purchase a UPS system.


When evaluating for a flywheel UPS, you should start by reviewing the environment you want to install it in. Is the environment dirty, dusty, or caustic? While a flywheel can be used in a harsher environment than VRLA batteries might be able to handle, a dirty environment can affect performance. Some flywheel designs may still have electronic components that are susceptible to environmental conditions. Also, be sure to look at the size of environment you want to install the UPS in. Flywheel UPS can be designed to fit in small environments, so this may work better if space is at a premium.  In any location, ensuring that the unit is installed to specification, and allows for ease of service, is important.

Run time Requirements

A Flywheel will typically provide a very short run-time compared to a traditional battery system, generally measured in seconds, rather than minutes. This is because the inertia of the flywheel is what is generating power. Prior to installation of a flywheel, it’s important to consider your risk tolerance for a shortened run-time. If you have a generator, what is the typical time required for the generator to start and transition the load? If you live in a cold or harsh climate, it may take a bit longer for your generator to start and transfer loads. If a flywheel UPS still makes sense, but you need longer run time, there are hybrid options for flywheel systems, allowing a client to pair both the reliability of a flywheel with the run-time of a VRLA battery. Talk to your service provider to see what might make sense for your application.

Economies of Scale

There are economies of scale to be aware of when purchasing a flywheel UPS. You typically see a better return on investment (ROI) on machines that provide a higher amount of power. The smallest flywheel UPS units are typically about 200 to 300 kW, and they are more often seen in environments at 500kW to 750kW and higher.

Costs- Flywheel UPS Versus VRLA Battery UPS

It is always important to consider Total Cost of Ownership (TCO) for the purchase of any UPS unit. The greatest TCO on flywheel UPS is seen if you are only using the flywheel UPS as a stand-alone machine and it is coupled with batteries. In this case, you only need to replace bearings on the system per manufacturer recommendation. However, you do need to watch out for hidden costs in maintenance.  A flywheel UPS may need fewer maintenance items during its life-cycle, but because there is sometimes a smaller pool of experts that are qualified to work on flywheel UPS machines, they can be harder to find outside of major metro areas, so their services typically cost more. Average cost to of a service contract to support a Flywheel UPS is often higher than a traditional battery solution.

Regulatory Issues

Thankfully, there are not too many regulatory issues to deal with when installing a flywheel UPS. However, you will want to pay attention to a flywheel UPS’ seismic rating if you are installing your UPS in an area affected by seismic zones. Because these machines are sensitive to oscillation, if they are in an active seismic area, they may not be the best choice so be sure to discuss this point with your sales engineer.

DRUPS (Diesel Rotary UPS)

What about Diesel Rotary UPS units that have a flywheel? Adding a DRUPS flywheel to a facility or structure can be difficult if a customer already has their core infrastructure established. In general, this is a good option if extended run-time is needed, or in a facility that needs conditioned power throughout the entire infrastructure. You are essentially installing a power plant on your property in this case, with a UPS configured into it. This type of set-up can work well for airports, data centers and hospital, any facility that has a large consumption of clean, conditioned power.

The best candidates for flywheel UPS units are typically companies that are large power consumers that need conditioned power or that have “dirty” or utility power that needs to be “cleaned,” and that are in major metro areas, so they have access to highly trained technicians. Quality Power Systems can go into more depth with you individually about whether a flywheel UPS is right for your environment. Contact us today and see how we can help you make a decision that makes the most sense for you.

Take a deep dive into how Flywheel Uninterruptible Power supplies work—read our series of articles about Flywheel UPS.

Components-of-a-Successful-IT-Data-Center When A Flywheel UPS Makes Sense

By now we have examined flywheel UPS machines from several different angles: their history , how…

Maintenance on a flywheel ups Flywheel Maintenance- A Checklist

In our previous articles, we discussed an overview of Flywheel UPS systems and the types of…

cylindrical flywheel comparison Types of Flywheels- A Comparison

Recently, we discussed the history and basic workings of the Flywheel UPS system , but did…

Is a Flywheel UPS right for your organization? Get in touch with the experts at QPS to find out more.

This field is for validation purposes and should be left unchanged.