Does A UPS System Work With A Backup Generator?

Does A UPS System Work With A Backup Generator?

by Isaac Prakash January 23, 2023

Is a lone UPS system enough to safeguard your business from the impacts of a potential power outage? While a UPS can certainly provide excellent protection against power surges and other technical problems that could otherwise damage your electrical equipment, what happens if a power outage goes on for longer than anticipated? Would a back-up generator be a viable addition to your emergency power supply plan? And will a UPS system work with a back-up generator? In this article, we’ll tell you everything you need to know…

How do I configure generator and UPS system compatibility?

While it is definitely worth investing in an uninterrupted power supply system and a back-up generator, there are a number of important considerations that often go overlooked. For example, ensuring that both systems complement one another and function properly. 

You must make sure that both your UPS and generators are compatible and perfectly synchronized. Given how many different options there are on the market today, finding the right UPS system and back-up generator that align can feel overwhelming. 

Fortunately, we’ve got a few pointers that can help you make the right decision and avoid any potential UPS compatibility issues.  

  • Check voltage and frequency: all UPS systems run on a particular voltage range. While these vary from one UPS device to another, they all have a certain cut-off point. Generators on the other hand are far more flexible in voltage and frequency with a wider range than the average UPS. As such, if the voltage and frequency of the generator is outside the UPS system’s limits, the UPS will reject it as a power source. 

  • The UPS type is critical: another critical aspect in ensuring compatibility between UPS and back-up generator is the UPS’ type. 

    • For example, a standby and line-interactive UPS draw power from their batteries to balance the variations in frequency. If you have a generator that has an unstable or incompatible frequency, the UPS system may switch between power sources, ultimately reducing the battery power, requiring further maintenance, and in some cases interrupting the power supply completely (which can be very problematic). 

    • Other UPS types however—like double-conversion units—can filter the various frequencies during regular operations thus reducing the likelihood of battery drain and power drops (which in turn reduces the need for avoidable UPS repairs / replacement batteries). 

    • Fuel source: the fuel source of your generator is also an important consideration when configuring your UPS generator system set-up. For example, diesel generators can burn for longer than most other generator types, which can be critical to ensuring that power supply is kept steady in the event of an emergency. 

    Does the size of the generator matter?

    Contrary to what you may have been told, size does matter. However, it’s not as simple or straight-forward as you may have hoped. 

    When it comes to the proper sizing of your generators, you must make sure that the generator sizes exceed the UPS’ power rating. Your generators must support the power rating, with an excess of at least 20% to 30% to cover power line conditioning. 

    When choosing the appropriate sizing for a generator to assist your UPS system, you must consider the following factors: 

    • Make a list of all electrical equipment relying on back-up power.
    • Consider how each piece of equipment would impact your business if they were to fail. For example, what would have the biggest impact on your profits and reputation? (e.g., server room / data centres) Conversely, which equipment could affect the health & safety of your employees should they fail? 
    • Identify which electrical equipment doesn’t need UPS support. Are there any items that can remain non-operational during a power outage without impacting your business?

    Asking the above questions can help you determine precisely how much power you need from your UPS – and thus how to size your back-up generator accordingly. 

    More questions about UPS systems & Back-up generators

    Let’s tackle some of the most frequently asked questions surrounding UPS / generator systems: 

    Is a UPS system a generator? / UPS generator meaning

    While you may have heard the term UPS generator before, its meaning is different to what you might expect. 

    Even though generators and UPS systems are both designed to serve as back-up power systems in the event of a power outage, a UPS system is not a generator. 

    It’s important to recognise the distinction between the two (and how well they can complement one another). 

    • Back-up generators are intended to be used as a temporary source of power during outages and other environmental / weather incidents that may result in an electrical surge and / or loss of power. 
    • UPS systems are designed to protect your electrical equipment against power surges and outages, whilst keeping the equipment running without interruption until the mains powers up again.  
    • The major difference between a UPS and back-up generator however, is the fact that UPS systems only have the capacity to provide a few minutes of power. These critical minutes are intended to offer enough time to either power down properly or switch to an alternate power source. 
    • A back-up generator will take time to power up. This means that if used without a UPS system, your electrical equipment will power down in between. 
    • A UPS system can ‘bridge the gap’, between the initial power outage and the time it takes for the back-up generator to power up and feed your electrical equipment accordingly. 

    Does a generator affect the UPS?

    A generator can negatively impact a UPS system if they aren’t compatible. As mentioned above, if the voltage and frequency are out of sync, the UPS will likely reject the generator as a power source. Additionally, if the wrong type of UPS is being used with a particular generator, it can lead to all-manner of complications. 

    That said, if you take the necessary precautions to avoid any unnecessary UPS generator compatibility issues, they can complement each other wonderfully. 

    Is a back-up generator worth it?

    Having a back-up generator provides a number of advantages – for large corporations, small to medium-sized businesses, and at home. As to whether a UPS system is enough without the support of a back-up generator depends on a number of factors. 

    A UPS system on its own is critical for preventing equipment from shutting off abruptly or shorting out due to an electrical surge. However, it can only provide a very limited amount of power. While this can provide you with plenty of time to power down your equipment appropriately, without an alternate power source you will not be able to continue your operations until the power returns. Depending on the circumstances, this could be a matter of minutes, hours or longer. 

    If you have a back-up generator in place however, no matter the circumstances, you can keep your equipment powered up sufficiently without impacting your productivity. 

    The same applies for a home office environment. Having a UPS is great for temporary outages, but if you find yourself without power for several hours, you’ll wish you had a UPS generator for home use installed.  

    Contact us if you need help choosing a backup generator for your UPS

    If you feel a little out of your depth and want to make sure that you avoid any unnecessary UPS / generator compatibility issues in the future, please do not hesitate to contact us. Not only can we help you determine the optimal combination of UPS system and back-up generator for your emergency power requirements, but we can also offer you our professional installation and maintenance services. 

    Isaac Prakash
    Isaac Prakash


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