Choosing your UPS: Our great practical guide

  • FrançaisFrançais
  • EnglishEnglish

  • Choosing an UPS is not just a matter of looking at the price or its maximum power. We explain what you need to know before making any purchase.


    Choosing an UPS is not just a matter of looking at the price or its maximum power. We explain what you need to know before making any purchase.

    A UPS is never something you think about until you have a sudden power outage that takes away all your data. The purchase of a PC must always be accompanied by an UPS to avoid all the unpleasant surprises associated with the electricity fairy.

    What is an UPS?

    In its simplest form, an UPS is a battery. Its role is to continue to supply power to your PC when there is a power failure, but it is also used to regulate the voltage when it is not unstable. But today, a UPS does much more than that. It can regulate voltage, help maintain stable power. It also offers great autonomy and intelligent management via software on its PC.

    The different types of UPSs

    It’s not enough to buy a UPS to have peace of mind. There are three types which are Standby, Line-Interactive and Online and the choice depends on the problems you have with your current. Frequent black-out? Surges or brownouts throughout the day? You need to power a PC, but also a printer or a scanner?

    As with everything, your needs are key to choosing the right UPS, because the prices can really hit the ceiling.

    The Standby or Offline UPS

    Called Standby or Offline UPS, it is the simplest and cheapest of the models. Basically, it’s a battery. When the UPS detects a power outage, it triggers the battery and that’s it. There are light protections on the surge, but nothing more. Honestly, we don’t advise you to take it. Because the vagaries of the electricity fairy are more than a blackout.

    This is sufficient for small PCs or installations that are not sensitive. But we come back to the problem of needs. For example, I live in a town where voltage instability is the norm and not the exception. So not only do I need good battery life in the event of a blackout, but the voltage must be also stable. Buying a Standby / Offline UPS because it is the cheapest, will not solve my problem. Ultimately, I could switch to the Line-Interactive UPS.

    In fact, manufacturers tend to abandon it because of its lack of performance. However, it can be found around 100 to 125 dollars.

    Line-Interactive UPS

    The Line-Interactive UPS is currently the most common on the market. The range can go from 200 to 350 dollars. This is one of the reasons why manufacturers have ditched the Offline UPS, as the price difference narrows over the years due to the falling prices of technology components.

    The Line-Interactive UPS is from the above range, but it can be considered the opposite of the Standby UPS. The latter focuses on the battery while the Line-Interactive model focuses on fluctuations. Indeed, the first type UPS has few margins before switching to the UPS.

    On the other hand, the Line-Interactive UPS is designed to withstand different voltage ranges to manage voltage drops and peaks before switching to battery which increases battery life. With the line-interactive UPS, the UPS is part of the output and it is always on.

    The UPS can work in reverse (inverter) to charge the battery when the current is normal and switch to battery power when the input fails, which provides filtering and voltage regulation. Line-interactive UPS rely on the battery to condition power, so this type tends to discharge its battery more frequently than online UPS which condition power through the double conversion process.

    In the event of a power failure, the unit’s transfer switch opens and current flows from the battery to the UPS output. With the UPS still on and connected to the output, the line-interactive UPS provides additional filtering and generates reduced switching transients compared to a standby UPS. Line-interactive UPS systems are typically used in rack mount applications below 5,000 VA.

    Online or double conversion UPS

    It is the top-of-the-range UPS, intended for critical installations, which cannot withstand the slightest drop in voltage. It is called the double conversion UPS.

    Double conversion UPS involves the current being converted to direct current (DC) and then this DC current is converted back to alternating current (AC) again. This AC-DC / DC-AC design ensures an increased degree of load isolation from irregularities in the main power supply.

    The Online UPS takes current, converts it to DC using a rectifier to supply the battery and the load connected through the UPS, so that no power transfer switch is needed. If the power fails, the rectifier switches off the circuit and the batteries maintain current to the device connected to the UPS. When power returns, the rectifier resumes carrying most of the load and begins charging the batteries.

    Since current flows continuously through an Online UPS, the output is a perfect sine wave. This type of UPS protects the critical load from virtually all power disturbances, including subtle harmonics and waveform distortion.

    Basically it means that when you connect your PC or other device to a double conversion UPS, the PC is always running on the UPS. He doesn’t give a damn about what goes on the current. The UPS is responsible for managing a perfectly stable current so that nothing disturbs your device.

    Honestly, it’s one of my dreams to be able to buy one. But the price of a real Online UPS is 700 or 800 dollars for the cheapest models. We have unscrupulous manufacturers who offer double conversion UPSs for 250 or 300 dollars. It’s impossible to have this technology for this price.

    What are the possible problems with electricity?

    Blackouts, surges, or brownouts aren’t the only problems with your electricity. There are many others that may occur depending on the type of your facility and your region.

    • Spike Voltage – A brief, but intense, current spike usually caused by lightning. Voltage peaks can damage and destroy electronics, but also printed circuits and components.
    • Blackout – A power outage that lasts from a few seconds to several days. These are most often caused by extreme weather conditions, power shortages, accidents and power outages.
    • Voltage drop – An intentional or unintentional drop in voltage over an extended period of time. Under emergency conditions, power companies can lower the voltage of your electricity to reduce strained resources and prevent blackout.
    • Undervoltage – A undervoltage is also a type of voltage drop, but unlike the latter, it is sudden and brief.
    • Surge – Occurs when the incoming voltage is higher than normal and lasts longer than a voltage spike, but not high enough to be classified as a spike.
    • Frequency Noise – Also known as line noise, frequency noise can disrupt or degrade the performance of a circuit by injecting anomalies into the system.
    • Frequency Variation – This is not a common problem when the power supplies are stable, but it can occur when using generators and the power frequency fluctuates more than desired.
    • Harmonic Distortion – A deviation from the ideal electrical signal on a given power source.

    The UPS you need according to the electricity problems you are having

    The table below describes the UPS you need according to the electricity problems you are having by those listed above.

    Electricity problem Standby Line-Interactive Double Conversion
    Harmonic distortion X X
    Frequency variation X X
    Frequency noise X X
    Surge X
    Undervoltage X
    Voltage drop
    Blackout
    Voltage peak

    The size or autonomy of the UPS

    This is often the first criterion that people will look at when they want to choose a UPS. But this can appear misleading. Even if the stupid rule that a large UPS will have a large autonomy is true … Except that the price difference between a 650 VA UPS and another at 1300 VA is doubled.

    To have some headroom, you could try to take the 1300VA model, but it’s a waste of money if your PC is only asking for 500VA. You could use the extra money (and if you have too much, I’m still an taker) to buy extra batteries for your UPS. But between Watts, Voltage, VA, how to understand the real autonomy of an UPS.

    Understand the VA measurement of an UPS

    The VA measurement of an UPS means Voltampere and this relates to energy. We apply the formula Volt x Ampere to obtain it. So a 220-volt device operating at 10 amps gives you 2,200 VA. The difference between Watt and VA is:

    • VA indicates the energy supplied
    • Watt indicates the energy consumed

    As a general rule of thumb, you should always buy an UPS whose VA power is greater than the wattage consumed. It may sound very stupid, but many people mistakenly think that one VA = one Watt and that a 1500 VA UPS will support 1500 watts. Absolutely not.

    In fact, you can have models at 850, 750, or 600 Watts, but they are all sold as 1500 VA. It is linked to the power factor which is a technical parameter in the management of UPS and we do not want to dive into it. So when choosing your model, VA power is important, but also look at the maximum amount of Watts it supports.

    Always look at the power in Watts and don’t get caught up in the big VAs. For the power in Watts, you have the capacity and the load. Basically, the capacity shows the total power of your UPS in watts and the load is the sum in watts of all the devices that connect to it.

    Below, some common devices and their consumption in watts:

    • The central unit – 120 Watts
    • The monitor – 60 watts
    • External drive – 20 watts
    • Wireless router – 10 watts

    So if you have a PC with a monitor and 2 internal hard drives and a wireless router, then your consumption is 230 watts. Some may say that their PC power supply is 750 watts on its own and therefore, they need a lot more. No, the PC power supply provides 750 watts, but it does not consume all of those 750 watts.

    Tests were carried out on high-end processors with very greedy graphics cards and we arrived around 350 to 400 watts and we are talking about a real racehorse here. So what you are doing is adding up the wattage consumption of all of your components like CPU, RAM, PC power, graphics card, hard drives, fans, etc. And you will have a good idea of ​​your actual consumption and don’t forget to add your monitors.

    UPS autonomy

    Not all of these energy measurements will tell you exactly how long your UPS is. But an average in the market is 20 to 30 minutes. It is a simple question of consumption. If you took a large 3000 VA UPS and it only supplies your PC, in the event of a power cut, you will have a lot of autonomy. A 650 to 1000 VA UPS can give you those 20 to 30 minutes for a standard PC with a monitor.

    The UPS with a pure or simulated sine wave signal

    Another parameter that must be taken into account when purchasing an UPS is its sinusoidal signal type. We will try to stay as clear as possible. You have an UPS that’s plugged in, the power is working and it’s pretty stable. And so, the UPS will produce a pure sine wave signal since it does not need to intervene to correct the signal.

    On the other hand, if you have surges, brownouts, etc., then the UPS will take over and produce a simulated sinusoidal signal. We can see the difference between the two below:

    Choosing an UPS is not just a matter of looking at the price or its maximum power. We explain what you need to know before making any purchase.

    A pure sine wave

    Choosing an UPS is not just a matter of looking at the price or its maximum power. We explain what you need to know before making any purchase.

    A simulated sinusoidal signal

    In a pure signal, the current is very stable. In the simulated version, you will have little jerks and sometimes you will hear it if the UPS clicks. This is a sign that the UPS is facing electrical instability and is trying to correct it. The click of an UPS can also indicate batteries at the end of their life and need to be replaced.

    If you have iMacs or devices with Energy Standard 80 Plus via Active PFC or Energy Star, then you need an UPS that produces a pure sine wave signal. The Active PFC for Power Factor Correction which are controllers that will distribute energy in the most efficient way possible.

    The only way to find out is to ask the manufacturer, because this characteristic is not often present in the sheet. In general, Active PFC is mostly found in high-end UPSs.

    The price of an UPS

    Given the many criteria that must be considered when choosing a UPS, then it is obvious that we cannot give you a precise idea. First, look at the problems with your electricity. Voltage peak, drop, blackout, etc. Next, calculate the total wattage of your devices and try to find an equivalence in VA for your UPS. It is better if the manufacturer clearly indicates the wattage.

    After testing dozens of models, we estimate that the minimum price is 200 dollars to find a model that will last for several years. In general, you will get a Line-Interactive model at this price which is more than sufficient for most general public needs.

    Then, if you have a better budget, then you could go for the high end skies with the double conversion UPS which will give you the best autonomy and electrical stability. That is, even if you are on a boat in the middle of a thunderstorm and you are using lightning electricity to run your PC, then this UPS will hold up.

    The best UPS brands

    The world of UPS is small and we quickly know the best brands. APC, Cyberpower or Eaton are the leaders in UPS. Their models are not given, but we benefit from their expertise of several decades in this field.

    You also have small brands that are launching, especially in China. But the UPS is too valuable an accessory to use models out of nowhere. An UPS that mismanages electricity and its instability can burn your PC and everything that goes with it!

    In conclusion

    Choosing an UPS isn’t just about looking at maximum power and picking the cheapest model. There are a lot of criteria to look at such as the electrical problems you face most often, the devices you want to protect, the range you are looking for in the event of an outage and your budget.

    Try to find the wattage of your components and take 20-30% more headroom from your UPS. Avoid the Offline models which are no longer suitable today and go directly to the Line-interactive UPSs which offer the best quality / price ratio.

    L'équipe de Comparaland

    Copywriter since 2009 and webmaster since 2011.

    I am interested in all subjects such as politics, culture, geopolitics, economy or technology. Any information to enlighten my mind and therefore yours in a dark and adrift world. I am the author of several books

    To contact me personally:

    Leave a Reply

    Your email address will not be published. Required fields are marked *