What is a UPS? (Uninterruptible Power Supply)

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An Uninterruptible Power Supply is a device that is used to keep computers and equipment safe when there is a loss, or a significant reduction, in the primary power source.

Once this is detected, the control is transfer over to the batteries, and via an inverter, the batteries DC voltage is converted into AC for the devices.

In reality, it doesn’t have to be computers systems and equipment that are kept alive by UPS. It could be anything from a fish tank, to a foot massager!

We aren’t just talking about plain power outages, lights off, TV off, everything, but we can sometimes get spikes in power where a sudden drop can assure our devices are momentarily powered off, or something known as a brown-out.

The amount of time the UPS can sustain a system for can vary, but it allows the opportunity for the issue to be resolved, or at the very least, allows for the systems to be shut down in a controlled manner.

Since a UPS is a system that uses batteries to power a system should the supply be compromised, we, of course, have batteries and a battery charger.

Since the batteries use DC current and our incoming supply is AC current, we need to convert DC to AC using an inverter.

A UPS provides second-level surge protection, but although it does provide some protection, it should usually be used alongside an adequate Surge Protection Device (SPD) to extend the life of the UPS as well as the attached equipment.

Firstly, and the most common in smaller systems is the Standby or Offline UPS.

The Standby UPS lays in wait for its time to spring into action, and once there is a power failure, it takes control. The Standby UPS tends to be the most cost-effective UPS available.

Next up, we have the Line Interactive UPS. It is very similar to a Standby UPS but with the added ability to regulate voltage automatically.

This means that it monitors the incoming supply and can help out if it detects that the voltage is a bit low, or a spike is causing it to go too high.

It can add or subtract power in this way to make the output to our devices constant!

This type of UPS is particularly useful for the brown-out situation we’ve already mentioned, or power spikes or surges.

Now we have the Online Double Conversion UPS. This type of UPS is efficient as the primary source of power isn’t the incoming supply, rather it is the battery power.

So when we have a power outage, there is no transfer switch to close, meaning no time to switch that you can get with the other type of UPSs.

When the incoming supply is ON, the batteries simply charge up. It is called a double-conversion because it converts the AC incoming supply to DC, and then the inverter converts it back to AC for the output.

In general, it ensures a far higher degree of isolation of the load from the irregularities on the mains supply.

These are the most common types of UPS available. Of course, there are other types that fit a particular form or function, but these tend to be for more specialist needs.


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  1. Mark Allen on December 2, 2020 at 9:35 pm

    Wow, I bet those UPSs drain out pretty good when the wind ain’t blowing. Even with the wind blowing you’d only have a very small percentage of what you really need to make things work. Due to this, I doubt the accuracy of your entire video. I’ll stick with my APCs and Salem nuclear plant, thank you.

  2. rhythmandacoustics on December 2, 2020 at 9:35 pm

    3:48 why separate the battery charger and the rectifier? Battery chargers already have rectifiers in them.

  3. Rob erto on December 2, 2020 at 9:36 pm

    Hello: thanks a lot for your video. Could you please inform if this video is for commercial UPS’s and not for Industrial UPS’s? Regards.

  4. Amira Janah on December 2, 2020 at 9:36 pm

    Thank you for the video , the explanation was so brilliant, now how can i size the UPS power of a system ?

  5. ahmed adardor on December 2, 2020 at 9:37 pm

    Thanks all realpars team

  6. Zdan Germany Zydan on December 2, 2020 at 9:39 pm

    Excuse me,what is defference between UPS online and offline?

  7. Frs Kwn on December 2, 2020 at 9:39 pm

    What if I plug in something that requires more wattage into my UPS’ "battery and surge protection" sockets for the sake of not having "Surge only" sockets . Would it damage my equipment?

  8. RealZanzi on December 2, 2020 at 9:39 pm


  9. coltz89 on December 2, 2020 at 9:39 pm

    Do your courses cover FBD and STL as well? I notice a lot of the icons are ladder which isn’t used in my company. Thanks!

  10. samhoodnificent on December 2, 2020 at 9:41 pm

    Is it possible to run the UPS on a solar system for off the grid power for a house

  11. إيليا on December 2, 2020 at 9:41 pm

    Brilliant crew 👌

  12. Ardent Dfender on December 2, 2020 at 9:43 pm

    RealPars always exceed my expectations on each and every topic, and that’s the way it should always be. Promise of another video, and overdeliver in its content, knowledge and ease of understanding.

  13. ramin alikhani on December 2, 2020 at 9:43 pm

    Excellent! I barely could finish high school but I could understand everything in this video, because the explanation was brilliant! Now I can send my resume as an electronic engineer!

  14. safa haidar on December 2, 2020 at 9:47 pm

    is the battery charger coming with rectifier in online and offline ups just like the double conversion ups?is there any battery charger in double conversion ups? please clarify it for me

  15. Arumuga Raja Palraj on December 2, 2020 at 9:51 pm

    Nice video 👌 ( UPS )
    Please upload how to transfer the load to battery bank ( Setting ) & troubleshooting

  16. Ibrahim Daruwala on December 2, 2020 at 9:52 pm


  17. Sol Man on December 2, 2020 at 9:52 pm

    Thank you. Easy to understan

  18. Xenia Kekae on December 2, 2020 at 9:55 pm

    I’m a business student working with a Tech Company now and this video was perfectly explained. GREAT JOB!

  19. BR Electricity KH [បូរី] on December 2, 2020 at 9:55 pm

    Thank you very much bro for sharing video ups good.

  20. Liou Jason on December 2, 2020 at 9:55 pm

    This video is very helpful.
    deeply thankful.

  21. Alikhan Zulkashov on December 2, 2020 at 9:56 pm

    I would like to ask if the battery charger works as the same as the rectifier does converting AC to DC?

  22. Furaido Chikin on December 2, 2020 at 10:02 pm

    I will buy ups now

    Thanks for the info

  23. Sheraz Saeed on December 2, 2020 at 10:03 pm

    you r one of the best technical youtuber by far distance😍

  24. Waseem Haider on December 2, 2020 at 10:06 pm

    Can you please explain Static switch in UPS. Its construction,its components and its working.

  25. Alex አመክንዮ on December 2, 2020 at 10:08 pm

    Can i use an ips ( Instant power supply) instead of an ups?

  26. Loyiso Vamsinya on December 2, 2020 at 10:08 pm

    Good work keep it up wish u guyz can create more stronger ups the one can manage heavy load for example fridge that will be better

  27. Omen Dragon on December 2, 2020 at 10:09 pm

    Just found out this existed. Good to know.

  28. Celso Madeira on December 2, 2020 at 10:10 pm

    Excelente! Good job! Real pars each time better

  29. khushi jain on December 2, 2020 at 10:10 pm

    Thankful to you that we can learn!

  30. ramin alikhani on December 2, 2020 at 10:12 pm

    Much better than wikipedia!

  31. Gangsta A Glide on December 2, 2020 at 10:13 pm

    Thaaank youu sir

  32. Chris Brand on December 2, 2020 at 10:16 pm

    Thank you very much

  33. Engineer SAM on December 2, 2020 at 10:17 pm

    Can we know which type of UPS are we dealing with by looking at its brochure?

  34. Hassan Faheem on December 2, 2020 at 10:19 pm

    Please Do make a video on wapda inverter and conveter

  35. Anirban Jana on December 2, 2020 at 10:19 pm

    When the electricity is available, does the UPS charge automatically?? Or should we need to switch off the UPS and charge it???

  36. hussain6953 on December 2, 2020 at 10:19 pm

    Great Job.

  37. suriya prakash on December 2, 2020 at 10:21 pm

    Can you put a video on Gas flow meters like RPD meter, Turbine meter, Ultrasonic meter and its uses and selection based on application.

  38. kapil6996 on December 2, 2020 at 10:23 pm

    Nice video Sir. Please make video on SPD, Barriers and Isolators. Difference between barrier and isolator

  39. Kenny W on December 2, 2020 at 10:23 pm

    Great channel and great content.

  40. ARPIT Mishra on December 2, 2020 at 10:25 pm

    very good explanation

  41. Derin A. Maleek on December 2, 2020 at 10:26 pm

    hello ….please make a video about (SPPA T 3000) CONTROL system best regards

  42. Fred Dukes on December 2, 2020 at 10:26 pm

    Confused on how much wattage of the UPS I should buy, I have a high end gaming rig and here are my specs.

    CPU: ryzen 5 3600
    RAM: T-force delta 2×8 16gb ddr4 3000mhz
    GPU: RTX 2060 SUPER 8gb

    Do I need a UPS with a wattage higher than my PSU? Any advice would be appreciated!

  43. Nikki Holbert on December 2, 2020 at 10:26 pm

    So..if I’m building a pc..Do you buy this instead of a power supply or do you get both?

  44. huynh tuanphuong on December 2, 2020 at 10:29 pm


  45. rose e on December 2, 2020 at 10:30 pm

    thank you for this :))

  46. Jiwan Verma on December 2, 2020 at 10:30 pm

    Pls inform do we need to keep ups switch on from switch board( switch off from powwer button) all the time even when we are not working on computer. Keeping switch on all the time affects internal part as ups get little hot. UPS ( APC BACK 600 IN).

  47. Eliel Murmu on December 2, 2020 at 10:31 pm

    Very helpful!

  48. Wail Rimouche on December 2, 2020 at 10:31 pm

    Can we get a variable frequency drive that is also a UPS?

  49. Sudeep Biswas on December 2, 2020 at 10:34 pm

    Nice sir !!!

  50. Riyadh H on December 2, 2020 at 10:34 pm

    Great explanation! 👍

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