How UPS Systems work | What is UPS and how does it work? | Why Do You Need A UPS?

WhatsApp Group Join Now

Table of Contents

What is UPS and how does it work? | How does an Uninterruptible Power Supply (UPS) work?

Do you know what is UPS? Why is it used and how many types are there? If you are a computer user then you probably already know about UPS because it is used in most computers & industrial machines.

But even if there is no complete information, there is no need to panic because in today’s article we will try to provide information regarding what is UPS. During our daily work, we go through a state of power cuts many times. By the way, other electrical appliances like Fan, Lights, TV, Fridges, and Coolers are not affected much by this because they do not require a continuous power supply.

But if you have a computer system, then there is always a need for continuous power to use it properly, in such a situation, if the power is cut then there is also a risk of loss of our data. Just to overcome this problem, we need a device that can provide an interruption-free power supply for us. This type of device is called UPS.

This UPS or uninterruptible power supply (UPS) is a device that continuously supplies power to the devices connected to it. If I say it in simple language, then it is a surge bar to which a battery is attached.

Even if there is a power cut, the battery still supplies the power of that requirement until your main power is restored or the full charge of that battery is not used up. If you want to know more about UPS then you should read this post What is UPS completely further because I have tried to provide other related information along with UPS.

Hope you like this effort of mine, then without delay let’s start and get complete information about how UPS works and how many types it is.

What is UPS? | How UPS Systems work – Critical Power Supplies | how does an ups power supply work

A UPS is an electrical device that provides emergency power to a load when the input power source or mains power fails.

What is UPS and how does it work?
What is UPS and how does it work?

UPS always supplies continuous power to the load whether the main supply is OFF or ON. The main application of UPS is that it supplies power to us in the absence of the main power supply so that our device does not have any issues. The source of energy for UPS is batteries.

The backup time (which means how long the UPS can provide power to the load in the absence of the main power supply) of any UPS depends on the type and quantity of batteries used in it.

What is the full form of UPS?

The full form of UPS is Uninterrupted Power Supply. This means that we can use UPS as an alternative power source that can continuously provide an interruption-free power supply load to us.

What is the need for UPS? | Why Do You Need A UPS? | how does uninterruptible power supply work

As there was development in electronics and computer-based devices, the use of sensitive electronic equipment such as Personal Computers, Super Computers, Data Processors, Digital Controllers, etc. also increased.

Such devices require an interruption-free power supply because these devices use memory and processors to handle data. As we know that these devices are very sensitive to the corrupted power supply.

Also Read: Recommended distance between the sofa and your tv

For example, if you turn off a personal computer directly, by removing its power plug, without shutting it down, then by doing this you can do data loss and sometimes your computer’s operating system is also corrupt. could.

To solve these problems, UPS is used for Device and Data Safety on the domestic side and also on the industrial side.

Some Important Parts of UPS | The importance of having a UPS

If we talk about the important parts of UPS, then it mainly consists of the following parts, which we will know in detail later:-

  • Rectifier (Battery Charger)
  • Static ByPass or Switch or Contactor
  • Battery
  • Inverter

Rectifier (Battery Charger)

As we all know that the main function of a rectifier is to convert AC to DC. It is used to charge the battery and it fits into the inverter circuit. Its output depends on the load requirement.

There are two main functions of this rectifier. The first is that it is used to charge the batteries so that the batteries are always in proper float voltage.

Where some manufacturers charge batteries just trickle to keep them in proper float voltage. Whereas some manufacturers use a more sophisticated method (three steps) in which first the fast charge is up to 90%, then there is a slow charge of up to 100%, and finally a turn-off charger once these batteries are fully charged.

At the same time, the second function of this is that the rectifier is used to convert the incoming power from A/C to D/C.

Static Bypass

Almost all online UPS have an internal static bypass circuit which acts as the first line of defense whenever you ever experience a failure within the UPS system.

Whenever a system failure occurs, this static bypass automatically closes the circuit and diverts the incoming power to rectifiers, batteries, and inverters so that it can load the load directly into utility-grade power (unconditioned).

Admittedly, this is not a conditioned power, but it still helps your system to function properly if the internal components of the UPS fail.

Also Read: Top 10 Smart LED TV Brands in India 2022


The heart of any UPS system is this Battery. These Batteries are mainly used to store energy. Remember, if the main power fails in the future, then these batteries are used. Lead and acid are mainly used in these batteries. And there are always reactions going on in these acids.

These batteries also have age and after a few years, they also have to be replaced. Batteries have a lifespan of 4 to 6 years. Special care has to be taken of these batteries and Distilled water has to be filled in them from time to time, which helps in the ongoing reaction in it.


This inverter is the final and main part of the UPS system. It works just opposite to the process of the rectifier. Meaning that it converts the incoming DC supply into AC for the use of the load. It accepts D/C from D.C buses and further supplies it to the rectifier and battery.

If ever there is a power failure, then the rectifier and current cannot be provided to the D/C buss, so only batteries provide power to the entire system. These batteries continue to provide power to the D/C buss until they are depleted.

Once the batteries are depleted then the system reaches a state of jeopardy and keeps looking for an external power source. Where the power from outside is provided with the help of a generator.

The output of the inverter is a sinewave. This D.C. Converts to A.C of constant frequency and amplitude.

What are the problems with the Main Power Supply? | problems of Main Power Supply?

There are many types of interruptions in the main power supply in different forms. These fluctuations can harm our sensitive electronic equipment and data. Therefore the best solution is to use UPS. Let us know about some such corruption.

Voltage Fluctuations

In a mains power supply, the voltage often increases or decreases, as compared to the rated voltage. For example, the voltage fluctuates in our homes from 210 Volts to 240 Volts.

We can use a digital voltmeter to see these fluctuations. The more these fluctuations, the more damage they can do to our devices.

Transient Impulses

The original sine wave of the alternating supply can be easily disturbed due to any reason due to which fluctuations in amplitude can be seen. These disturbances are also called Transient Impulses.

The instant increase in amplitude is called a spike and the instant decrease is called a notch.

Voltage Surges

When we connect a heavy load to the power supply, then the voltage of the entire system may increase or decrease for some time. These variations are called Voltage Surges.


The distortion in Alternating Sine Waves which comes for a short time is called Noise. The main reason for their origin is Radi and TV transmission, or even poor grounding. Noise can damage data and equipment.

Frequency Variation

If there is an instantaneous change in the load, then it can cause a variation in the supply’s frequency, which can damage the data.


For any reason, if there is an instant failure in the mains power supply, then it is called blackout. This is not good for the equipment.


If there are planned power cuts due to overloading of power then it is called brownouts.

Types of UPS

Several types of designs are used to implement UPS systems, where all have distinct performance characteristics. The most common design approaches that are followed are.

  1. Standby
  2. Line Interactive
  3. Standby online hybrid
  4. Standby-Ferro
  5. Double Conversion On-Line
  6. Delta Conversion On-Line

The Standby UPS

This Standby is the most common type used in Personal Computers. The transfer switch in this UPS is set to select filtered AC input as the primary power source (solid line path), and it will switch the battery/inverter as a backup source if the primary source fails. Then.

If this happens then the transfer switch will have to operate and the load will have to be switched over the battery/inverter backup. This inverter will start only when the power fails, hence the name “Standby.

The Line Interactive UPS

This Line Interactive up is also a very common design that is used in small businesses, web, and departmental servers. By its design, the battery-to-AC power converter (inverter) has to be always connected to the output of the UPS.

When the AC power of the input is normal, then it is making the inverter operate in the reverse order so that it is getting charged.

When the input power fails, then the transfer switch opens and the UPS output starts flowing from the power battery. Here the inverter is always on and connected to the output, so this design provides additional filtering and produces fewer switching transients as compared to standby UPS. Apart from this, it also does voltage regulation properly.

Standby Online Hybrid

These Standby On-Line Hybrids are also known as “online” UPS. This type of UPS is used below 10kVA. In this also standby DC tDC converter battery is switched on when main AC power failure is detected, just like in standby UPS.

In this, the battery charger is also very small like in standby UPS. Due to the capacitors in the DC combiner, the UPS does not exhibit any transfer time during AC power failure. This design is also sometimes used with an additional transfer switch so that any malfunction or overload can bypass it.

Also Read: 10 Electrical Safety Tips For The Workplace

The Standby-FerrUPS

There was a time when Standby-FerrUPS was used the most in the range of 3-15kVA. Its design depends on a special saturating transformer which has three windings (power connections).

Its primary power path is starting from the AC input, from the transfer switch to the transformer, and finally to the output. When a power failure occurs, the transfer switch opens, and the inverter picks up the output load.

In these Standby-Ferr designs, the inverter is in standby mode, and it is energized when the input power fails and the transfer switch opens. This transformer has a special “Ferro-resonant” capability, which provides it with limited voltage regulation and “shaping” the output waveform.

The isolation that the Ferrtransformer provides due to AC power transients is better than any available filter. Even though it is a standby UPS by design, this Standby-Ferr generates a lot of heat as it is inefficient from the beginning. The design of these UPS is also very big and heavy compared to the rest.

The reason for not using these UPSs anymore is that they can be fundamentally unstable when they are working according to the power supply load of a modern computer.

All large servers and routers use “Power Factor Corrected” power supplies that provide a negative input resistance above certain frequency ranges; When coupled to a Ferrtransformer with a high and resonant impedance, it can cause spontaneous and damaging oscillations.

The Double Conversion On-Line UPS

This is a very common type of Uninterruptible power supply above 10kVA. It is similar to a standby UPS but has a primary power path inverter instead of an AC main.

In a Double Conversion On-Line design, the failure of the input AC does not activate the transfer switch, as the input AC is not the primary source here, but it is a backup source. But this online mode of operation shows transfer time only when the power that comes from the primary battery charger/battery/inverter power path fails.

This happens when any block fails in this power path. Here the inverter power also drops out for some time, causing a transfer, this transfer can happen even if sudden load changes or internal control problems arise in the inverter.

Double Conversion On-Line UPS systems also exhibit transfer time, but in different conditions which is quite different from standby and line-interactive UPS.

Where a Standby and Line Interactive UPS exhibits a transfer time when a blackout occurs, a double-conversion online UPS exhibits a transfer time when there is a large load step or inrush current.

Both the battery charger and inverter convert the entire load power that flows into the design, thereby reducing efficiency and increasing heat generation.

The Delta Conversion On-Line UPS

The design of Delta Conversion On-Line Uninterruptible power supply is a new technology specially introduced to overcome the drawback of Double Conversion On-Line design and it is available in the range of 5kVA to 1 MW.

Similar to the Double Conversion On-Line design, the Delta Conversion On-Line Uninterruptible power supply also always has an inverter that supplies the load voltage. But here additional Delta Converter contributes power to the inverter output.

But in such conditions as AC failure or disturbances, this design exhibits behavior like Double Conversion On-Line.

If I explain to you in an easy way, then in this UPS the most attention is given to energy efficiency. The main purpose of Delta Conversion technology is to save energy.

To do this, they carry energy only in the difference (delta) between starting and ending points. Double Conversion On-Line Uninterruptible power supply converts the power of the battery and then reverses it, while in Delta Converter moves the components of the power from input to output.

TypeBenefitsLimitationsOur’s Findings
StandbyLow-cost high-efficiency compactUses a battery during brownouts Impractical for over 2kVABest value for personal workstations
Line InteractiveHigh-reliability High-efficiency Good voltage conditioningImpractical over 5kVAThis very popular UPS type is in existence because of its high-reliability ideal for rack or distributed servers and harsh power environments
Standby On-Line HybridExcellent voltage conditioning Low-efficiency Low-reliability High costImpractical over 5kVALine Interactive offers better reliability and similar conditioning in a better value
Standby FerroExcellent voltage Conditioning High reliabilityLow efficiency unstable in combination with some loads and generatorsIt has a limited application as it has low-efficiency and instability issues and the N+ 1 On-Line design offers even better reliability.
Double Conversion On-LineExcellent voltage conditioning ease of parallelingLow efficiency Expensive under 5kVAWell suited for N+ 1 designs
Delta Conversion On-LineExcellent voltage conditioningHigh efficiency Impractical under 5kVAHigh efficiency, it significantly reduces life-cycle cost in large installations

Also Read: Importance of Electrical Installation and Equipment Meaning As Per Companies Act 2022

What is the difference between UPS and Inverter?

By the way, there is a lot of difference between an Uninterruptible power supply and an Inverter, so I have explained the difference between the two in detail below for your understanding.

Technically, what is the difference between these two

Uninterruptible power supply (UPS) where provides a continuous power supply when a power cut occurs. Whereas the inverter circuit only converts and supplies the DC current of the battery to AC.

Practically, what is the difference between these two

So let’s know how these two are practically different:-

1. UPS: Uninterruptible power supply (UPS) provides us with power when there is a power cut. It is mainly used as a backup in desktop computers.

2. Inverter: This is a power backup solution. Its total unit consists of three components, the charges (which provide electricity to your home), battery, and inverter circuit which converts DC battery current into electricity. It is mainly used to supply backup power to the whole house.

3. UPS is mainly used for the backup of the system. If you connect your desktop computer to it, then if there is any power loss then the backup power starts in just 1 microsecond.

4. Inverter is not suitable for computer backup as it has a delay in switching. Due to this, the computer may crash which there is a risk of data loss. Apart from this, there is also a danger to the motherboard and hard disk.

5. UPS can only provide backup for 10 to 20 minutes. Because its main intention is to provide short time backup so that it can save programs and data. Whereas the purpose of inverters is that they can provide power backup to the whole house.

6. Flat plate and a tubular battery is used in the inverter to store electricity. It requires continuous maintenance such as filling the distilled water at regular intervals.

where is usedProvides backup to Desktop ComputerProvides power to other instruments of the house such as TV Fans and lights.
How long does it take to switchNegligibleMicrosecond
Backup time10 to 20 minutes3 to 4 hours depending on the battery
MaintenanceMaintainanceHave to fill water from time to time
Price’s2000 to 600010000 to 40000

What are the benefits of UPS

Maintenance of Power – The first and foremost advantage of UPS is that it controls the power flowing in your computer.

Continuity of Operation – It is a special thing in this that it keeps working continuously which means that even after the power is cut, it keeps doing it continuously and provides power backup.

Surge Protection – This protects your computer from all kinds of damage caused by currency fluctuations. For this, it controls the electricity coming into the computer.

Line Interactive UPS – It flows a balanced (controlled) electricity to your computer and even after the current is gone, it gives you enough time to save your work. Due to this, there is no loss of data and devices.

Emergency Power Source – UPS works like a very good Power Source in times of emergency. When the main power is off, you can use the electricity of your house using UPS/inverter. That’s why UPS is a great emergency power source.

NData Loss  – Due to sudden computer shutdown, there are many chances of data loss of the computer. With the presence of UPS, the fear that if the power goes out, the data will be lost. After the UPS light goes off, it easily supplies power for some time so that you can easily save your data and shut down the computer.

What are the disadvantages of UPS

Start-Up Cost – If you want to use Standby Uninterruptible power supply then it is very expensive for you. This means that the installation cost of UPS is a bit high initially.

Infrastructure – UPS is used according to the infrastructure. Therefore, the bigger the infrastructure, the bigger and more battery is used.

Maintenance Cost – The battery of UPS does not work for a long time and after some time it gets damaged, after which you have to replace its old battery completely and use a new battery. Along with this, this battery also needs maintenance from time to time.


As we have known that there are many types of UPS and they also have different applications. Therefore there is no such type of single UPS which is ideal for all applications.

Therefore it is very important to know about the different types of Uninterruptible power supply and their applications. Only then can we choose the right Uninterruptible power supply for ourselves. Compared to the disadvantages of UPS, its benefits are very high, which makes it special. According to the alternative source of power, UPS is a very good option.

I have full hope that I have told you guys what is UPS. Gave complete information about it and I hope you people have understood what is Uninterruptible power supply is.

I request all of you readers that you also share this information with your neighbors, relatives, your friends so that there will be awareness among us and everyone will benefit a lot from it. I need your cooperation so that I can pass on more new information to you guys.

It has always been my endeavor that I should always help my readers or readers from all sides, if you people have any doubt of any kind, then you can ask me without any hesitation. I will definitely try to solve those doubts.

Do you like the article What is UPS and how does it work? How did you feel, do tell us by writing a comment so that we too get a chance to learn something from your thoughts and improve something? To show your happiness and curiosity towards my post, please share this post on social networks like Facebook, Twitter, etc.

Also, Read the Article: – 

Leave a Comment

WhatsApp Group Join Now