UPS- Uninterrupted Power Supply
Types, Working principle, Parts and block diagram.


  1. What is the UPS power supply?
  2. Schematic diagram.
  3. Construction or parts of UPS.
  4. Types of UPS.

1 - What is the UPS power supply?:

UPS is an uninterrupted power supply and it is called other name as backup supply. When EB supply is switched off then UPS is switched on quickly without any interruption as form of backup supply. When power supply is resumed again then UPS supply is switched off quickly without any interruption. It works in auto mode.

Uninterrupted power supply(UPS): parts, types their functions

It means the running equipment on load will not be effective during power supply Off condition because same time the back up power supply is provided by UPS without any interruption. So in this way the running equipment will not be trip and will work on continue.

2 - UPS single line diagram :

Uninterrupted power supply(UPS): types and block diagram

3 - Parts of UPS :

UPS is a electrical equipment which is the group of electrical devices just like as Rectifier, battery, invertor and static switch. The parts detail below mentioned

1- Rectifier/ battery charger:

Rectifier is an electrical convertor as AC to DC with assistant of diode. Rectifier is used in on line UPS and it also works as battery charger.

2- Battery bank:

Battery is a DC supply storage device which is used for providing DC supply to the inverter. One battery DC supply is 12 volt. A nos of batteries are used as battery bank for improving power backup. Mostly two battery banks are connected in UPS.

3- Invertor:

Invertor is a convertor which converts DC supply into AC supply. Its works as apposite in comparison of diode. SCR- silicon conductor rectifier are used in inverter. It is the main part of UPS because during power supply switched OFF, It provides the backup supply.

4- Static Switch:

Static switch is the auto switching device which is used for quick supply changing without interruption. Really it is the brain mind of UPS. It works many mode according condition like as UPS mode, bypass mode. If the UPS is running on supply mode then suddenly inverter is showing alarm so due to this situation, the supply will be changed into bypass mode.

5- UPS LCD display:

LCD display is a digital monitoring device which is used for controlling and monitoring of UPS. All parameters can be checked easily. A block diagram is shown on display about UPS running status, any alarm and breaker condition.

4 - Types of UPS :

Different type UPS are used like as single phase UPS, three phase ups etc.

  • Standby or Off line UPS:
  • On line UPS:
1- Standby or Off line UPS:

Standby UPS is an electrical supply source which works during power supply fails then it provides quick supply within 1.5 to 4.0 millisecond. When the UPS is running on EB supply mode then the inverter will be on Off mode. The time of power supply fails, the inverter starts quick and provides supply to the load. It means the inverter starts after supply switch off.

It is a low cost and effective. It is used upto 1.5 KVA load capacity as computers, small business, small web services .

2- On line UPS:

On line UPS is an electrical backup supply which works during power supply fails. Power supply does not connect directly to the load. It is connected through rectifier and inverter. It is used mostly above 5 KVA to 1.6 MW capacity.

1- Double conversion on line UPS:

According construction of double conversion, the power supply is converted as AC to DC and DC to AC or as per diagram. The power supply is connected to the rectifier and rectifier is connected to the inverter and battery after that the inverter is connected to static switch and battery is connected to the inverter. In the end the static switch is connected to the load and bypass supply. If any alarm is available in rectifier or inverter side then power supply is connected with bypass supply source by static switch.

2- Delta conversion on line UPS:

Delta type on line UPS is an electrical backup supply equipment which works as double conversion type UPS but a additional feature is added in input supply like as delta transformer. As per construction or diagram, The delta transformer is connected to the input power supply source before rectifier. Delta transformer input is connect with input supply source and output is connected to rectifier input terminal othe construction as same double conversion on line UPS.

Delta transformer has two important features as one is reduces energy losses due to harmonic, heating and second is to control the input current regulating during battery charging mode.

3- Single phase UPS:

Single phase UPS is mostly used in domestic, residential, commercial, societies etc. Basically it is also used for backup and emergency light. Single phase supply 240 volt is used. It is available upto 5 KVA. Single phase equipment are operated like as computer, lights, refrigerator etc.

4- Three phase UPS:

Three phase UPS is mostly used in industries, residential societies and commercial etc. Basically it is also used for backup and emergency light. Three phase supply 415 volt is used. It is available above 5 KVA. Single phase equipment are operated like as computer, lights, production machines etc.

Go back to index ↑

Electrical and Mechanical Job Interview Training.
Get boost in your job or get new opportunity

Technical e book is used for storing data in soft formate which may be pdf, ms word or others as availability.

Electrical E-book

(Get important knowledge about industrial electrical, building maintenance in E-book )

HT system, LT system, Transformer, Electrical panel, Motor and Starter, Circuit breakers, Protection relays, Measuring meters.

Interview is a physical verbal communication activity which is performed between job seekers and employers so that skilled person could be selected.

Technical Interview

( Electrical system, Diesel generator, BMS, AC, Chiller plant,
UPS, WTP, STP, ETP, Fire and safety.)

electrician, maintenance supervisor, AC operator, chiller plant operator, DG operator, BMS operator, Shift engineer, Maintenance engineer, technical executive, sr. engineer, assistant facility manager,


Learn Fast and Improve Your Skill in Electrical Field Basic and practical theory, repair and maintenance, protection and testing.

For any query :- write to us as below mentioned email ..

For official :-

For technical information :-

For interview preparation :-
Subscribe for Get Latest Post Updates in Your Email Inbox
Join Free Email Service