2. Uninterrupted power supply
An Uninterrupted Power Supply , also
UninterruptiblePower source , UPS or battery/flywheel
backup , is an electrical apparatusthat provides emergency
power to a load when the input power source ,typically the
utility mains , fails
4. Offline UPS
❖ The mains to battery changeover time or battery to mains
changeover time in offline UPS low as compared to
inventor.
❖ Typically, changeover time in inverters is 500 millisecond
& OFFline UPS has changeover time of 3-8 milliseconds
6. Offline UPS
➢ In a time ,when mains AC is present ,Inverter provides the
output AC is the input mains.
➢ While, Offline UPS has built in Automatic VoltageRegulator
(AVR) TO regulate the output voltage close to 220V AC.
➢ Offline UPSs are normal weight UPSs and are widely used for
domestic computers .
7. Online UPS
❖ In this type of UPS, the system always remains on battery , whether
mains AC is present or not.
❖ When mains AC is present , it provides power to DC supply of
inventor section as well as charges the battery simultaneously.
❖ When mains AC is not present , it will run the connected load till the
battery has a recommended dischargeable level.
9. Advantages of UPS
✓ Protects from uncertain data loss
✓ Emergency power supply
✓ Protects the voltage sensitive devices from bad electricity
✓ Provides surge protection
✓ Maintains the battery life
✓ UPS gives a huge power back in the industries
10. Disadvantages of UPS
✓ Maintenance cost is quite high
✓ The startup cost is too much high
✓ Commercial uses requires a large number of batteries
11. Switch Mode Power Supply
▪ An electrical power supply that incorporates a switching regulator to
convert electrical power efficiently.
▪ It transfers power from a source , to a load , while converting voltage
and current characteristics .
▪ Voltage regulation is achieved by varying the ratio of on-to-off time .
13. 1. Input rectifier stage :
It is used to convert an AC input to DC . A SMPS with DC input does not
require this stage. The rectifier produces unregulated DC which is then
passed through the filter circuit.
2. Inverter stage :
The inverter stage converts DC whether directly from the input or from
the rectifier stage described above, to AC by running it through a power
oscillator.
14. 3.Output transformer:
If the output required is to be isolated from input , the inverted AC is used to
draw the primary windings of a high frequency transformer. This converts the
voltage up or down to the required output.
4 .Output rectifier:
If the DC output is required ,the AC output from the transformer is rectified.
5.Regulation:
Feedback circuit monitors the output voltage and compares it with the
reference voltage.
15. Applications of SMPS
❑ Machine tool industries
❑ Security systems (closed circuit cameras)
❑ Support supplies with PLC’s
❑ Personal computers
❑ Mobile phone chargers
16. Advantages of SMPS
• The efficiency is as high as 80 to 90%
• Less heat is generated so less power wastage
• The device is small in size and compact
• The manufacturing cost is reduced
• Provision for providing the required number of voltages
• Provide safety to other components
• The SMPS consists of simple and flexible technologies
17. Disadvantages of SMPS
• SMPS device is complex
• They produce electromagnetic interference
• They are damaged easily when power fluctuation arises
• They are expensive compared to LPS
• It is not easy to know the function of SMPS
