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UPS-Uninterruptible Power Supply

UPS:

 UPS is a device which provides power to the device and regulates it for the short duration in the absence of main electrical power. It consists of battery which stores the energy needed during the presence of power. It involves rectifier, batteries, power inverter and static switch of several components.

Rectifier:

Rectifier is used for converting AC into DC as usual. Here the rectifier is used fro two main functions:
  • Convert AC into DC to the supply  of filtered load or the supply inverter
  • Convert AC into DC to charge the battery
It is also used in charge controller purposes

Battery:

Battery  is used as a storage device. Rectifier converts AC from supply mains into DC. DC is stored in battery up to its charging capacity.It has two main functions:
  • It converts electrical energy into chemical energy and stores it in the presence of power through rectifier 
  • It converts chemical energy into electrical energy and delivers it to the load in the absence of power through inverter

Inverter:

Its main duty is to convert DC power present in battery into AC power. It usually consists of inverter bridge and filter circuits

Static Switches:

Static switch is nothing but the two SCR connected in reverse parallel combination. It is disconnected form all logic circuits. It is used as a two way switch for power conversion.


Types of UPS:

There are three distinct types of UPS:
  • Online UPS
  • Offline UPS
  • Electrical Generator

Online UPS:

Online ups
In online UPS the power will be delivered from UPS inverter continuously whether the main supply is on or off. The switching time is zero. Online UPS consists of two SCR T1 and T2. T1 will be always ON, but T2 will ON only during the bye pass condition. The battery will be charged always irrespective of presence or absence of power. once the power is off, the power from the battery will be supplied to the load until the battery get discharged. Once the battery get discharged the system will shut down. Once the power resumes the battery will start its charging.

Offline UPS:

Offline UPS

In offline UPS the inverter will be off when the main power is on. Once the main power is off the inverter will be on to deliver the power. The switching time is considered to be less than 5ms. It is used in Computer or other devices where the small duration of switching time is negligible.

Electronic Generator:

Electric Generator

Electronic Generator is similar to the offline UPS except the switching time. Electronic Generator is used for long time. It lasts for 1 to 4 hours. It is used for house hold appliances such as fans, coolers,  fridge, TVs etc

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